We say inviscid dissipation occurs when a vanishing viscosity limit does not satisfy energy balance. A closely related phenomenon is an omalous dissipation\, where\, in the limit of vanishing viscosity\, the to tal dissipation does not vanish. In this talk we will discuss recent resul ts on avoiding these phenomena in 2D incompressible flows\, with and witho ut forcing.

DTEND;TZID=Europe/Zurich:20240712T160000 END:VEVENT BEGIN:VEVENT UID:news1695@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240702T162928 DTSTART;TZID=Europe/Zurich:20240712T141500 SUMMARY:An afternoon of analysis talks: Alexander Kiselev (Duke University) DESCRIPTION:There exist many regularization mechanisms in nonlinear PDE tha t help make solutions more regular or prevent formation of singularity: di ffusion\, dispersion\, damping. A relatively less understood regularizatio n mechanism is transport. There is evidence that in the fundamental PDE of fluid mechanics such as Euler or Navier-Stokes\, transport can play a reg ularizing role. In this talk\, I will discuss another instance where this phenomenon appears: the Patlak-Keler-Segel equation of chemotaxis. Chemota ctic blow up in the context of the Patlak-Keller-Segel equation is an exte nsively studied phenomenon. In recent years\, it has been shown that the p resence of a given fluid advection can arrest singularity formation given that the fluid flow possesses mixing or diffusion enhancing properties and its amplitude is sufficiently strong. This talk will focus on the case wh en the fluid advection is active: the Patlak-Keller-Segel equation coupled with fluid that obeys Darcy's law for incompressible porous media flow vi a gravity. Surprisingly\, in this context\, in contrast with the passive a dvection\, active fluid is capable of suppressing chemotactic blow up at a rbitrary small coupling strength: namely\, the system always has globally regular solutions. The talk is based on work joint with Zhongtian Hu and Y ao Yao. X-ALT-DESC:There exist many regularization mechanisms in nonlinear PDE t
hat help make solutions more regular or prevent formation of singularity:
diffusion\, dispersion\, damping. A relatively less understood regularizat
ion mechanism is transport. There is evidence that in the fundamental PDE
of fluid mechanics such as Euler or Navier-Stokes\, transport can play a r
egularizing role. In this talk\, I will discuss another instance where thi
s phenomenon appears: the Patlak-Keler-Segel equation of chemotaxis. Chemo
tactic blow up in the context of the Patlak-Keller-Segel equation is an ex
tensively studied phenomenon. In recent years\, it has been shown that the
presence of a given fluid advection can arrest singularity formation give
n that the fluid flow possesses mixing or diffusion enhancing properties a
nd its amplitude is sufficiently strong. This talk will focus on the case
when the fluid advection is active: the Patlak-Keller-Segel equation coupl
ed with fluid that obeys Darcy's law for incompressible porous media flow
via gravity. Surprisingly\, in this context\, in contrast with the passive
advection\, active fluid is capable of suppressing chemotactic blow up at
arbitrary small coupling strength: namely\, the system always has globall
y regular solutions. The talk is based on work joint with Zhongtian Hu and
Yao Yao.

\;

Federated learning has emerged as an important paradigm in mo dern large-scale machine learning. Unlike traditional centralized learning \, where models are trained using large datasets stored on a central serve r\, federated learning keeps the training data distributed across many cli ents\, such as phones\, network sensors\, hospitals\, or other local infor mation sources. In this setting\, communication-efficient optimization alg orithms are crucial. We provide a brief introduction to local update metho ds developed for federated optimization and discuss their worst-case compl exity. Surprisingly\, these methods often perform much better in practice than predicted by theoretical analyses using classical assumptions. Recent years have revealed that their performance can be better described using refined notions that capture the similarity among client objectives. In th is talk\, we introduce a generic framework based on a distributed proximal point algorithm\, which consolidates many of our insights and allows for the adaptation of arbitrary centralized optimization algorithms to the con vex federated setting (even with acceleration). Our theoretical analysis s hows that the derived methods enjoy faster convergence if the degree of si milarity among clients is high. Based on joint work with Xiaowen Jiang and Anton Rodomanov.

\n\n END:VEVENT BEGIN:VEVENT UID:news1697@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240528T110624 DTSTART;TZID=Europe/Zurich:20240605T190000 SUMMARY: _Prompt_Battle DESCRIPTION:Using the power of the keyboards\, you generate challenging\, b eautiful or funny images and illustrations on the topic of Europe using te xt\, or prompts for short\, which are presented to our audience for voting . But be careful - if you prompt against the AI's moral codes\, your pictu res will not be generated and only your prompts will remain visible. We pl ay according to the knockout principle in several rounds.\\r\\nAnd here's a little announcement: We already know that National Councillor Sibel Arsl an and Franziska Stier\, BastA! management\, will be competing with you in the prompting game! We are very happy about this and are in the process o f expanding the circle of other exciting\, locally committed players.\\r\\ nFamous or not\, in the end it's the applause of the audience that counts. In addition to fame and recognition\, the winners will receive our beauti ful Europa bag with lots of exciting and drinkable surprises!\\r\\nHow to register?\\r\\nGet your ticket here! [https://www.operation-libero.ch/de/s hop/tickets-fuers-promptbattle]\\r\\n Participation ticket: You want to j oin in? Get a participation ticket. Audience ticket: If you want to be th ere and vote\, the audience ticket is just right for you! \\r\\nWhat does the schedule look like?\\r\\n From 7 pm: Warm-up with the developers of t he "Prompt-o-Lympics" 8 pm: Start Until 10 pm: Aperitif X-ALT-DESC:Using the power of the keyboards\, you generate challenging\, beautiful or funny images and illustrations on the topic of Europe using text\, or prompts for short\, which are presented to our audience for voti ng. But be careful - if you prompt against the AI's moral codes\, your pic tures will not be generated and only your prompts will remain visible. We play according to the knockout principle in several rounds.

\nAnd he
re's a little announcement: We already know that National Councillor **Franziska Stier**\, BastA! man
agement\, will be competing with you in the prompting game! We are very ha
ppy about this and are in the process of expanding the circle of other exc
iting\, locally committed players.

**Famous or not\, in the
end it's the applause of the audience that counts**. In addition to
fame and recognition\, the winners will receive our beautiful Europa bag
with lots of exciting and drinkable surprises!

**How to regi
ster?**

**Participation ticket:**You want to join in? Get a participation ticket.**Audience ticket:**If you want to be there and vote\, the audience ticket is just right for you!

**What does the schedule look like?**

**From 7 pm:**Warm-up with the developers of the "Promp t-o-Lympics"**8 pm:**Start**Unti l 10 pm:**Aperitif

*Many functions of interest exhibit weighted summability o
f their coefficients with respect to some dictionary of basis functions.&n
bsp\;**This summability enables efficient s**parse and low-r
ank approximation and ensures that the function can be \;**esti
mated efficiently from samples. \;**This talk presents some fun
damental results on the estimation of sparse and low-rank functions\, like
the \;**weighted Stechkin lemma and the restricted isometry pr
operty\,** \;and \;**introduces simultaneously spars
e and low-rank tensor formats.*

For further information abou t the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20240531T120000 END:VEVENT BEGIN:VEVENT UID:news1671@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240517T172212 DTSTART;TZID=Europe/Zurich:20240527T121500 SUMMARY:Bernoullis Tafelrunde: Valentyna Pavliv (Basel) DESCRIPTION:abstract [t3://file?uid=3669] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20240527T130000 END:VEVENT BEGIN:VEVENT UID:news1687@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240502T134213 DTSTART;TZID=Europe/Zurich:20240524T173000 SUMMARY:BZ Seminar in Analysis: Eric Carlen (Rutgers) DESCRIPTION:A linear map T from the space of n by n matrices to the space o f m by m matrices is a Schwarz map in case T(A^*A) - T(A)^*T(A) is positiv e semidefinite. Evidently every such map T is positive\, but not all posit ive maps are Schwarz maps. On the other hand\, every quantum Markov map (c ompletely positive with T(I) = I) is a Schwarz map but again\, the inclusi on is strict.\\r\\nThis talk will present joint work with Mueller-Hermes a nd Zhang in which duality is exploited to give simple proofs of known and new inequalities for Schwarz maps. It will be shown how these yield cele brated convexity and concavity theorems\, such as those of Lieb and Epstei n as simple corollaries. The ideas may be applied in a more elaborate op erator algebra setting\, but by presenting them in the matrix algebra sett ing\, the talk will require no specialized knowledge as background. X-ALT-DESC:A linear map T from the space of n by n matrices to the space of m by m matrices is a Schwarz map in case T(A^*A) - T(A)^*T(A) is posit ive semidefinite. Evidently every such map T is positive\, but not all pos itive maps are Schwarz maps. On the other hand\, every quantum Markov map (completely positive with T(I) = I) is a Schwarz map but again\, the inclu sion is strict.

\nThis talk will present joint work with Mueller-Her mes and Zhang in which duality is exploited to give simple proofs of known and new \; inequalities for Schwarz maps. It will be shown how these yield celebrated convexity and concavity theorems\, such as those of Lieb and Epstein as simple corollaries. \; The ideas may be applied in a mo re elaborate operator algebra setting\, but by presenting them in the matr ix algebra setting\, the talk will require no specialized knowledge as bac kground. \;

DTEND;TZID=Europe/Zurich:20240524T183000 END:VEVENT BEGIN:VEVENT UID:news1686@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240417T153207 DTSTART;TZID=Europe/Zurich:20240524T160000 SUMMARY:BZ Seminar in Analysis: Robert Seiringer (IST Austria) DESCRIPTION:The Fröhlich polaron and related models of quantum field theor y have played a prominent role in mathematical physics over several decade s. In this talk\, we shall explain recent bounds on the quantum correction s to the (classical) Pekar approximation of the ground state energy of the Fröhlich polaron model in the strong coupling limit\, and their conseque nce on the existence of excited states and the polaron's effective mass. X-ALT-DESC:The Fröhlich polaron and related models of quantum field the ory have played a prominent role in mathematical physics over several deca des. In this talk\, we shall explain recent bounds on the quantum correcti ons to the (classical) Pekar approximation of the ground state energy of t he Fröhlich polaron model in the strong coupling limit\, and their conseq uence on the existence of excited states and the polaron's effective mass.

DTEND;TZID=Europe/Zurich:20240524T170000 END:VEVENT BEGIN:VEVENT UID:news1662@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240502T182134 DTSTART;TZID=Europe/Zurich:20240522T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Christof Sparber (Univer sity of Illinois at Chicago) DESCRIPTION:We consider Schrödinger equations with competing nonlinearitie s in spatial dimensions up to three\, for which global existence holds (i. e. no finite-time blow-up). A typical example is the case of the (focusing -defocusing) cubic-quintic NLS. We recall the notions of energy minimizin g versus action minimizing ground states and show that\, in general\, the two must be considered as nonequivalent. The question of long-time behavio r of solutions\, in particular the problem of ground-state (in-)stability will be discussed using analytical results and numerical simulations. X-ALT-DESC:We consider Schrödinger equations with competing nonlinearit ies in spatial dimensions up to three\, for which global existence holds ( i.e. no finite-time blow-up). A typical example is the case of the (focusi ng-defocusing) cubic-quintic NLS. \;We recall the notions of energy mi nimizing versus action minimizing ground states and show that\, in general \, the two must be considered as nonequivalent. The question of long-time behavior of solutions\, in particular the problem of ground-state (in-)sta bility will be discussed using analytical results and numerical simulation s.

DTEND;TZID=Europe/Zurich:20240522T151500 END:VEVENT BEGIN:VEVENT UID:news1688@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240508T175114 DTSTART;TZID=Europe/Zurich:20240515T151500 SUMMARY:Seminar Analysis and Mathematical Physics: Min Jun Jo (Duke Univers ity) DESCRIPTION:We prove the instantaneous cusp formation from a single corner of the vortex patch solutions. This positively settles the conjecture give n by Cohen-Danchin in Multiscale approximation of vortex patches\, SIAM J . Appl. Math. 60 (2000)\, no. 2\, 477–502. X-ALT-DESC:We prove the instantaneous cusp formation from a single corne
r of the vortex patch solutions. This positively settles the conjecture gi
ven by Cohen-Danchin in \;*Multiscale approximation of vortex patch
es\, SIAM J. Appl. Math. 60 (2000)\, no. 2\, 477–502.*

This talk concerns critical points $u$ of polyconvex energies of the form $f(X) = g(det(X))$\, where $g$ is (uniformly) convex. It is n ot hard to see that\, if $u$ is smooth\, then $\\det(Du)$ is constant. I w ill show that the same result holds for Lipschitz critical points $u$ in t he plane. I will also discuss how to obtain rigidity for approximate solut ions. This is a joint work with A. Guerra.

DTEND;TZID=Europe/Zurich:20240515T150000 END:VEVENT BEGIN:VEVENT UID:news1683@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240502T095624 DTSTART;TZID=Europe/Zurich:20240513T121500 SUMMARY:Bernoullis Tafelrunde: Alessandro Violini (University of Basel) DESCRIPTION:abstract [t3://file?uid=3657] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20240513T130000 END:VEVENT BEGIN:VEVENT UID:news1693@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240508T133217 DTSTART;TZID=Europe/Zurich:20240509T100000 SUMMARY:FANTASY Basel 2024 DESCRIPTION:The Department of Mathematics and Computer Science will once ag ain be present at this year's FANTASY Basel.\\r\\nThe Department's booth w ill feature exhibits from the Databases and Information Systems (DBIS) res earch group\, the Privacy-Enhancing Technologies (PET) research group and the High Performance Computing (HPC) research group.\\r\\nYou will find th e booth in hall 1.1 with the booth number 138. X-ALT-DESC:The Department of Mathematics and Computer Science will once again be present at this year's FANTASY Basel.

\nThe Department's bo oth will feature exhibits from the Databases and Information Systems (DBIS ) research group\, the Privacy-Enhancing Technologies (PET) research group and the High Performance Computing (HPC) research group.

\nYou will find the booth in hall 1.1 with the booth number 138.

DTEND;TZID=Europe/Zurich:20240511T190000 END:VEVENT BEGIN:VEVENT UID:news1689@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240503T101127 DTSTART;TZID=Europe/Zurich:20240508T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Christoph Kehle (ETH Zü rich) DESCRIPTION:Extremal black holes are special types of black holes which hav e exactly zero temperature. I will present a proof that extremal black hol es form in finite time in gravitational collapse of charged matter. In par ticular\, this construction provides a definitive disproof of the “third law” of black hole thermodynamics. I will also present a recent result which shows that extremal black holes arise on the black hole formation th reshold in the moduli space of gravitational collapse. This gives rise to a new conjectural picture of “extremal critical collapse.” This is joi nt work with Ryan Unger (Princeton). X-ALT-DESC:Extremal black holes are special types of black holes which h ave exactly zero temperature. I will present a proof that extremal black h oles form in finite time in gravitational collapse of charged matter. In p articular\, this construction provides a definitive disproof of the “thi rd law” of black hole thermodynamics. I will also present a recent resul t which shows that extremal black holes arise on the black hole formation threshold in the moduli space of gravitational collapse. This gives rise t o a new conjectural picture of “extremal critical collapse.” This is j oint work with Ryan Unger (Princeton).

DTEND;TZID=Europe/Zurich:20240508T160000 END:VEVENT BEGIN:VEVENT UID:news1682@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240429T080016 DTSTART;TZID=Europe/Zurich:20240506T121500 SUMMARY:Bernoullis Tafelrunde: Luca Ferrigno (Roma Tre University) DESCRIPTION:abstract [t3://file?uid=3656] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20240506T130000 END:VEVENT BEGIN:VEVENT UID:news1665@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240429T095246 DTSTART;TZID=Europe/Zurich:20240503T110000 SUMMARY:Seminar in Numerical Analysis: Andreas Veeser (University of Milano ) DESCRIPTION:TBA\\r\\n\\r\\nFor further information about the seminar\, plea se visit this webpage [t3://page?uid=1115]. X-ALT-DESC:TBA

\n\nFor further information about the seminar\, ple ase visit this webpage.

DTEND;TZID=Europe/Zurich:20240503T120000 END:VEVENT BEGIN:VEVENT UID:news1651@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240213T105535 DTSTART;VALUE=DATE:20240503 SUMMARY:Swiss Mathematical Society Doctoral Day 2024 DESCRIPTION:More information can be found here [https://numbertheory.dmi.un ibas.ch/doctoralday2024/]. X-ALT-DESC:More information can be found **here**.

We consider the upscaled linear elasticity problem in the con text of periodic homogenisation in the stationary setting as well as in th e time-dependent regime where the wavelength is much larger than the micro structure. Based on measurements of the deformation of the (macroscopic) b oundary of a body for a given forcing\, the aim is to deduce information o n the geometry of the microstructure. After a general introduction to peri odic homogenisation in the context of linear elasticity\, we are able to p rove for a parametrised microstructure that there exists at least one solu tion of the associated minimisation problem based on the L^2-difference of the measured deformation and the computed deformation for a given paramet er vector. To facilitate the use of gradient-based algorithms\, we derive the Gâteaux derivatives using the Lagrangian method of Céa\, and we pres ent numerical experiments showcasing the functioning of the method.

\n< p>This is joint work with T. Lochner (University of Augsburg).\n\nF or further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20240426T120000 END:VEVENT BEGIN:VEVENT UID:news1666@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240422T090328 DTSTART;TZID=Europe/Zurich:20240424T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Louise Gassot (IRMAR\, R ennes) DESCRIPTION:We focus on the Benjamin-Ono equation on the line with a small dispersion parameter. The goal of this talk is to precisely describe the s olution at all times when the dispersion parameter is small enough. This s olution may exhibit locally rapid oscillations\, which are a manifestation of a dispersive shock. The description involves the multivalued solution of the underlying Burgers equation\, obtained by using the method of chara cteristics. This work is in collaboration with Elliot Blackstone\, Patrick Gérard\, and Peter Miller. X-ALT-DESC:We focus on the Benjamin-Ono equation on the line with a smal l dispersion parameter. The goal of this talk is to precisely describe the solution at all times when the dispersion parameter is small enough. This solution may exhibit locally rapid oscillations\, which are a manifestati on of a dispersive shock. The description involves the multivalued solutio n of the underlying Burgers equation\, obtained by using the method of cha racteristics. This work is in collaboration with Elliot Blackstone\, Patri ck Gérard\, and Peter Miller.

DTEND;TZID=Europe/Zurich:20240424T151500 END:VEVENT BEGIN:VEVENT UID:news1681@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240418T140539 DTSTART;TZID=Europe/Zurich:20240422T121500 SUMMARY:Bernoullis Tafelrunde: Giulia Mescolini (EPFL) DESCRIPTION:abstract [t3://file?uid=3652] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20240422T130000 END:VEVENT BEGIN:VEVENT UID:news1655@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240402T130832 DTSTART;TZID=Europe/Zurich:20240419T110000 SUMMARY:Seminar in Numerical Analysis: Barbara Verfürth (University of Bon n) DESCRIPTION:In the last years\, there has been an increasing interest in ti me-modulated materials to obtain enhanced properties. As mathematical mode l\, we study the classical wave equation with time-dependent coefficient\, which may also include spatial multiscale features. Based on joint work w ith Bernhard Maier\, we present a numerical multiscale method for spatiall y multiscale\, (slowly) time-evolving coefficients. The method is inspired by the Localized Orthogonal Decomposition (LOD) and entails time-dependen t multiscale spaces. We provide a rigorous a priori error analysis for the considered setting. Numerical examples illustrate the theoretical finding s and investigate an adaptive approach for the computation of the time-dep endent basis functions. On the other hand\, we will also briefly discuss t he setting of spatially homogeneous\, temporal multiscale coefficients. (H igher-order) multiscale expansions may help to interpret effective physica l material properties and are numerically illustrated.\\r\\nFor further in formation about the seminar\, please visit this webpage [t3://page?uid=111 5]. X-ALT-DESC:In the last years\, there has been an increasing interest in
time-modulated materials to obtain enhanced properties. As mathematical mo
del\, we study the classical wave equation with time-dependent coefficient
\, which may also include spatial multiscale features.

Based on join
t work with Bernhard Maier\, we present a numerical multiscale method for
spatially multiscale\, (slowly) time-evolving coefficients. The method is
inspired by the Localized Orthogonal Decomposition (LOD) and entails time-
dependent multiscale spaces. We provide a rigorous a priori error analysis
for the considered setting. Numerical examples illustrate the theoretical
findings and investigate an adaptive approach for the computation of the
time-dependent basis functions.

On the other hand\, we will also bri
efly discuss the setting of spatially homogeneous\, temporal multiscale co
efficients. (Higher-order) multiscale expansions may help to interpret eff
ective physical material properties and are numerically illustrated.

For further information about the seminar\, please visit this webpage< /a>.

DTEND;TZID=Europe/Zurich:20240419T120000 END:VEVENT BEGIN:VEVENT UID:news1638@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240328T104112 DTSTART;TZID=Europe/Zurich:20240417T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Anuj Kumar (UC Berkeley) DESCRIPTION:We construct nonunique solutions of the transport equation in t he class $L^\\infty$ in time and $L^r$ in space for divergence free Sobole v vector fields $W^{1\, p}$. We achieve this by introducing two novel idea s: (1) In the construction\, we interweave the scaled copies of the vector field itself. (2) Asynchronous translation of cubes\, which makes the con struction heterogeneous in space. These new ideas allow us to prove nonuni queness in the range of exponents beyond what is available using the metho d of convex integration and sharply matchwith the range of uniqueness of s olutions from Bruè\, Colombo\, De Lellis ’21. X-ALT-DESC:We construct nonunique solutions of the transport equation in the class $L^\\infty$ in time and $L^r$ in space for divergence free Sobo lev vector fields $W^{1\, p}$. We achieve this by introducing two novel id eas: (1) In the construction\, we interweave the scaled copies of the vect or field itself. (2) Asynchronous translation of cubes\, which makes the c onstruction heterogeneous in space. These new ideas allow us to prove nonu niqueness in the range of exponents beyond what is available using the met hod of convex integration and sharply matchwith the range of uniqueness of solutions from Bruè\, Colombo\, De Lellis ’21. \;

DTEND;TZID=Europe/Zurich:20240417T160000 END:VEVENT BEGIN:VEVENT UID:news1680@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240330T103315 DTSTART;TZID=Europe/Zurich:20240415T121500 SUMMARY:Bernoullis Tafelrunde: Beat Zurbuchen (ETHZ) DESCRIPTION:Automorphic forms are central objects in number theory at least since Riemann's proof of the functional equation for the zeta function. F rom a modern point of view\, automorphic forms are functions on certain ho mogeneous spaces which correspond to unitary representations of an adelic symmetry group in a natural way. Langlands conjectured that such represent ations correspond to certain representations of the Galois group. This tal k attempts to explain this correspondence for the special case of Hecke ch aracters and\, if time permits\, modular forms.\\r\\nabstract [t3://file?u id=3646] X-ALT-DESC:Automorphic forms are central objects in number theory at lea st since Riemann's proof of the functional equation for the zeta function. From a modern point of view\, automorphic forms are functions on certain homogeneous spaces which correspond to unitary representations of an adeli c symmetry group in a natural way. Langlands conjectured that such represe ntations correspond to certain representations of the Galois group. This t alk attempts to explain this correspondence for the special case of Hecke characters and\, if time permits\, modular forms.

\n DTEND;TZID=Europe/Zurich:20240415T130000 END:VEVENT BEGIN:VEVENT UID:news1620@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240326T111142 DTSTART;TZID=Europe/Zurich:20240411T161500 SUMMARY:Perlen-Colloquium: Prof. Roman Shvydkoy (University of Illinois at Chicago) DESCRIPTION:Emergence is a phenomenon of formation of collective outcomes i n systems where communication between agents has local range. For a wide range of applications\, such as swarming behavior of animals or exchange o f opinions between individuals\, such outcomes result in a globally aligne d state or congregation of aligned clusters. The classical result of Cucke r and Smale states that alignment is unconditional in groups that facilita te global interactions with non-integrable radial tails. Proving a similar statement for purely local interactions is a challenging mathematical pro blem. There have been several programs of research directed towards unde rstanding the emergent phenomena on micro\, kinetic\, and macro levels of description. In this talk we will mostly focus on the kinetic approach and demonstrate its connection with the classical problem of relaxation for non-perturbative data. X-ALT-DESC:Emergence is a phenomenon of formation of collective outcomes in systems where communication between agents has local \;range. For a wide range of applications\, such as swarming behavior of animals or exc hange of opinions between individuals\, such outcomes result in a globally aligned state or congregation of aligned clusters. The classical result o f Cucker and Smale states that alignment is unconditional in groups that f acilitate global interactions with non-integrable radial tails. Proving a similar statement for purely local interactions is a challenging mathemati cal problem. There have been several programs of research directed \; towards understanding the emergent phenomena on micro\, kinetic\, and macr o levels of description. In this talk we will mostly focus on the kinetic approach and demonstrate \;its connection with the classical problem o f relaxation for non-perturbative data.

END:VEVENT BEGIN:VEVENT UID:news1679@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240320T213152 DTSTART;TZID=Europe/Zurich:20240411T093000 SUMMARY:Rhine Seminar on Transcendence Basel-Freiburg-Strasbourg DESCRIPTION:More information on the website:\\r\\nhttps://rhine-transcenden ce.github.io/meeting5 [https://rhine-transcendence.github.io/meeting5] X-ALT-DESC:More information on the website:

\nhttps://rhine-transcendence.github.io /meeting5

DTEND;TZID=Europe/Zurich:20240411T161000 END:VEVENT BEGIN:VEVENT UID:news1663@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240227T174701 DTSTART;VALUE=DATE:20240411 SUMMARY:Data Science for the Sciences DESCRIPTION:The Data Science for the Sciences (DS4S) conference provides a forum where experts working on different facets of data science — from S tatistical Data Science to Machine Learning and Artificial Intelligence — can meet and exchange ideas. The conference will also cover various to pics from Open Research Data. The April 11-12 event will feature a rich li neup of speakers and panelists from Switzerland and beyond\, as well as po ster sessions.\\r\\nDS4S offers a unique opportunity to bring together res earch actors and stakeholders from cantonal universities\, universities of applied sciences\, federal institutes\, federal agencies\, and corporate R&D around contemporary questions and challenges pertaining to data-driven scientific discovery.\\r\\nDS4S will feature presented contributions on t opics encompassing AI for Medicine\, Physics-Guided Machine Learning for C limate Modelling\, AI & Robotics\, Privacy safeguarding\, Causality and Ne uroscience. Open Research Data will also be put to the fore via a dedicate d session. Among the distinguished speakers\, Giusi Moffa\, head of the St atistical Science Research Group at the Department of Mathematics and Comp uter Science\, will be sharing her insights and expertise.\\r\\nMore infor mation can be found here [https://www.ds4s.ch/]. X-ALT-DESC:The Data Science for the Sciences (DS4S) conference provides a forum where experts working on different facets of data science — from Statistical Data Science to Machine Learning and Artificial Intelligence — can meet and exchange ideas. The conference will also cover various to pics from Open Research Data. The April 11-12 event will feature a rich li neup of speakers and panelists from Switzerland and beyond\, as well as po ster sessions.

\nDS4S offers a unique opportunity to bring together research actors and stakeholders from cantonal universities\, universities of applied sciences\, federal institutes\, federal agencies\, and corpora te R&\;D around contemporary questions and challenges pertaining to dat a-driven scientific discovery.

\nDS4S will feature presented contrib utions on topics encompassing AI for Medicine\, Physics-Guided Machine Lea rning for Climate Modelling\, AI &\; Robotics\, Privacy safeguarding\, Causality and Neuroscience. Open Research Data will also be put to the for e via a dedicated session. Among the distinguished speakers\, Giusi Moffa\ , head of the Statistical Science Research Group at the Department of Math ematics and Computer Science\, will be sharing her insights and expertise.

\nMore information can be found **here**.

The classical Kolmogorov-41 theory of turbulence is based on a set of \; pivotal assumptions on scaling and energy dissipation for solutions satisfying incompressible fluid models. In the early 80's experi mental evidence emerged that pointed to departure from the K41 predictions \, which was attributed to the phenomenon of statistical intermittency.&nb sp\; In this talk we give an overview of the classical results in the subj ect\, relationship of intermittency to the problem of global well-posednes s of the 3D Navier-Stokes system\, and discuss a new approach developed jo intly with A. Cheskidov on how to measure and study intermittency from a r igorous perspective. \; At the center of our discussion will be a new interpretation of an intermittent signal \;described \;by volumetr ic properties of the filtered \;field. \; It provides\, in particu lar\, a systematic approach to the Frisch-Parisi multifractal formalism\, and recasts intermittency from the point of view of information theory.&nb sp\;

DTEND;TZID=Europe/Zurich:20240410T160000 END:VEVENT BEGIN:VEVENT UID:news1658@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240403T150608 DTSTART;TZID=Europe/Zurich:20240408T121500 SUMMARY:Bernoullis Tafelrunde: Christoph Brackenhofer (University of Freibu rg) DESCRIPTION:Period numbers form a countable subset of the complex numbers. One can describe periods via a pairing between (algebraic) de Rham cohomol ogy and singular cohomology or using semi-algebraic sets. A variant are ex ponential periods which admit similar descriptions\, where singular cohomo logy is replaced by rapid decay cohomology and semi-algebraic sets are rep laced by sets definable in a certain o-minimal structure. This talk will b e an introduction to these ideas.\\r\\nabstract [t3://file?uid=3645] X-ALT-DESC:Period numbers form a countable subset of the complex numbers . One can describe periods via a pairing between (algebraic) de Rham cohom ology and singular cohomology or using semi-algebraic sets. A variant are exponential periods which admit similar descriptions\, where singular coho mology is replaced by rapid decay cohomology and semi-algebraic sets are r eplaced by sets definable in a certain o-minimal structure. This talk will be an introduction to these ideas.

\n DTEND;TZID=Europe/Zurich:20240408T130000 END:VEVENT BEGIN:VEVENT UID:news1648@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240323T092733 DTSTART;TZID=Europe/Zurich:20240403T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Vikram Giri (ETH Zürich ) DESCRIPTION:A common issue in convex integration methods (going back to Nas h) is the presence of unwanted high-high frequency interactions. These iss ues can prevent the methods from producing solutions with the optimum "Ons ager" regularity to a given system of PDEs. We will discuss these issues i n the setting of the 2D Euler equations and then discuss a linear Newton i teration designed to get rid of these unwanted interactions in this settin g. We will conclude by discussing applications to other PDEs. This is base d on joint works with Răzvan-Octavian Radu and Mimi Dai. X-ALT-DESC:A common issue in convex integration methods (going back to N ash) is the presence of unwanted high-high frequency interactions. These i ssues can prevent the methods from producing solutions with the optimum "O nsager" regularity to a given system of PDEs. We will discuss these issues in the setting of the 2D Euler equations and then discuss a linear Newton iteration designed to get rid of these unwanted interactions in this sett ing. We will conclude by discussing applications to other PDEs. This is ba sed on joint works with Răzvan-Octavian Radu and Mimi Dai.

DTEND;TZID=Europe/Zurich:20240403T160000 END:VEVENT BEGIN:VEVENT UID:news1645@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240325T134941 DTSTART;TZID=Europe/Zurich:20240327T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Marcello Porta (SISSA) DESCRIPTION:I will discuss the dynamics of many-body Fermi gases\, in the m ean-field regime. I will consider a class of initial data which are close enough to quasi-free states\, with a non-zero pairing matrix. Assuming a suitable semiclassical structure for the initial datum\, expected to hold at low enough energy and that we can establish for translation-invariant states\, I will present a theorem that shows that the many-body evolution of the system can be well approximated by the Hartree-Fock-Bogoliubov equ ation\, a non-linear effective evolution equation describing the coupled dynamics of the reduced one-particle density matrix and of the pairing ma trix. Joint work with Stefano Marcantoni (Nice) and Julien Sabin (Rennes). X-ALT-DESC:I will discuss the dynamics of many-body Fermi gases\, in the mean-field regime. I will consider a class of initial data which are \;close enough to quasi-free states\, with a non-zero pairing matrix. Assu ming a suitable semiclassical structure for the initial datum\, \;expe cted to hold at low enough energy and that we can establish for translatio n-invariant states\, I will present a theorem that shows that \;the ma ny-body evolution of the system can be well approximated by the Hartree-Fo ck-Bogoliubov equation\, a non-linear effective \;evolution equation d escribing the coupled dynamics of the reduced one-particle density matrix and of \;the pairing matrix. Joint work with Stefano Marcantoni (Nice) and Julien Sabin (Rennes).

DTEND;TZID=Europe/Zurich:20240327T153000 END:VEVENT BEGIN:VEVENT UID:news1669@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240312T122038 DTSTART;TZID=Europe/Zurich:20240320T193000 SUMMARY:Artificial Art – AI vs. Human Composers DESCRIPTION:Artificial intelligence is an important topic and has a lasting impact on our society. In an exciting three-part series\, we take a close look at the possibilities of modern AI and its impact on art and society. \\r\\nIn a "game show"\, a human composer competes against an AI compositi on in each of five chapters. The audience hears two versions per chapter a nd piece and chooses which piece was AI and which was human. The pieces ar e composed in the style of Bach\, Chopin\, Messiaen\, Bartok\, Brahms and are played by a human ensemble (the ensemble also does not know which is h uman and which is AI).\\r\\nIn collaboration with the composition classes of the Basel University of Music\, outstanding students compose the "human " part\; the well-known Latvian composer Platons Buravickis "creates" the AI compositions. Fascinating visual arts by Luca Scarzella and Michele Inn ocente will accompany the performance.\\r\\nThe performance will be modera ted and complemented by scientific intermezzi in collaboration with the Re sponsible Digital Society RDS research network at the University of Basel. At the aperitif afterwards\, scientists from AI ethicists to AI medical r esearchers will mingle with the audience and look forward to answering que stions about artificial intelligence.\\r\\nThe event will be opened with a speech by Conradin Cramer\, member of the cantonal government. Please sca n the QR code at the entrance to the Voltahalle to take part in the voting via smartphone.\\r\\nRegistration and tickets\\r\\nEarly Bird-Tickets [ht tps://www.kulturticket.ch/22997/interfinity/event/726] "Artificial Art - H uman Composers vs. AI" (incl. aperitif): 30 CHF normal price 20 CHF reduce d (under 28 years). Free choice of seats. X-ALT-DESC:**Artificial intelligence is an important topic and has
a lasting impact on our society. In an exciting three-part series\, we ta
ke a close look at the possibilities of modern AI and its impact on art an
d society.**

In a "game show"\, a human composer competes a gainst an AI composition in each of five chapters. The audience hears two versions per chapter and piece and chooses which piece was AI and which wa s human. The pieces are composed in the style of Bach\, Chopin\, Messiaen\ , Bartok\, Brahms and are played by a human ensemble (the ensemble also do es not know which is human and which is AI).

\nIn collaboration with the composition classes of the Basel University of Music\, outstanding st udents compose the "human" part\; the well-known Latvian composer Platons Buravickis "creates" the AI compositions. Fascinating visual arts by Luca Scarzella and Michele Innocente will accompany the performance.

\nTh e performance will be moderated and complemented by scientific intermezzi in collaboration with the Responsible Digital Society RDS research network at the University of Basel. At the aperitif afterwards\, scientists from AI ethicists to AI medical researchers will mingle with the audience and l ook forward to answering questions about artificial intelligence.

\nThe event will be opened with a speech by Conradin Cramer\, member of the cantonal government. Please scan the QR code at the entrance to the Voltah alle to take part in the voting via smartphone.

\nEarly Bird-Tickets "Artificial Art - Human Composers vs. AI" (incl. aperitif): 30 CHF normal price 20 CHF reduced (under 28 years). Fre e choice of seats.

END:VEVENT BEGIN:VEVENT UID:news1641@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240205T090917 DTSTART;TZID=Europe/Zurich:20240320T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Norbert J. Mauser (WPI and MMM c/o Univ. Wien) DESCRIPTION:The Pauli-Poisswell equation models fast moving charges in\\r\\ nsemiclassical semi-relativistic quantum dynamics. It is at the\\r\\ncente r of a hierarchy of models from the Dirac-Maxwell equation to\\r\\nthe Eul er-Poisson equation that are linked by asymptotic analysis of\\r\\nsmall p arameters such as Planck constant or inverse speed of light.\\r\\nWe discu ss the models and their application in plasma and\\r\\naccelerator physics as well as the many mathematical problems they\\r\\npose. X-ALT-DESC:The Pauli-Poisswell equation models fast moving charges in

\nsemiclassical semi-relativistic quantum dynamics. It is at the

\ncenter of a hierarchy of models from the Dirac-Maxwell equation to

\ nthe Euler-Poisson equation that are linked by asymptotic analysis of\n

small parameters such as Planck constant or inverse speed of light.

\nWe discuss the models and their application in plasma and

\naccelerator physics as well as the many mathematical problems they

\n< p>pose. DTEND;TZID=Europe/Zurich:20240320T161500 END:VEVENT BEGIN:VEVENT UID:news1643@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240326T134216 DTSTART;TZID=Europe/Zurich:20240318T121500 SUMMARY:Bernoullis Tafelrunde: Jinghao Cao (ETH Zürich) DESCRIPTION:abstract [t3://file?uid=3583] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20240318T130000 END:VEVENT BEGIN:VEVENT UID:news1584@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240223T103733 DTSTART;TZID=Europe/Zurich:20240314T161500 SUMMARY:Perlen-Colloquium: Prof. Jean-Pierre Eckmann (University of Geneva) DESCRIPTION:A cylinder will roll down an inclined plane in a straight line. A cone will wiggle along a circle on that plane and then will stop rollin g. We ask the inverse question: For which curves drawn on the inclined pla ne $\\real^2$ can one chisel a shape that will roll downhill following pre cisely this prescribed curve and its translationally repeated copies? Thi s is a nice\, and easy to understand problem\, but the solution is quite i nteresting. (Based on work mostly with Y. Sobolev and T. Tlusty. After a Nature paper\, Solid-body trajectoids shaped to roll along desired pathway s\, August 2023.) X-ALT-DESC:A cylinder will roll down an inclined plane in a straight lin
e. A cone will

wiggle along a circle on that plane and then will sto
p rolling.

We ask the inverse question: For which curves drawn on th
e inclined plane

$\\real^2$ can one chisel a shape that will roll do
wnhill following precisely

this prescribed curve and its translation
ally repeated copies?

This is a nice\, and easy to understand
problem\, but the solution is quite

interesting.

(Base
d on work mostly with Y. Sobolev and T. Tlusty. After a Nature paper\,

Solid-body trajectoids shaped to roll along desired pathways\, August 2
023.)

While "Landau damping" is regarded as an important effect in the dynamics of hot\, collisionless plasmas\, its mathematical understandi ng is still in its infancy. This talk presents a recent nonlinear stabilit y result in this context. Starting with a discussion of stabilizing mechan isms in the linearized Vlasov-Poisson equations near a class of homogeneou s equilibria on R^3\, we will see how both oscillatory and damping effects arise\, and sketch how these mechanisms imply a nonlinear stability resul t in the specific setting of the Poisson equilibrium. This is based on joi nt work with A. Ionescu\, B. Pausader and X. Wang.

DTEND;TZID=Europe/Zurich:20240306T160000 END:VEVENT BEGIN:VEVENT UID:news1642@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240213T153738 DTSTART;TZID=Europe/Zurich:20240304T121500 SUMMARY:Bernoullis Tafelrunde: Tobias Bisang (University of Basel) DESCRIPTION:abstract [t3://file?uid=3604] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20240304T130000 END:VEVENT BEGIN:VEVENT UID:news1624@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240123T123011 DTSTART;TZID=Europe/Zurich:20240202T160000 SUMMARY:[in German] 20 Jahre Informatikstudium an der Universität Basel DESCRIPTION:Das Informatikstudium in Basel feiert sein 20-jähriges Jubilä um. Gleichzeitig befindet sich die Disziplin in einem rasanten Wandel. Aus diesem Grund veranstaltet das Departement Mathematik und Informatik (DMI) zusammen mit dem Forschungsnetzwerk Responsible Digital Society (RDS) [ht tps://rds.unibas.ch/de/] der Universität Basel eine Veranstaltung zur "Zu kunft der Informatik in Forschung und Lehre".\\r\\nProgramm: Begrüssung P rof. Jiří Černý\, Vorsteher Departement Mathematik und Informatik Grus swort der Rektorin Prof. Dr. Dr. h.c. mult. Andrea Schenker-Wicki\\r\\nTei l 1: Zukunft der Informatik-Forschung - Vortrag Prof. Dr. Joachim Buhmann\ , ETH Zürich\, Institut für Maschinelles Lernen - Vortrag Dr. Yannic Kil cher\, Gründer und CTO Deep Judge\, Gründer Open Assistant\, Youtuber\\r \\nTeil 2: Zukunft der Informatik-Lehre Podiumsdiskussion mit - Prof. Dr. Joachim Buhmann\, ETH Zürich\, Institut für Maschinelles Lernen - Brigit te Jäggi\, Rektorin Gymnasium Muttenz - Dr. Yannic Kilcher\, Gründer und CTO Deep Judge\, Gründer Open Assistant\, Youtuber - Dr. Gabriele Röger \, Dozentin am Dep. Mathematik und Informatik\, Universität Basel - Debor ah Strub\, Leiterin Digitalinitiative be-digital der Handelskammer beider Basel Moderation: Prof. Dr. Nadja Braun Binder\, Vizerektorin People & Cul ture\, Universität Basel\\r\\nIm Anschluss sind Sie herzlich zu einem Ap éro eingeladen. X-ALT-DESC:Das Informatikstudium in Basel feiert sein 20-jähriges Jubil äum. Gleichzeitig befindet sich die Disziplin in einem rasanten Wandel. A us diesem Grund veranstaltet das Departement Mathematik und Informatik (DM I) zusammen mit dem Forschungsnetzwerk Responsible Digital Society (RDS) der Universität Basel eine Veranst altung zur "Zukunft der Informatik in Forschung und Lehre".

\n

Begrüssung Prof. Jiří Černý\, Vorst
eher Departement Mathematik und Informatik

Grusswort der Rektorin Pr
of. Dr. Dr. h.c. mult. Andrea Schenker-Wicki

**Teil 1: Zukun
ft der Informatik-Forschung**

- Vortrag Prof. Dr. Joachim Buh
mann\, ETH Zürich\, Institut für Maschinelles Lernen

- Vortrag Dr.
Yannic Kilcher\, Gründer und CTO Deep Judge\, Gründer Open Assistant\,
Youtuber

**Teil 2: Zukunft der Informatik-Lehre**

Podiumsdiskussion mit

- Prof. Dr. Joachim Buhmann\, ETH Zürich\,
Institut für Maschinelles Lernen

- Brigitte Jäggi\, Rektorin Gymn
asium Muttenz

- Dr. Yannic Kilcher\, Gründer und CTO Deep Judge\, G
ründer Open Assistant\, Youtuber

- Dr. Gabriele Röger\, Dozentin a
m Dep. Mathematik und Informatik\, Universität Basel

- Deborah Stru
b\, Leiterin Digitalinitiative be-digital der Handelskammer beider Basel** Moderation: Prof. Dr. Nadja Braun Binder\, Vizerektorin People &\;
Culture\, Universität Basel**

Im Anschluss sind Sie herzlich zu ei nem Apéro eingeladen.

END:VEVENT BEGIN:VEVENT UID:news1606@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231211T155306 DTSTART;TZID=Europe/Zurich:20231218T121500 SUMMARY:Bernoullis Tafelrunde: Jim Zhao (University of Basel) DESCRIPTION:abstract [t3://file?uid=3529] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231218T130000 END:VEVENT BEGIN:VEVENT UID:news1623@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231208T101646 DTSTART;TZID=Europe/Zurich:20231215T173000 SUMMARY:BZ Seminar in Analysis: Marcello Porta (SISSA Trieste) DESCRIPTION:I will discuss the emergence of effective evolution equations f or the dynamics of N interacting quantum particles\, of fermionic type\, s tarting from the many-body Schroedinger equation. In the last years\, ther e has been a lot of progress in the derivation of the Hartree-Fock (HF) eq uation\, a nonlinear evolution equation for weakly correlated initial stat es\, in the mean-field regime. There\, one typically considers initially c onfined particles\, with density that grows linearly with N. In this talk\ , I will discuss the case of extended systems\, at fixed particle density. The HF dynamics arises after extracting the mean-field behavior at the lo cal scale\, which is made possible thanks to the propagation of a suitable local semiclassical structure of the initial datum along the HF flow. In the second part of the talk I will adapt the strategy to the case of many- body systems where the number of particles is not fixed\, in the mean-fiel d regime. I will present the rigorous derivation of the Hartree-Fock-Bogol iubov equation\, a nonlinear equation for the dynamics of initial data cha racterized by a nonzero pairing density\, relevant for the description of superconductors in BCS theory. Based on joint works with L. Fresta and B. Schlein\, and with S. Marcantoni and J. Sabin. X-ALT-DESC:I will discuss the emergence of effective evolution equations for the dynamics of N interacting quantum particles\, of fermionic type\, starting from the many-body Schroedinger equation. In the last years\, th ere has been a lot of progress in the derivation of the Hartree-Fock (HF) equation\, a nonlinear evolution equation for weakly correlated initial st ates\, in the mean-field regime. There\, one typically considers initially confined particles\, with density that grows linearly with N. In this tal k\, I will discuss the case of extended systems\, at fixed particle densit y. The HF dynamics arises after extracting the mean-field behavior at the local scale\, which is made possible thanks to the propagation of a suitab le local semiclassical structure of the initial datum along the HF flow. I n the second part of the talk I will adapt the strategy to the case of man y-body systems where the number of particles is not fixed\, in the mean-fi eld regime. I will present the rigorous derivation of the Hartree-Fock-Bog oliubov equation\, a nonlinear equation for the dynamics of initial data c haracterized by a nonzero pairing density\, relevant for the description o f superconductors in BCS theory. Based on joint works with L. Fresta and B . Schlein\, and with S. Marcantoni and J. Sabin.

DTEND;TZID=Europe/Zurich:20231215T183000 END:VEVENT BEGIN:VEVENT UID:news1622@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231208T101358 DTSTART;TZID=Europe/Zurich:20231215T160000 SUMMARY:BZ Seminar in Analysis: Svitlana Mayboroda (ETH Zürich) DESCRIPTION:We construct the harmonic measure associated to partially refle ctive Brownian motion (that is\, Robin boundary data) and demonstrate that its behavior is surprisingly different from the Dirichlet analogue. In pa rticular\, contrary to the traditional setting and to some predictions in physics literature\, it is absolutely continuous with respect to the Hausd orff measure for a large class of operators and domains. X-ALT-DESC:We construct the harmonic measure associated to partially ref lective Brownian motion (that is\, Robin boundary data) and demonstrate th at its behavior is surprisingly different from the Dirichlet analogue. In particular\, contrary to the traditional setting and to some predictions i n physics literature\, it is absolutely continuous with respect to the Hau sdorff measure for a large class of operators and domains. \;

DTEND;TZID=Europe/Zurich:20231215T170000 END:VEVENT BEGIN:VEVENT UID:news1550@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231204T091610 DTSTART;TZID=Europe/Zurich:20231215T110000 SUMMARY:Seminar in Numerical Analysis: Caroline Geiersbach (WIAS Berlin) DESCRIPTION:Many problems in shape optimization involve constraints in the form of one or more partial differential equations. In practice\, the mate rial properties of the underlying shape on which a PDE is defined are not known exactly\; it is natural to use a probability distribution based on e mpirical measurements and incorporate this information when designing an o ptimal shape. Additionally\, one might wish to obtain a shape that is robu st in its response to certain external inputs\, such as forces. It is help ful to view shape optimization problems subject to uncertainty through the lens of stochastic optimization\, where a wealth of theory and algorithms already exist for finite-dimensional problems. The focus will be on the a lgorithmic handling of these problems in the case of a high stochastic dim ension. Stochastic approximation\, which dynamically samples from the stoc hastic space over the course of iterations\, is favored in this case\, and we show how these methods can be applied to shape optimization. We study the classical stochastic gradient method\, which was introduced in 1951 by Robbins and Monro and is widely used in machine learning. In particular\, we investigate its application to infinite-dimensional shape manifolds. F urther\, we present numerical examples showing the performance of the meth od\, also in combination with the augmented Lagrangian method for problems with geometric constraints. \\r\\nJoint work with: Kathrin Welker\, Este fania Loayza-Romero\, Tim Suchan\\r\\n\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Many problems in shape optimization involve constraints in th e form of one or more partial differential equations. In practice\, the ma terial properties of the underlying shape on which a PDE is defined are no t known exactly\; it is natural to use a probability distribution based on empirical measurements and incorporate this information when designing an optimal shape. Additionally\, one might wish to obtain a shape that is ro bust in its response to certain external inputs\, such as forces. It is he lpful to view shape optimization problems subject to uncertainty through t he lens of stochastic optimization\, where a wealth of theory and algorith ms already exist for finite-dimensional problems. The focus will be on the algorithmic handling of these problems in the case of a high stochastic d imension. Stochastic approximation\, which dynamically samples from the st ochastic space over the course of iterations\, is favored in this case\, a nd we show how these methods can be applied to shape optimization. We stud y the classical stochastic gradient method\, which was introduced in 1951 by Robbins and Monro and is widely used in machine learning. In particular \, we investigate its application to infinite-dimensional shape manifolds. Further\, we present numerical examples showing the performance of the me thod\, also in combination with the augmented Lagrangian method for proble ms with geometric constraints. \;

\nJoint work with: Kathrin Wel ker\, Estefania Loayza-Romero\, Tim Suchan

\n\nFor further informati on about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20231215T120000 END:VEVENT BEGIN:VEVENT UID:news1611@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231107T040532 DTSTART;TZID=Europe/Zurich:20231213T151500 SUMMARY:Seminar Analysis and Mathematical Physics: Theodore Drivas (Stony B rook University) DESCRIPTION:We will discuss aspects of the global picture of 2D fluids. Ste ady states\, deterioration of regularity for time dependent solutions as w ell as for the Lagrangian flowmap\, as well as conjectural pictures about the weak-* attractor and generic behavior by Shnirelman and Sverak. \\r\\ nNotice the special time! X-ALT-DESC:We will discuss aspects of the global picture of 2D fluids. S teady states\, deterioration of regularity for time dependent solutions as well as for the Lagrangian flowmap\, as well as conjectural pictures abou t the weak-* attractor and generic behavior by Shnirelman and Sverak. \;

\n**Notice the special time!**

A posteriori estimates enable to certify the error committed in a numerical simulation. In particular\, the equilibrated flux reconstru ction technique yields a guaranteed error upper bound\, where the flux\, o btained by a local postprocessing\, is of independent interest since it is always locally conservative. In this talk\, we tailor this methodology to model nonlinear and time-dependent problems to obtain estimates that are robust\, i.e.\, of quality independent of the strength of the nonlineariti es and the final time. These estimates include\, and build on\, common ite rative linearization schemes such as Zarantonello\, Picard\, Newton\, or M - and L-ones. We first consider steady problems and conceive two settings: we either augment the energy difference by the discretization error of th e current linearization step\, or we design iteration-dependent norms that feature weights given by the current iterate. We then turn to unsteady pr oblems. Here we first consider the linear heat equation and finally move t o the Richards one\, that is doubly nonlinear and exhibits both parabolic –hyperbolic and parabolic–elliptic degeneracies. Robustness with respe ct to the final time and local efficiency in both time and space are addre ssed here. Numerical experiments illustrate the theoretical findings all a long the presentation. Details can be found in [1-4].

\nA. Ern\, I.
Smears\, M. Vohralík\, Guaranteed\, locally space-time efficient\, and po
lynomial-degree robust a posteriori error estimates for high-order discret
izations of parabolic problems\, *SIAM J. Numer. Anal.***55<
/strong> (2017)\, 2811–2834.**

A. Harnist\, K. Mitra\, A. Rappapor t\, M. Vohralík\, Robust energy a posteriori estimates for nonlinear elli ptic problems\, HAL Preprint \;04033438\, 2023.

\nK. Mitra\, M.
Vohralík\, A posteriori error estimates for the Richards equation\, *M
ath. Comp.* (2024)\, accepted for publication.

K. Mitra\, M. V ohralík\, Guaranteed\, locally efficient\, and robust a posteriori estima tes for nonlinear elliptic problems in iteration-dependent norms. An ortho gonal decomposition result based on iterative linearization\, HAL Preprint \;04156711\, 2023.

\n\nFor further information about the semina r\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20231208T120000 END:VEVENT BEGIN:VEVENT UID:news1588@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231201T140131 DTSTART;TZID=Europe/Zurich:20231206T141500 SUMMARY:Seminar Analysis and Mathematical Physics: David Meyer (Universitä t Münster) DESCRIPTION:A vortex ring is a solution of the axisymmetric Euler equations consisting of some torus of concentrated vorticity. Motivated by the appe arance of Vortex rings as bubble rings\, we study vortex rings with surfac e tension at the interface. We show the existence of traveling wave soluti ons. In particular\, our construction also justifies the existence of so-c alled hollow vortex rings\, where the vorticity is a measure concentrated on the interface. X-ALT-DESC:A vortex ring is a solution of the axisymmetric Euler equatio ns consisting of some torus of concentrated vorticity. Motivated by the ap pearance of Vortex rings as bubble rings\, we study vortex rings with surf ace tension at the interface. We show the existence of traveling wave solu tions. In particular\, our construction also justifies the existence of so -called hollow vortex rings\, where the vorticity is a measure concentrate d on the interface.

DTEND;TZID=Europe/Zurich:20231206T160000 END:VEVENT BEGIN:VEVENT UID:news1580@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231114T180149 DTSTART;TZID=Europe/Zurich:20231129T134500 SUMMARY:Seminar Analysis and Mathematical Physics: Sergio Simonella (Univer sity of Roma La Sapienza) DESCRIPTION:Boltzmann equation\, hard sphere systems and their small and la rge deviations X-ALT-DESC:Boltzmann equation\, hard sphere systems and their small and lar ge deviations DTEND;TZID=Europe/Zurich:20230929T163000 END:VEVENT BEGIN:VEVENT UID:news1614@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231114T180522 DTSTART;TZID=Europe/Zurich:20231129T134500 SUMMARY:Seminar Analysis and Mathematical Physics: Sergio Simonella (Univer sity of Roma La Sapienza) DESCRIPTION:https://nccr-swissmap.ch/news-and-events/news/next-kinetic-theo ry-seminar-29th-nov-prof-sergio-simonella-university-roma-la-sapienza X-ALT-DESC:https://nccr-swissmap.ch/news-and-events/news/next-kinetic-th eory-seminar-29th-nov-prof-sergio-simonella-university-roma-la-sapienza

DTEND;TZID=Europe/Zurich:20231129T163000 END:VEVENT BEGIN:VEVENT UID:news1578@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231123T195056 DTSTART;TZID=Europe/Zurich:20231123T161500 SUMMARY:DMI Colloquium: Tomasz Kacprzak (Swiss Data Science Center\, Paul S cherrer Institute/ETH Zurich) DESCRIPTION:Tomasz Kacprzak is a Senior Scientist at ETH Zurich and a Senio r Data Scientist at the Swiss Data Science Center at the Paul Scherrer Ins titute. He obtained his PhD in Physics and Astronomy from the University C ollege London\, as well as previously a MSc in Machine Learning from the s ame university. His focus is on interdisciplinary science in physics and a rtificial intelligence\, in particular on applications of machine learning and high-performance computing to solve otherwise-untraceable problems in physics and cosmology. On the cosmology side\, he is involved in the Dark Energy Survey project\, the Euclid satellite\, and the Square Kilometer A rray. More information here [http://tomaszkacprzak.github.io].\\r\\nAbstra ct: The upcoming mega-telescopes\, such as European Space Agency’s recen tly launched Euclid satellite\, and the upcoming radio Square Kilometer Ar ray (SKA)\, will provide images of our universe over 10 billion years of c osmic history\, and enable us to study its evolution with unprecedented le vel of detail. In the framework of simulations-based inference\, the big t elescopes deliver a throve of high-resolution observations and big compute rs provide the feature-rich numerical theory prediction. By using AI train ed on simulations and performing inference on observations\, we will be ab le us to differentiate between complex models of dark matter\, dark energy \, modified gravity\, and astrophysics\; a task unattainable by classical pen-and-paper analysis. This way\, big computers paired with big telescope s will enable next breakthroughs in our understanding of the universe. In this talk\, I will review the current and future applications of HPC and A I in cosmology in astrophysics\, focusing on areas where they already play an indispensable role. I will also present a number of yet-unsolved probl ems in data science\, the solutions to which are critical for enabling nex t generation measurements in cosmology. X-ALT-DESC:Tomasz Kacprzak is a Senior Scientist at ETH Zurich and a Sen
ior Data Scientist at the Swiss Data Science Center at the Paul Scherrer I
nstitute. He obtained his PhD in Physics and Astronomy from the University
College London\, as well as previously a MSc in Machine Learning from the
same university. His focus is on interdisciplinary science in physics and
artificial intelligence\, in particular on applications of machine learni
ng and high-performance computing to solve otherwise-untraceable problems
in physics and cosmology. On the cosmology side\, he is involved in the Da
rk Energy Survey project\, the Euclid satellite\, and the Square Kilometer
Array.

More information h
ere.

Abstract:

The upcoming mega-telescopes\, such as Eu
ropean Space Agency’s recently launched Euclid satellite\, and the upcom
ing radio Square Kilometer Array (SKA)\, will provide images of our univer
se over 10 billion years of cosmic history\, and enable us to study its ev
olution with unprecedented level of detail. In the framework of simulation
s-based inference\, the big telescopes deliver a throve of high-resolution
observations and big computers provide the feature-rich numerical theory
prediction. By using AI trained on simulations and performing inference on
observations\, we will be able us to differentiate between complex models
of dark matter\, dark energy\, modified gravity\, and astrophysics\; a ta
sk unattainable by classical pen-and-paper analysis. This way\, big comput
ers paired with big telescopes will enable next breakthroughs in our under
standing of the universe. In this talk\, I will review the current and fut
ure applications of HPC and AI in cosmology in astrophysics\, focusing on
areas where they already play an indispensable role. I will also present a
number of yet-unsolved problems in data science\, the solutions to which
are critical for enabling next generation measurements in cosmology.

The study of the Schrödinger equation in dimension one with
a nonlinear point interaction has been the focus of research over the past
few decades. In this seminar\, we talk about a work on deriving this part
ial differential equation as the effective dynamics of N identical bosons
in one dimension.

We assume introducing a tiny impurity located at t
he origin and considering that the interaction between every pair of boson
s is mediated by the impurity through a three-body interaction. Moreover\,
by assuming short-range scaling and choosing an initial fully condensed s
tate\, we prove convergence of one-particle density operators in the trace
-class topology. This is the first derivation of the so-called nonlinear d
elta model. This research is a collaborative work with Prof. Riccardo Adam
i.

Further information about the Info Day Bachelor you can find here (in German).

END:VEVENT BEGIN:VEVENT UID:news1589@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231031T155120 DTSTART;TZID=Europe/Zurich:20231115T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Marc Nualart (Imperial C ollege London) DESCRIPTION:In this talk we consider the long-time behavior of solutions to the two dimensional non-homogeneous Euler equations under the Boussinesq approximation posed on a periodic channel. We prove inviscid damping for the linearized equations around the stably stratified Couette flow using stationary-phase methods of oscillatory integrals. We discuss how these os cillatory integrals arise\, what are the main regularity requirements to carry out the stationary-phase arguments\, and how to achieve such regula rities. X-ALT-DESC:In this talk we consider the long-time behavior of solutions to the two dimensional non-homogeneous Euler equations under the Boussines q approximation posed on a periodic channel. We prove inviscid damping &nb sp\;for the linearized equations around the stably stratified Couette flow using stationary-phase methods of oscillatory integrals. We discuss how t hese oscillatory integrals arise\, \;what are the main regularity req uirements to carry out the stationary-phase arguments\, and how to achieve such regularities.

DTEND;TZID=Europe/Zurich:20231115T160000 END:VEVENT BEGIN:VEVENT UID:news1612@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231107T100752 DTSTART;TZID=Europe/Zurich:20231113T121500 SUMMARY:Bernoullis Tafelrunde: Marco Inversi (University of Basel) DESCRIPTION:abstract [t3://file?uid=3519] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231113T130000 END:VEVENT BEGIN:VEVENT UID:news1592@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231016T134254 DTSTART;TZID=Europe/Zurich:20231110T140000 SUMMARY:Number Theory Days 2023 DESCRIPTION:You can find detailed information about the conference here: ht tps://numbertheory.dmi.unibas.ch/ntd2023/index.html [https://numbertheory. dmi.unibas.ch/ntd2023/index.html].\\r\\nRegistration is free but mandatory . To register\, please fill out the registration [https://forms.gle/FWiTsA M5mP6MQhjFA]. X-ALT-DESC:You can find detailed information about the conference here: https://nu mbertheory.dmi.unibas.ch/ntd2023/index.html.

\nRegistration is f ree but mandatory. To register\, please fill out the registration.

DTEND;TZID=Europe/Zurich:20231111T113000 END:VEVENT BEGIN:VEVENT UID:news1544@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230922T165627 DTSTART;TZID=Europe/Zurich:20231110T110000 SUMMARY:Seminar in Numerical Analysis: Larisa Beilina (University of Göteb org) DESCRIPTION:An adaptive finite element/finite difference domain decompositi on method for solution of time-dependent Maxwell's equations for electric field in conductive media will be presented. This method is applied for r econstruction of dielectric permittivity and conductivity functions using time-dependent scattered data of electric field at the boundary of the do main.\\r\\nAll reconstruction algorithms are based on optimization approac h for finding of stationary point of the Lagrangian. Derivation of a poste riori error estimates for the regularized solution and Tikhonov functional will be presented. Based on these estimates adaptive reconstruction alg orithms are developed. Computational tests will show robustness of propo sed algorithms in 3D.\\r\\n\\r\\nFor further information about the seminar \, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:An adaptive finite element/finite difference domain decomposi tion \;method for solution of time-dependent Maxwell's equations for e lectric field in conductive media will be presented. This method is applie d for reconstruction of dielectric permittivity and conductivity \;fun ctions using time-dependent scattered data of electric field at the bounda ry of the domain.

\nAll reconstruction algorithms are based on optim ization approach for finding of stationary point of the Lagrangian. Deriva tion of a posteriori error estimates for the regularized solution and Tikh onov functional will be presented. \;Based on these estimates adaptiv e reconstruction algorithms are developed. \;Computational tests will show robustness of proposed algorithms in 3D.

\n\nFor further infor mation about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20231110T120000 END:VEVENT BEGIN:VEVENT UID:news1605@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231030T110327 DTSTART;TZID=Europe/Zurich:20231109T110000 SUMMARY:Learning linear models in-context with transformers DESCRIPTION:Attention-based neural network sequence models such as transfor mers have the capacity to act as supervised learning algorithms: They can take as input a sequence of labeled examples and output predictions for un labeled test examples. Indeed\, recent work by Garg et al. has shown tha t when training GPT2 architectures over random instances of linear regress ion problems\, these models' predictions mimic those of ordinary least squ ares. Towards understanding the mechanisms underlying this phenomenon\, we investigate the dynamics of in-context learning of linear predictors fo r a transformer with a single linear self-attention layer trained by gradi ent flow. We show that despite the non-convexity of the underlying optim ization problem\, gradient flow with a random initialization finds a globa l minimum of the objective function. Moreover\, when given a prompt of l abeled examples from a new linear prediction task\, the trained transforme r achieves small prediction error on unlabeled test examples. We further characterize the behavior of the trained transformer under distribution s hifts. \\r\\nSpencer Frei is an Assistant Professor of Statistics at UC Davis. He is broadly interested in machine learning\, statistics\, and opt imization\, with a particular interest in understanding and improving deep learning. Prior to joining UC Davis\, he was a postdoctoral fellow at th e Simons Institute for the Theory of Computing at UC Berkeley\, mentored b y Peter Bartlett and Bin Yu as a part of the NSF/Simons Collaboration on t he Theoretical Foundations of Deep Learning. He completed his PhD in Stati stics at UCLA under the supervision of Quanquan Gu and Ying Nian Wu. \\r\ \nhttps://spencerfrei.github.io/ [https://spencerfrei.github.io/] X-ALT-DESC:Attention-based neural network sequence models such as transf ormers have the capacity to act as supervised learning algorithms: They ca n take as input a sequence of labeled examples and output predictions for unlabeled test examples. \; Indeed\, recent work by Garg et al. has sh own that when training GPT2 architectures over random instances of linear regression problems\, these models' predictions mimic those of ordinary le ast squares. \; Towards understanding the mechanisms underlying this p henomenon\, we investigate the dynamics of in-context learning of linear p redictors for a transformer with a single linear self-attention layer trai ned by gradient flow. \; We show that despite the non-convexity of the underlying optimization problem\, gradient flow with a random initializat ion finds a global minimum of the objective function. \; Moreover\, wh en given a prompt of labeled examples from a new linear prediction task\, the trained transformer achieves small prediction error on unlabeled test examples. \; We further characterize the behavior of the trained trans former under distribution shifts. \;

\nSpencer Frei is \;an Assistant Professor of Statistics at UC Davis. He is broadly interested in machine learning\, statistics\, and optimization\, with a particular inte rest in understanding and improving deep learning. \;Prior to joining UC Davis\, he was a postdoctoral fellow at the Simons Institute for the Th eory of Computing at UC Berkeley\, mentored by Peter Bartlett and Bin Yu a s a part of the NSF/Simons Collaboration on the Theoretical Foundations of Deep Learning. He completed his PhD in Statistics at UCLA under the super vision of Quanquan Gu and Ying Nian Wu. \;

\nhttps://spencerfrei.github.io/

END:VEVENT BEGIN:VEVENT UID:news1602@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231027T193133 DTSTART;TZID=Europe/Zurich:20231108T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Gabriele Bocchi (Univers ità degli Studi di Roma Tor Vergata) DESCRIPTION:We analyze an optimal transport problem with additional entropi c cost evaluated along curves in the Wasserstein space which join two prob ability measures m_0 and m_1. The effect of the additional entropy functio nal results into an elliptic regularization for the (so-called) Kantorovic h potentials of the dual problem.\\r\\nAssuming the initial and terminal m easures to have densities\, we prove that the optimal curve remains positi ve and locally bounded in time. We focus on the case that the transport pr oblem is set on a compact Riemannian manifold with Ricci curvature bounded below.\\r\\nThe approach follows ideas introduced by P.L. Lions in the th eory of mean-field games about optimization problems with penalizing conge stion terms. Crucial steps of our strategy include displacement convexity properties in the Eulerian approach and the analysis of distributional sub solutions to Hamilton-Jacobi equations.\\r\\nThe result provides a smooth approximation of Wasserstein-2 geodesics. X-ALT-DESC:We analyze an optimal transport problem with additional entro pic cost evaluated along curves in the Wasserstein space which join two pr obability measures m_0 and m_1. The effect of the additional entropy funct ional results into an elliptic regularization for the (so-called) Kantorov ich potentials of the dual problem.

\nAssuming the initial and termi nal measures to have densities\, we prove that the optimal curve remains p ositive and locally bounded in time. We focus on the case that the transpo rt problem is set on a compact Riemannian manifold with Ricci curvature bo unded below.

\nThe approach follows ideas introduced by P.L. Lions i n the theory of mean-field games about optimization problems with penalizi ng congestion terms. Crucial steps of our strategy include displacement co nvexity properties in the Eulerian approach and the analysis of distributi onal subsolutions to Hamilton-Jacobi equations.

\nThe result provide s a smooth approximation of Wasserstein-2 geodesics.

DTEND;TZID=Europe/Zurich:20231108T160000 END:VEVENT BEGIN:VEVENT UID:news1597@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231106T131435 DTSTART;TZID=Europe/Zurich:20231107T121500 SUMMARY:Bernoullis Tafelrunde: Gabriele Bocchi (Tor Vergata) DESCRIPTION:abstract [t3://file?uid=3515] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231107T130000 END:VEVENT BEGIN:VEVENT UID:news1595@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231027T075510 DTSTART;TZID=Europe/Zurich:20231106T180000 SUMMARY:Wozu brauchen wir immer mehr Daten? / Pourquoi toujours plus de don nées ? DESCRIPTION:The University of Basel and the French Embassy in Switzerland a re organising a colloquium with panel discussion on the topic "More and mo re data: Opportunities and Risks in Health Care. Ethical\, social\, legal and (educational) scientific perspectives."\\r\\nThe event is bilingual Ge rman-French with simultaneous translation.\\r\\nFor more information see: https://www.unibas.ch/en/News-Events/Events.html?id=e2aa9031-b2d0-49ca-a37 9-0b08b7f6759b [https://www.unibas.ch/en/News-Events/Events.html?id=e2aa90 31-b2d0-49ca-a379-0b08b7f6759b] X-ALT-DESC:The University of Basel and the French Embassy in Switzerland are organising a colloquium with panel discussion on the topic "More and more data: Opportunities and Risks in Health Care. Ethical\, social\, lega l and (educational) scientific perspectives."

\nThe event is bilingu al German-French with simultaneous translation.

\nFor more informati on see: https://www.unibas.ch/en/News-Events/Even ts.html?id=e2aa9031-b2d0-49ca-a379-0b08b7f6759b

\n\n DTEND;TZID=Europe/Zurich:20231106T200000 END:VEVENT BEGIN:VEVENT UID:news1573@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231014T174314 DTSTART;TZID=Europe/Zurich:20231030T121500 SUMMARY:Bernoullis Tafelrunde: Francesco Ballini (University of Oxford) DESCRIPTION:abstract [t3://file?uid=3510] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231030T130000 END:VEVENT BEGIN:VEVENT UID:news1583@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231024T091747 DTSTART;TZID=Europe/Zurich:20231027T110000 SUMMARY:Seminar in Numerical Analysis: Carsten Gräser (FAU Erlangen-Nürnb erg) DESCRIPTION:We consider the regularization of a supervised learning proble m by partial differential equations (PDEs). For the resulting regularized problem we derive error bounds in terms of a PDE error term and a data error term. These error contributions quantify the accuracy of the PDE mod el used for regularization and the data coverage. Furthermore\, the disc retization of the PDE-regularized learning problem by generalized Galerki n methods including finite elements and neural networks approaches is in vestigated. A nonlinear version of Céa's lemma allows to derive errors b ounds for both classes of discretizations and gives first insights into e rror analysis of variational neural network discretizations of PDEs.\\r\ \n\\r\\nFor further information about the seminar\, please visit this webp age [t3://page?uid=1115]. X-ALT-DESC:We consider the regularization of a supervised \;learning
problem by partial differential equations \;(PDEs). For the resulting
regularized problem we \;derive error bounds in terms of a PDE error
term \;and a data error term. These error contributions

quantify
the accuracy of the PDE model used for \;regularization and the data
coverage.

Furthermore\, the discretization of the PDE-regular
ized \;learning problem by generalized Galerkin methods \;includin
g finite elements and neural networks approaches \;is investigated. A
nonlinear version of Céa's lemma \;allows to derive errors bounds for
both classes of \;discretizations and gives first insights into error
\;analysis of variational neural network discretizations \;of PDE
s.

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20231027T120000 END:VEVENT BEGIN:VEVENT UID:news1572@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231010T131448 DTSTART;TZID=Europe/Zurich:20231023T121500 SUMMARY:Bernoullis Tafelrunde: Ana Marija Vego (ETH) DESCRIPTION:abstract [t3://file?uid=3502] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231023T130000 END:VEVENT BEGIN:VEVENT UID:news1590@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231016T120523 DTSTART;TZID=Europe/Zurich:20231020T151500 SUMMARY:Doktoratskolloquium Mathematik: Gerold Schefer DESCRIPTION:Ih's conjecture and logarithmic equidistribution X-ALT-DESC:Ih's conjecture and logarithmic equidistribution END:VEVENT BEGIN:VEVENT UID:news1537@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231013T095041 DTSTART;TZID=Europe/Zurich:20231020T110000 SUMMARY:Seminar in Numerical Analysis: Marco Zank (U Wien) DESCRIPTION:For the discretization of time-dependent partial differential e quations\, the standard approaches are explicit or implicit time-stepping schemes together with finite element methods in space. An alternative appr oach is the usage of space-time methods\, where the space-time domain is d iscretized and the resulting global linear system is solved at once. In th is talk\, some recent developments in space-time finite element methods ar e reviewed. For this purpose\, the heat equation and the wave equation ser ve as model problems. First\, for both model problems\, space-time variati onal formulations and their unique solvability in space-time Sobolev space s are discussed\, where a modified Hilbert transformation is used such tha t ansatz and test spaces are equal. Second\, conforming discretization sch emes\, using piecewise polynomial\, globally continuous functions\, are in troduced. Solvability and stability of these numerical schemes are discuss ed. Next\, we investigate efficient direct solvers for the occurring huge linear systems. The developed solvers are based on the Bartels--Stewart me thod and on the Fast Diagonalization method\, which result in solving a se quence of spatial subproblems. The solver based on the Fast Diagonalizatio n method allows solving these spatial subproblems in parallel\, leading to a full parallelization in time. In the last part of the talk\, numerical examples are shown and discussed.\\r\\n\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:For the discretization of time-dependent partial differential equations\, the standard approaches are explicit or implicit time-steppin g schemes together with finite element methods in space. An alternative ap proach is the usage of space-time methods\, where the space-time domain is discretized and the resulting global linear system is solved at once. In this talk\, some recent developments in space-time finite element methods are reviewed. For this purpose\, the heat equation and the wave equation s erve as model problems. First\, for both model problems\, space-time varia tional formulations and their unique solvability in space-time Sobolev spa ces are discussed\, where a modified Hilbert transformation is used such t hat ansatz and test spaces are equal. Second\, conforming discretization s chemes\, using piecewise polynomial\, globally continuous functions\, are introduced. Solvability and stability of these numerical schemes are discu ssed. Next\, we investigate efficient direct solvers for the occurring hug e linear systems. The developed solvers are based on the Bartels--Stewart method and on the Fast Diagonalization method\, which result in solving a sequence of spatial subproblems. The solver based on the Fast Diagonalizat ion method allows solving these spatial subproblems in parallel\, leading to a full parallelization in time. In the last part of the talk\, numerica l examples are shown and discussed.

\n\nFor further information abou t the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20231020T120000 END:VEVENT BEGIN:VEVENT UID:news1586@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231005T120839 DTSTART;TZID=Europe/Zurich:20231017T170000 SUMMARY:A slice of ... Diversity at the University of Basel (Diversity & In clusion team of the University of Basel) DESCRIPTION:The goal of these events is to invite experts\, and people affi liated with the department to give some input on gender equality and equit y here at the department and the university. As the title promises\, after the input you can ask burning questions and discuss while eating some fre sh slices of pizza!\\r\\nThe guest speakers of the first event are from th e Diversity & Inclusion team of the University of Basel. This event is aim ed at all staff and students of the DMI. See also the poster [t3://file?ui d=3498].\\r\\nWe would be very grateful if you could fill out the “doodl e” to let us know if you plan to join: https://xoyondo.com/dp/tzLuy4F5a BDv1Sx [https://xoyondo.com/dp/tzLuy4F5aBDv1Sx] X-ALT-DESC:The goal of these events is to invite experts\, and people af filiated with the department to give some input on gender equality and equ ity here at the department and the university. As the title promises\, aft er the input you can ask burning questions and discuss while eating some f resh slices of pizza!

\nThe guest speakers of the first event are fr om the Diversity &\; Inclusion team of the University of Basel. This ev ent is aimed at all staff and students of the DMI. See also the poster.

\nWe would be very grateful if you co uld fill out the “doodle” to let us know if you plan to join: \;https://xoyondo.com/dp/tzLu y4F5aBDv1Sx

END:VEVENT BEGIN:VEVENT UID:news1571@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231010T131421 DTSTART;TZID=Europe/Zurich:20231016T121500 SUMMARY:Bernoullis Tafelrunde: Henrik Wehrheim (University of Basel) DESCRIPTION:abstract [t3://file?uid=3501] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231016T130000 END:VEVENT BEGIN:VEVENT UID:news1562@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230926T153730 DTSTART;TZID=Europe/Zurich:20231013T110000 SUMMARY:Seminar in Numerical Analysis: Markus Weimar (Julius-Maximilians-Un iversität Würzburg) DESCRIPTION:As a rule of thumb in approximation theory\, the asymptotic spe ed of convergence of numerical algorithms is governed by the regularity of the objects we like to approximate. Besides classical isotropic Sobolev s moothness\, in the last decades the notion of so-called dominating- mixed regularity of functions turned out to be an important concept in numerical analysis. Indeed\, it naturally arises in high-dimensional real-world app lications\, e.g.\, related to the electronic Schrödinger equation. Althou gh optimal approximation rates for embeddings within the scales of isotr opic or dominating-mixed Lp-Sobolev spaces are well-understood\, not that much is known for embeddings across those scales (break-of-scale embedd ings).\\r\\nIn this lecture\, we first review the Fourier analytic approac h towards by now well-established (Besov and Triebel-Lizorkin) scales of d istribution spaces that measure either isotropic or dominating-mixed reg ularity. In addition\, we introduce new function spaces of hybrid smoothne ss which are able to simultaneously capture both types of regularity at the same time. As a further generalization of the aforementioned scales\, they particularly include standard Sobolev spaces on domains. On the other hand\, our new spaces yield an appropri- ate framework to study break-of- scale embeddings by means of harmonic analysis. We shall present (non-)ada ptive wavelet-based multiscale algorithms that approximate such embed- din gs at optimal dimension-independent rates of convergence. Important specia l cases cover the approximation of functions having dominating-mixed Sobol ev smoothness w.r.t. Lp in the norm of the (isotropic) energy space H1. \\r\\nThe talk is based on a recent paper [1] which represents the first p art of a joint work with Glenn Byrenheid (FSU Jena)\, Markus Hansen (PU Ma rburg)\, and Janina Hübner (RU Bochum).\\r\\nReferences:\\r\\n[1] G. Byre nheid\, J. Hübner\, and M. Weimar. Rate-optimal sparse approximation of c ompact break-of-scale embeddings. Appl. Comput. Harmon. Anal. 65:40–66\ , 2023 (arXiv:2203.10011).\\r\\nFor further information about the seminar\ , please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:As a rule of thumb in approximation theory\, the asymptotic s peed of convergence of numerical algorithms is governed by the regularity of the objects we like to approximate. Besides classical isotropic Sobolev smoothness\, in the last decades the notion of so-called dominating- mixe d regularity of functions turned out to be an important concept in numeric al analysis. Indeed\, it naturally arises in high-dimensional real-world a pplications\, e.g.\, related to the electronic Schrödinger equation. Alth ough optimal approximation rates for embeddings \;within \;the sca les of isotropic or dominating-mixed \;Lp-Sobolev spaces are well-unde rstood\, not that much is known for embeddings \;across \;those sc ales (break-of-scale embeddings).

\nIn this lecture\, we first revie w the Fourier analytic approach towards by now well-established (Besov and Triebel-Lizorkin) scales of distribution spaces that measure \;either \;isotropic or dominating-mixed regularity. In addition\, we introduc e new function spaces of hybrid smoothness which are able to \;simulta neously \;capture both types of regularity at the same time. As a furt her generalization of the aforementioned scales\, they particularly includ e standard Sobolev spaces on domains. On the other hand\, our new spaces y ield an appropri- ate framework to study break-of-scale embeddings by mean s of harmonic analysis. We shall present (non-)adaptive wavelet-based mult iscale algorithms that approximate such embed- dings at optimal dimension- independent rates of convergence. Important special cases cover the approx imation of functions having dominating-mixed Sobolev smoothness w.r.t.&nbs p\;Lp \;in the norm of the (isotropic) energy space \;H1.

\nThe talk is based on a recent paper [1] which represents the first part of a joint work with Glenn Byrenheid (FSU Jena)\, Markus Hansen (PU Marburg) \, and Janina Hübner (RU Bochum).

\nReferences:

\n[1] G. Byre nheid\, J. Hübner\, and M. Weimar. Rate-optimal sparse approximation of c ompact break-of-scale embeddings. Appl. Comput. Harmon. Anal. \;65:40 –66\, 2023 (arXiv:2203.10011).

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20231013T120000 END:VEVENT BEGIN:VEVENT UID:news1581@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20231005T110119 DTSTART;TZID=Europe/Zurich:20231012T161500 SUMMARY:PhD Defense Mathematics: Yannik Gleichmann DESCRIPTION:Adaptive Spectral Inversion for Inverse Medium Problems X-ALT-DESC:Adaptive Spectral Inversion for Inverse Medium Problems END:VEVENT BEGIN:VEVENT UID:news1561@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230925T172534 DTSTART;TZID=Europe/Zurich:20231009T121500 SUMMARY:Bernoullis Tafelrunde: Viacheslav Karnaev (University of Basel) DESCRIPTION:abstract [t3://file?uid=3497] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20231009T130000 END:VEVENT BEGIN:VEVENT UID:news1538@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230915T113109 DTSTART;TZID=Europe/Zurich:20230929T110000 SUMMARY:Seminar in Numerical Analysis: Rüdiger Kempf (U Bayreuth) DESCRIPTION:Reproducing kernel Hilbert spaces (RKHSs) and the closely rela ted kernel methods are well-established and well-studied tools in classi cal approximation theory. More recently\, they see many uses in other prob lems in applied and numerical analysis.\\r\\nIn machine learning\, support vector machines heavily rely on RKHSs. For neural networks Barron spaces are connected to certain RKHSs and offer a possibility for a theoretical a nalysis of these networks.\\r\\nAnother application of RKHSs is in high(er )-dimensional approximation. For instance in the field of quasi Monte-Carl o methods\, kernel-techniques are used to derive an error analysis for hig h-dimensional quadrature rules. We also developed a novel kernel-based app roximation method for higher-dimensional meshfree function reconstruction\ , based on Smolyak operators.\\r\\nIn this talk I will provide an introduc tion into the theory of RKHSs\, their kernels and associated kernel method s. In particular\, I will focus on a multiscale approximation scheme for r escaled radial basis functions. This method will then be used to derive th e new tensor product multilevel method for higher- dimensional meshfree approximation\, which I will discuss in detail.\\r\\n\\r\\nFor further inf ormation about the seminar\, please visit this webpage [t3://page?uid=1115 ]. X-ALT-DESC:Reproducing kernel Hilbert spaces (RKHSs) \;and the close ly related \;kernel methods \;are well-established and well-studie d tools in classical approximation theory. More recently\, they see many u ses in other problems in applied and numerical analysis.

\nIn machin e learning\, support vector machines heavily rely on RKHSs. For neural net works Barron spaces are connected to certain RKHSs and offer a possibility for a theoretical analysis of these networks.

\nAnother application of RKHSs is in high(er)-dimensional approximation. For instance in the fi eld of quasi Monte-Carlo methods\, kernel-techniques are used to derive an error analysis for high-dimensional quadrature rules. We also developed a novel kernel-based approximation method for higher-dimensional meshfree f unction reconstruction\, based on Smolyak operators.

\nIn this talk I will provide an introduction into the theory of RKHSs\, their kernels an d associated kernel methods. In particular\, I will focus on a multiscale approximation scheme for rescaled radial basis functions. This method will then be used to derive the new \;tensor product multilevel method&nbs p\;for higher- dimensional meshfree approximation\, which I will discuss i n detail.

\n\nFor further information about the seminar\, please vis it this webpage.

DTEND;TZID=Europe/Zurich:20230929T120000 END:VEVENT BEGIN:VEVENT UID:news1559@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230919T123033 DTSTART;TZID=Europe/Zurich:20230927T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Bian Wu (MPI Leipzig) DESCRIPTION:I will talk about Rayleigh-Taylor instability for two miscible\ , incompressible\, inviscid fluids. Scale-invariant estimates for the size of the mixing zone and coarsening of internal structures in the fully non linear regime are established. These bounds provide optimal scaling laws a nd reveal the strong role of dissipation in slowing down mixing. This is a joint work with Konstantin Kalinin\, Govind Menon. X-ALT-DESC:I will talk about Rayleigh-Taylor instability for two miscibl e\, incompressible\, inviscid fluids. Scale-invariant estimates for the si ze of the mixing zone and coarsening of internal structures in the fully n onlinear regime are established. These bounds provide optimal scaling laws and reveal the strong role of dissipation in slowing down mixing. This is a joint work with Konstantin Kalinin\, Govind Menon.

DTEND;TZID=Europe/Zurich:20230927T160000 END:VEVENT BEGIN:VEVENT UID:news1560@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230912T114142 DTSTART;TZID=Europe/Zurich:20230925T121500 SUMMARY:Bernoullis Tafelrunde: Jingeon An (University of Basel) DESCRIPTION:abstract [t3://file?uid=3479] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230925T130000 END:VEVENT BEGIN:VEVENT UID:news1536@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230904T192551 DTSTART;TZID=Europe/Zurich:20230922T110000 SUMMARY:Seminar in Numerical Analysis: Robert Gruhlke (FU Berlin) DESCRIPTION:Ensemble methods have become ubiquitous for solving Bayesian in ference problems\, in particular the efficient sampling from posterior den sities. State-of-the-art subclasses of Markow-Chain-Monte-Carlo methods r ely on gradient information of the log-density including Langevin samplers such as Ensemble Kalman Sampler (EKS) and Affine Invariant Langevin Dyna mics (ALDI). These dynamics are described by stochastic differential equa tions (SDEs) with time homogeneous drift terms. \\r\\nIn this talk we pre sent enhancement strategies of such ensemble methods based on sample enric hment and homotopy formalism\, that ultimately lead to time-dependent drif t terms that possible assimilate a larger class of target distributions w hile providing faster mixing times. \\r\\nFurthermore\, we present an alt ernative route to construct time-inhomogeneous drift terms based on rever se Diffusion processes that are popular in state-of-the-art Generative Mo delling such as Diffusion maps. Here\, we propose learning these log-dens ities by propagation of the target distribution through an Ornstein-Uhlenb eck process. For this\, we solve the associated Hamilton-Jabobi-Bellman eq uation through an adaptive explicit Euler discretization using low-rank co mpression such as functional Tensor Trains for the spatial discretization. \\r\\n\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Ensemble methods have become ubiquitous for solving Bayesian inference problems\, in particular the efficient sampling from posterior d ensities. \;State-of-the-art subclasses of Markow-Chain-Monte-Carlo me thods rely on gradient information of the log-density including Langevin s amplers such as \;Ensemble Kalman Sampler (EKS) and Affine Invariant L angevin Dynamics (ALDI). These dynamics are described by \;stochastic differential equations (SDEs) with time homogeneous drift terms. \;

\nIn this talk we present enhancement strategies of such ensemble meth ods based on sample enrichment and homotopy formalism\, that ultimately le ad to time-dependent drift terms that possible \;assimilate a larger c lass of target distributions while providing faster mixing times. \;\n

Furthermore\, we present an alternative route to construct \;ti me-inhomogeneous drift terms based on reverse Diffusion processes that are \;popular in state-of-the-art Generative Modelling such as Diffusion maps. \;Here\, we propose learning these log-densities by propagation of the target distribution through an Ornstein-Uhlenbeck process. For this \, we solve the associated Hamilton-Jabobi-Bellman equation through an ada ptive explicit Euler discretization using low-rank compression such as fun ctional Tensor Trains for the spatial discretization.

\n\nFor furthe r information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20230922T120000 END:VEVENT BEGIN:VEVENT UID:news1563@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230913T122018 DTSTART;TZID=Europe/Zurich:20230921T161500 SUMMARY:Habilitation lecture of PD Dr. Immanuel van Santen DESCRIPTION:After introducing the relevant notions\, we will consider the c lassical setting of algebraic embeddings into Euclidean space.\\r\\nTherea fter\, we will focus on more general targets for algebraic embeddings\, ma inly linear algebraic groups. X-ALT-DESC:After introducing the relevant notions\, we will consider the classical setting of algebraic embeddings into Euclidean space.

\nT hereafter\, we will focus on more general targets for algebraic embeddings \, mainly linear algebraic groups.

\n\n END:VEVENT BEGIN:VEVENT UID:news1547@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230904T075228 DTSTART;TZID=Europe/Zurich:20230920T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Chiara Boccato (Universi ty of Milano) DESCRIPTION:The interacting Bose gas is a system in quantum statistical mec hanics where a collective behavior emerges from the underlying many-body t heory\, posing interesting challenges to its rigorous mathematical descrip tion.\\r\\nWhile at temperature close to zero we have precise information on the ground state energy and the low-lying spectrum of excitations (at l east in certain scaling limits)\, much less is known close to the critical point. In this talk I will discuss how thermal excitations can be describ ed by Bogoliubov theory\, allowing us to estimate the free energy of the B ose gas in the Gross-Pitaevskii regime.\\r\\n\\r\\nThis is joint work with A. Deuchert and D. Stocker. X-ALT-DESC:The interacting Bose gas is a system in quantum statistical m echanics where a collective behavior emerges from the underlying many-body theory\, posing interesting challenges to its rigorous mathematical descr iption.

\nWhile at temperature close to zero we have precise informa tion on the ground state energy and the low-lying spectrum of excitations (at least in certain scaling limits)\, much less is known close to the cri tical point. In this talk I will discuss how thermal excitations can be de scribed by Bogoliubov theory\, allowing us to estimate the free energy of the Bose gas in the Gross-Pitaevskii regime.

\n\nThis is joint work with A. Deuchert and D. Stocker.

DTEND;TZID=Europe/Zurich:20230920T153000 END:VEVENT BEGIN:VEVENT UID:news1552@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230816T153440 DTSTART;TZID=Europe/Zurich:20230905T161500 SUMMARY:[Talk in German] Creativity and critical thinking in computer scien ce lessons DESCRIPTION:The talk will be held in German.\\r\\nInformatikunterricht hat nichts damit zu tun\, aus «Schülerinnen und Schülern Computer zu machen » — für die Förderung vieler zentraler Informatikkompetenzen werden C omputer nicht einmal gebraucht. Ansprechender und sinnstiftender Informati kunterricht ist das Gegenteil davon: Er stellt kreatives Problemlösen ins Zentrum und ist gleichermassen spielerisch wie herausfordernd. In diesem Vortrag möchte ich Beispiele aufzeigen\, wie Grundkonzepte der Informatik im Unterricht thematisiert werden können\, die kritisches Denken sowie K reativität fördern.\\r\\nDennis Komm studierte Informatik und Psychologi e an der RWTH Aachen sowie Informationstechnologie an der QUT Brisbane. Er promovierte 2012 an der ETH Zürich und arbeitete nach seiner Postdoc-Zei t an der ETH Zürich und anderen Hochschulen als Dozent und Senior Scienti st. Ab 2021 war er Professor für Fachdidaktik Informatik an der PH Graub ünden. Seit 2022 ist er ausserordentlicher Professor an der ETH Zürich f ür Algorithmen und Didaktik sowie Lehrgangsleiter des CAS Informatik und Informatikdidaktik für Lehrpersonen der Primar- und Sekundarstufe. Seine Forschungsinteressen sind der Entwurf und die Analyse von Algorithmen sowi e die Informatikausbildung\, speziell die Vermittlung von grundlegenden Id een und Konzepten der Informatik. X-ALT-DESC:The talk will be held in German.

\nInformatikunterricht hat nichts damit zu tun\, aus «Schülerinnen und Schülern Computer zu m achen» — für die Förderung vieler zentraler Informatikkompetenzen wer den Computer nicht einmal gebraucht. Ansprechender und sinnstiftender Info rmatikunterricht ist das Gegenteil davon: Er stellt kreatives Problemlöse n ins Zentrum und ist gleichermassen spielerisch wie herausfordernd. In di esem Vortrag möchte ich Beispiele aufzeigen\, wie Grundkonzepte der Infor matik im Unterricht thematisiert werden können\, die kritisches Denken so wie Kreativität fördern.

\nDennis Komm studierte Informatik und Ps ychologie an der RWTH Aachen sowie Informationstechnologie an der QUT Bris bane. Er promovierte 2012 an der ETH Zürich und arbeitete nach seiner Pos tdoc-Zeit an der ETH Zürich und anderen Hochschulen als Dozent und Senior Scientist. Ab 2021 war er Professor für Fachdidaktik Informatik an der P H Graubünden. Seit 2022 ist er ausserordentlicher Professor an der ETH Z ürich für Algorithmen und Didaktik sowie Lehrgangsleiter des CAS Informa tik und Informatikdidaktik für Lehrpersonen der Primar- und Sekundarstufe . Seine Forschungsinteressen sind der Entwurf und die Analyse von Algorith men sowie die Informatikausbildung\, speziell die Vermittlung von grundleg enden Ideen und Konzepten der Informatik.

END:VEVENT BEGIN:VEVENT UID:news1539@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230619T111413 DTSTART;TZID=Europe/Zurich:20230628T180000 SUMMARY:[in German] Uni konkret – Wissenschaft erleben DESCRIPTION:Der Anlass ist für Sie kostenlos.\\r\\nDie Teilnehmerzahl ist begrenzt. Anmeldungen werden in der Reihenfolge des Eingangs berücksichti gt.\\r\\nHier [https://join.events.unibas.ch/event.php?vnrtoken=JChTkEKIw8 xcNGLcGEmKpjXJrWEIpm8PZ38eG+DP4RjBTEjUAzIMP/1TntAt/fPBFV3Q4Tzd1+wdXqmhwg67 Ns4=] können Sie sich anmelden.\\r\\nBig Data\, Machine Learning und kün stliche Intelligenz gehören zu den Schwerpunkten von Professor Heiko Schu ldt\, vom Departement für Mathematik und Informatik der Universität Base l. Seine Forschungsgruppe entwickelt derzeit eine Multimedia-Suchmaschine\ , mit der man grosse Mengen an Bildern\, Videos und 3d-Modellen mit neuart igen Methoden durchsuchen kann. Gemeinsam mit der Basler Firma 4eyes arbei ten die Wissenschaftlerinnen und Wissenschaftler an einer einer Anwendung\ , mit der multimediale Objekte in Museen und Archiven erschlossen werden k önnen. In einem anderen Projekt forscht das Team an einem neuartigen Date nbanksystem\, mit dem Daten in komplett unterschiedlichen Formaten zusamme n gespeichert und abgefragt werden können. Dieses Datenbanksystem wird de rzeit mit einem Start-up unter dem Markennamen «Polypheny» kommerzialisi ert. Am Mittwoch\, 28. Juni\, bieten Heiko Schuldt und sein Team einen Ein blick in ihre Arbeit. Erfahren Sie\, wie die Erkenntnisse der Grundlagenfo rschung rasch in konkrete Projekte überführt werden und so Mehrwert für unsere Region geschaffen wird. Werfen Sie im Rahmen von «Uni konkret» e inen Blick in die Labors und diskutieren Sie mit den Forschenden. Im Video erfahren Sie mehr zum aktuellen Anlass.\\r\\nProgramm\\r\\nBegrüssung Re ferate Q & A Apéro Ende der Veranstaltung X-ALT-DESC:Der Anlass ist für Sie kostenlos.

\nDie Teilnehmerzahl ist begrenzt. Anmeldungen werden in der Reihenfolge des Eingangs berücks ichtigt.

\n**Hier** können Sie sich anmelden.

Big Data\, Machine Learning und künstliche Intelligenz gehören zu de
n Schwerpunkten von Professor Heiko Schuldt\, vom Departement für Mathema
tik und Informatik der Universität Basel. Seine Forschungsgruppe entwicke
lt derzeit eine Multimedia-Suchmaschine\, mit der man grosse Mengen an Bil
dern\, Videos und 3d-Modellen mit neuartigen Methoden durchsuchen kann. Ge
meinsam mit der Basler Firma 4eyes arbeiten die Wissenschaftlerinnen und W
issenschaftler an einer einer Anwendung\, mit der multimediale Objekte in
Museen und Archiven erschlossen werden können.

In einem anderen Pro
jekt forscht das Team an einem neuartigen Datenbanksystem\, mit dem Daten
in komplett unterschiedlichen Formaten zusammen gespeichert und abgefragt
werden können. Dieses Datenbanksystem wird derzeit mit einem Start-up unt
er dem Markennamen «Polypheny» kommerzialisiert.

Am Mittwoch\, 28.
Juni\, bieten Heiko Schuldt und sein Team einen Einblick in ihre Arbeit.
Erfahren Sie\, wie die Erkenntnisse der Grundlagenforschung rasch in konkr
ete Projekte überführt werden und so Mehrwert für unsere Region geschaf
fen wird.

Werfen Sie im Rahmen von «Uni konkret» einen Blick in di
e Labors und diskutieren Sie mit den Forschenden. Im Video erfahren Sie me
hr zum aktuellen Anlass.

__Programm__

Begrüssung

Referate

Q &\; A

Apéro

Ende der Veranstaltung

Der Anlass ist für Sie kostenlos.

\nDie Teilnehmerzahl ist begrenzt. Anmeldungen werden in der Reihenfolge des Eingangs berücks ichtigt.

\n**Hier** können Sie sich
anmelden.

Big Data\, Machine Learning und künstliche Intelligenz
gehören zu den Schwerpunkten von Professor Heiko Schuldt\, vom Departemen
t für Mathematik und Informatik der Universität Basel. Seine Forschungsg
ruppe entwickelt derzeit eine Multimedia-Suchmaschine\, mit der man grosse
Mengen an Bildern\, Videos und 3d-Modellen mit neuartigen Methoden durchs
uchen kann. Gemeinsam mit der Basler Firma 4eyes arbeiten die Wissenschaft
lerinnen und Wissenschaftler an einer einer Anwendung\, mit der multimedia
le Objekte in Museen und Archiven erschlossen werden können.

In ein
em anderen Projekt forscht das Team an einem neuartigen Datenbanksystem\,
mit dem Daten in komplett unterschiedlichen Formaten zusammen gespeichert
und abgefragt werden können. Dieses Datenbanksystem wird derzeit mit eine
m Start-up unter dem Markennamen «Polypheny» kommerzialisiert.

Am
Montag\, 12. Juni\, bieten Heiko Schuldt und sein Team einen Einblick in i
hre Arbeit. Erfahren Sie\, wie die Erkenntnisse der Grundlagenforschung ra
sch in konkrete Projekte überführt werden und so Mehrwert für unsere Re
gion geschaffen wird.

Werfen Sie im Rahmen von «Uni konkret» einen
Blick in die Labors und diskutieren Sie mit den Forschenden. Im Video erf
ahren Sie mehr zum aktuellen Anlass.

__Programm__

Begr
üssung

Referate

Q &\; A

Apéro

Ende der Verans
taltung

The Surface quasi-geostrophic (SQG) equation is an important active scalar model\, both due to its shared properties with 3D Euler as w ell as for its applications to model certain atmospherical phenomena. It h as already been established that instantaneous loss of regularity can occu r in the inviscid case in certain Sobolev spaces\, but it is unclear at wh at point the diffusion prevents this phenomenon from happening. In this ta lk I will discuss the behaviour when there is some super-critical fraction al diffusion.

DTEND;TZID=Europe/Zurich:20230607T160000 END:VEVENT BEGIN:VEVENT UID:news1533@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230524T113428 DTSTART;TZID=Europe/Zurich:20230605T170000 SUMMARY:ChatGPT Demystified: Insights into Development\, Ethics & Sustainab ility\, and Real-World Use Cases DESCRIPTION:Speaker:\\r\\nFatos Ismali\, Microsoft AI\\r\\nAbstract:\\r\\n “This session will provide an overview of the GPT-family of models\, the ir architecture\, training processes\, various technical consideration to consider when deploying them for different business scenarios. It will als o address the ethical challenges associated with AI-driven language models \, including potential biases\, content moderation\, and data privacy and security. Lastly\, the talk will explore the diverse use cases of GPT\, hi ghlighting its transformative impact on industries such as media\, healthc are\, customer service\, and content creation. Join us as we unravel the i ntricacies of ChatGPT and discuss its potential to revolutionize human-AI interaction.”\\r\\nCurriculum Vitae:\\r\\nFatos Ismali is a Senior Data & AI Solutions Architect at Microsoft UK\, where he passionately utilizes advanced AI and ML technologies to tackle business and societal challenges . Before joining Microsoft\, he worked as a Cloud Architect at Oracle. In his current role\, Fatos leads the Conversational AI and Cognitive Service s task force\, focusing on helping large enterprises widely adopt AI and M L. He offers guidance to C-level executives\, Chief Data Officers\, and Da ta and AI Architects on achieving AI maturity\, creating cross-functional Data Science teams\, and developing AI capabilities within Microsoft's Azu re Cloud. Fatos has partnered with leading global organizations across var ious industries\, including Financial Services\, Insurance\, Public Sector \, Media and Telecommunications\, and Manufacturing. In March 2020\, he re ceived Microsoft's Champions Award for his significant contributions to th e UK's NHS by developing the data analytics platform for the NHSX COVID-19 Test and Trace program. In April 2023\, Fatos earned his second Champions Award for his pivotal work in establishing patterns for Large Language Mo dels adoption within the telecommunications industry using Azure Open AI. With a keen interest in Natural Language Processing (NLP) and Machine Lear ning Operationalization (MLOps)\, Fatos contributed to a major UK manufact uring organization's MLOps architecture\, which won the DevOps Industry Aw ard in 2021. Outside of Microsoft\, Fatos founded and manages the Data Sci ence Initiative meetup community in London\, consisting of over 3\,600 Dat a Scientists. This community encourages collaboration and knowledge sharin g through presentations\, workshops\, and hackathons. As an international speaker\, Fatos often presents on topics like MLOps\, NLP\, Cognitive AI\, and ML. He holds a BSc in Computer Science and a Master's degree in Data Warehouses and Business Intelligence. X-ALT-DESC:__Speaker:__

Fatos Ismali\, Microsoft AI

\n< u>Abstract:

\n“This session will provide an overview of the GP T-family of models\, their architecture\, training processes\, various tec hnical consideration to consider when deploying them for different busines s scenarios. It will also address the ethical challenges associated with A I-driven language models\, including potential biases\, content moderation \, and data privacy and security. Lastly\, the talk will explore the diver se use cases of GPT\, highlighting its transformative impact on industries such as media\, healthcare\, customer service\, and content creation. Joi n us as we unravel the intricacies of ChatGPT and discuss its potential to revolutionize human-AI interaction.”

\n__Curriculum Vitae:__\n

Fatos Ismali is a Senior Data &\; AI Solutions Architect at Micr
osoft UK\, where he passionately utilizes advanced AI and ML technologies
to tackle business and societal challenges. Before joining Microsoft\, he
worked as a Cloud Architect at Oracle. In his current role\, Fatos leads t
he Conversational AI and Cognitive Services task force\, focusing on helpi
ng large enterprises widely adopt AI and ML. He offers guidance to C-level
executives\, Chief Data Officers\, and Data and AI Architects on achievin
g AI maturity\, creating cross-functional Data Science teams\, and develop
ing AI capabilities within Microsoft's Azure Cloud.

Fatos has partne
red with leading global organizations across various industries\, includin
g Financial Services\, Insurance\, Public Sector\, Media and Telecommunica
tions\, and Manufacturing. In March 2020\, he received Microsoft's Champio
ns Award for his significant contributions to the UK's NHS by developing t
he data analytics platform for the NHSX COVID-19 Test and Trace program. I
n April 2023\, Fatos earned his second Champions Award for his pivotal wor
k in establishing patterns for Large Language Models adoption within the t
elecommunications industry using Azure Open AI.

With a keen interest
in Natural Language Processing (NLP) and Machine Learning Operationalizat
ion (MLOps)\, Fatos contributed to a major UK manufacturing organization's
MLOps architecture\, which won the DevOps Industry Award in 2021.

O
utside of Microsoft\, Fatos founded and manages the Data Science Initiativ
e meetup community in London\, consisting of over 3\,600 Data Scientists.
This community encourages collaboration and knowledge sharing through pres
entations\, workshops\, and hackathons. As an international speaker\, Fato
s often presents on topics like MLOps\, NLP\, Cognitive AI\, and ML. He ho
lds a BSc in Computer Science and a Master's degree in Data Warehouses and
Business Intelligence.

The advection-diffusion equation is known to have unique solu
tions for any vector field that is L^2 in time and in space. But what happ
ens when we have slightly less than square integrability? In this talk we
will explore two examples of vector fields in L^p(0\,T\;L^q(\\T^d)) made o
f shear flows that prove the non-uniqueness of solutions whenever we have
p<\;2 or q<\;2. We will first show that they give different solutions
to the advection equation and then use the Feynman-Kac formula to show tha
t diffusion has little effect if our parameters are well-tuned.

This
is part of my Master's thesis\, supervised by Massimo Sorella and Maria C
olombo.

The phenomenon of anomalous dissipation in turbulence predict s the existence of solutions to the incompressible Euler equations that en joy regularity consistent with Kolmogorov’s 4/5 law and satisfy a local energy inequality. The "strong Onsager conjecture" asserts that such solut ions do indeed exist. In this talk\, we will discuss the background and mo tivation behind the strong Onsager conjecture. \; In addition\, we out line a construction of solutions with regularity (nearly) consistent with the 4/5 law\, thereby proving the conjecture in the natural L^3 scale of B esov spaces. \; This is based on joint work with Hyunju Kwon and Vikra m Giri.

DTEND;TZID=Europe/Zurich:20230517T160000 END:VEVENT BEGIN:VEVENT UID:news1499@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230503T142939 DTSTART;TZID=Europe/Zurich:20230517T121500 SUMMARY:Bernoullis Tafelrunde: Elena Sammarco (Roma Tre University) DESCRIPTION:abstract [t3://file?uid=3367] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230517T130000 END:VEVENT BEGIN:VEVENT UID:news1464@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230509T105935 DTSTART;TZID=Europe/Zurich:20230512T110000 SUMMARY:Seminar in Numerical Analysis: Martin Eigel (WIAS Berlin) DESCRIPTION:Weighted least squares methods have been examined thouroughly t o obtain quasi-optimal convergence results for a chosen (polynomial) basis of a linear space. A focus in the analysis lies on the construction of op timal sampling measures and the derivation of a sufficient sample complexi ty for stable reconstructions. When considering holomorphic functions such as solutions of common parametric PDEs\, the anisotropic sparsity they ex hibit can be exploited to achieve improved results adapted to the consider ed problem. In particular\, the sparsity of the data transfers to the solu tion sparsity in terms of polynomial chaos coefficients. When using nonlin ear model classes\, it turns out that the known results cannot be used dir ectly. To obtain comparable a priori rates\, we introduce a new weighted v ersion of Stechkin's lemma. This enables to obtain optimal complexity resu lts for a model class of low-rank tensor trains. We also show that the sol ution sparsity results in sparse component tensors and sketch how this can be realised in practical algorithms. A nice application is the reconstruc tion of Galerkin solutions for parametric PDEs. With this\, a provably con verging a posteriori adaptive algorithm can be derived for linear model PD Es with non-affine coefficients.\\r\\n\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Weighted least squares methods have been examined thouroughly to obtain quasi-optimal convergence results for a chosen (polynomial) bas is of a linear space. A focus in the analysis lies on the construction of optimal sampling measures and the derivation of a sufficient sample comple xity for stable reconstructions. When considering holomorphic functions su ch as solutions of common parametric PDEs\, the anisotropic sparsity they exhibit can be exploited to achieve improved results adapted to the consid ered problem. In particular\, the sparsity of the data transfers to the so lution sparsity in terms of polynomial chaos coefficients. When using nonl inear model classes\, it turns out that the known results cannot be used d irectly. To obtain comparable a priori rates\, we introduce a new weighted version of Stechkin's lemma. This enables to obtain optimal complexity re sults for a model class of low-rank tensor trains. We also show that the s olution sparsity results in sparse component tensors and sketch how this c an be realised in practical algorithms. A nice application is the reconstr uction of Galerkin solutions for parametric PDEs. With this\, a provably c onverging a posteriori adaptive algorithm can be derived for linear model PDEs with non-affine coefficients.

\n\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20230512T120000 END:VEVENT BEGIN:VEVENT UID:news1462@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230417T113022 DTSTART;TZID=Europe/Zurich:20230511T161500 SUMMARY:Public inaugural lecture of Prof. Dr. Isabel Wagner DESCRIPTION:The Department of Mathematics and Computer Science kindly invit es you to the inaugural lecture of Prof. Dr. Isabel Wagner ein.\\r\\nAfter the lecture an apéro will be offered. X-ALT-DESC:The Department of Mathematics and Computer Science kindly inv ites you to the inaugural lecture of Prof. Dr. Isabel Wagner ein.

\nAfter the lecture an apéro will be offered.

DTEND;TZID=Europe/Zurich:20230511T171500 END:VEVENT BEGIN:VEVENT UID:news1509@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230503T093616 DTSTART;TZID=Europe/Zurich:20230508T121500 SUMMARY:Bernoullis Tafelrunde: Carl Johansson (EPFL) DESCRIPTION:abstract [t3://file?uid=3366] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230508T130000 END:VEVENT BEGIN:VEVENT UID:news1506@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20240417T154543 DTSTART;TZID=Europe/Zurich:20230505T172000 SUMMARY:BZ Seminar in Analysis: Serena Cenatiempo (GSSI L'Aquila) DESCRIPTION:In the last decades\, since the first experimental realizations of Bose-Einstein condensates\, the study of large bosonic systems has bee n a very active field of research both in physics and in mathematics. In t his talk we address a question strictly related to condensation\, namely t he characterization of macroscopic observables. More precisely\, we consid er dilute Bose gases and we focus on the second order asymptotic expansion for the ground state energy\, which is believed to exhibit a universal be haviour\, independent on the detail of the interaction. We present a new u pper bound for a dilute gas of hard core bosons in the thermodynamic limit \, where the number of particles and the size of the box are sent to infin ity while keeping the density fixed. Our result resolves the ground state energy up to an error of the order of the sub-leading correction. We also discuss the Gross-Pitaevskii regime\, in which N hard spheres with radius of order 1/N move on the unit torus\; in this setting\, we show an upper b ound for the energy\, capturing the correct second order correction. Based on joint works with G. Basti\, A. Giuliani\, A. Olgiati\, G. Pasqualetti\ , B. Schlein. X-ALT-DESC:In the last decades\, since the first experimental realizatio
ns of Bose-Einstein condensates\, the study of large bosonic systems has b
een a very active field of research both in physics and in mathematics. In
this talk we address a question strictly related to condensation\, namely
the characterization of macroscopic observables. More precisely\, we cons
ider dilute Bose gases and we focus on the second order asymptotic expansi
on for the ground state energy\, which is believed to exhibit a universal
behaviour\, independent on the detail of the interaction.

We present
a new upper bound for a dilute gas of hard core bosons in the thermodynam
ic limit\, where the number of particles and the size of the box are sent
to infinity while keeping the density fixed. Our result resolves the groun
d state energy up to an error of the order of the sub-leading correction.
We also discuss the Gross-Pitaevskii regime\, in which N hard spheres with
radius of order 1/N move on the unit torus\; in this setting\, we show an
upper bound for the energy\, capturing the correct second order correctio
n.

Based on joint works with G. Basti\, A. Giuliani\, A. Olgiati\, G
. Pasqualetti\, B. Schlein.

Given a 2-dimensional closed surface\, we will show that the Moser-Trudinger functional has critical points of arbitrarily high energy. Since the functional is too critical to directly apply to it the known va riational methods (in particular the Struwe monotonicity trick)\, we will approximate it by subcritical ones\, which in fact interpolate it to a Lio uville-type functional from conformal geometry. Hence our result will also unify and give common results for these two apparently unrelated problems . This is a joint work with F. De Marchis\, A. Malchiodi and P-D. Thizy. DTEND;TZID=Europe/Zurich:20230505T170000 END:VEVENT BEGIN:VEVENT UID:news1510@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230425T131110 DTSTART;TZID=Europe/Zurich:20230505T153000 SUMMARY:Dr. Iain McGilchrist: The hemisphere lateralization hypothesis and our approach to basic research DESCRIPTION:The Center for Data Analytics (CeDA) is proud to present the fi rst speaker in its new colloquium series:\\r\\nDr. Iain McGilchrist is a p sychiatrist\, neuroscientist\, and philosopher best known for his books “The Master and His Emissary” and “The Matter With Things”. In the se works\, he compiles a wide body of research from science\, philosophy a nd history\, demonstrating that the two hemispheres of our brain have fund amentally different ways of attending to the world. He discusses the impac t of this tension on our cultural evolution\, as well as how it relates to epistemology and metaphysics. In this colloquium\, Dr. McGilchrist will d iscuss the implications of his lateralization hypothesis on our approach t o basic research\, particularly in the life sciences. This will be followe d by a round table discussion with Professor Cristina Granziera of the Dep artment of Biomedical Engineering\, and Professor Philipp Sterzer at the P sychiatric Hospital UPK.\\r\\nDr. McGilchrist will also be speaking in Gen eva on May 8th at IdeaSquare (CERN) and May 9th at The Fab (the Graduate I nstitute). X-ALT-DESC:

The Center for Data Analytics (CeDA) is proud to present the first speaker in its new colloquium series:

\nDr. Iain McGilchrist i s a psychiatrist\, neuroscientist\, and philosopher best known for his boo ks “The Master and His Emissary” and “The Matter With Things”. In these works\, he compiles a wide body of research from science\, philosoph y and history\, demonstrating that the two hemispheres of our brain have f undamentally different ways of attending to the world. He discusses the im pact of this tension on our cultural evolution\, as well as how it relates to epistemology and metaphysics. In this colloquium\, Dr. McGilchrist wil l discuss the implications of his lateralization hypothesis on our approac h to basic research\, particularly in the life sciences. This will be foll owed by a round table discussion with Professor Cristina Granziera of the Department of Biomedical Engineering\, and Professor Philipp Sterzer at th e Psychiatric Hospital UPK.

\nDr. McGilchrist will also be speaking in Geneva on May 8th at IdeaSquare (CERN) and May 9th at The Fab (the Grad uate Institute).

END:VEVENT BEGIN:VEVENT UID:news1500@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230427T100910 DTSTART;TZID=Europe/Zurich:20230505T110000 SUMMARY:Seminar in Numerical Analysis: Elena Moral Sánchez (Max-Planck Ins titute for Plasma Physics) DESCRIPTION:The cold-plasma wave equation describes the propagation of an e lectromagnetic wave in a magnetized plasma\, which is an inhomogeneous\, d ispersive and anisotropic medium. The thermal effects are assumed to be ne gligible\, which leads to a linear partial differential equation. Besides\ , we assume that the electromagnetic field of the propagating wave is in t he time-harmonic regime. This model has applications in magnetic confineme nt fusion devices\, like the Tokamak. Namely\, electromagnetic waves are u sed to heat up the plasma (Electron cyclotron resonance heating (ECRH)) or for interferometry and reflectometry diagnostics (to measure plasma densi ty and position\, etc.). In the first part of this talk\, we introduce th e cold-plasma model\, together with a qualitative study of the plasma mode s which expose the complexity of the problem. In the second part\, we desc ribe the problem and the simplifications we carry out\, which yield the in definite Helmholtz equation. It is solved with B-Spline Finite Elements pr ovided by the Psydac library and some results are shown. Lastly\, we discu ss the performance and potential ways of preconditioning.\\r\\n\\r\\nFor f urther information about the seminar\, please visit this webpage [t3://pag e?uid=1115]. X-ALT-DESC:The cold-plasma wave equation describes the propagation of an
electromagnetic wave in a magnetized plasma\, which is an inhomogeneous\,
dispersive and anisotropic medium. The thermal effects are assumed to be
negligible\, which leads to a linear partial differential equation. Beside
s\, we assume that the electromagnetic field of the propagating wave is in
the time-harmonic regime.

This model has applications in magnetic c
onfinement fusion devices\, like the Tokamak. Namely\, electromagnetic wav
es are used to heat up the plasma (Electron cyclotron resonance heating (E
CRH)) or for interferometry and reflectometry diagnostics (to measure plas
ma density and position\, etc.).

In the first part of this ta
lk\, we introduce the cold-plasma model\, together with a qualitative stud
y of the plasma modes which expose the complexity of the problem.

In
the second part\, we describe the problem and the simplifications we carr
y out\, which yield the indefinite Helmholtz equation. It is solved with B
-Spline Finite Elements provided by the Psydac library and some results ar
e shown. Lastly\, we discuss the performance and potential ways of precond
itioning.

For further information about the seminar\, please vis it this webpage.

DTEND;TZID=Europe/Zurich:20230505T120000 END:VEVENT BEGIN:VEVENT UID:news1471@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230209T095509 DTSTART;TZID=Europe/Zurich:20230504T170000 SUMMARY:Bernoulli Meets Industry: Christian Schulze (Baloise) DESCRIPTION:Apero afterwards! [t3://page?uid=239]poster [t3://file?uid=331 6] X-ALT-DESC:Apero afterwards!poster

DTEND;TZID=Europe/Zurich:20230504T183000 END:VEVENT BEGIN:VEVENT UID:news1472@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230417T092542 DTSTART;TZID=Europe/Zurich:20230428T110000 SUMMARY:Seminar in Numerical Analysis: Frédéric Nataf (CNRS — Universit é Pierre et Marie Curie) DESCRIPTION:We introduce a scalable adaptive element-based domain decomposi tion (DD) method for solving saddle point problems defined as a block two by two matrix. The algorithm does not require any knowledge of the constra ined space. We assume that all sub matrices are sparse and that the diagon al blocks are spectrally equivalent to a sum of positive semi definite mat rices. The latter assumption enables the design of adaptive coarse space f or DD methods that extends the GenEO theory to saddle point problems. Nume rical results on three dimensional elasticity problems for steel-rubber st ructures discretized by a finite element with continuous pressure are show n for up to one billion degrees of freedom along with comparisons to Algeb raic Multigrid Methods.\\r\\n\\r\\nFor further information about the semin ar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:We introduce a scalable adaptive element-based domain decompo sition (DD) method for solving saddle point problems defined as a block tw o by two matrix. The algorithm does not require any knowledge of the const rained space. We assume that all sub matrices are sparse and that the diag onal blocks are spectrally equivalent to a sum of positive semi definite m atrices. The latter assumption enables the design of adaptive coarse space for DD methods that extends the GenEO theory to saddle point problems. Nu merical results on three dimensional elasticity problems for steel-rubber structures discretized by a finite element with continuous pressure are sh own for up to one billion degrees of freedom along with comparisons to Alg ebraic Multigrid Methods.

\n\nFor further information about the semi nar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20230428T120000 END:VEVENT BEGIN:VEVENT UID:news1457@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230309T105739 DTSTART;TZID=Europe/Zurich:20230427T161500 SUMMARY:Perlen-Colloquium: Dr. Frank Bretz (Novartis) DESCRIPTION:We consider the problem of testing multiple null hypotheses\, w here a decision to reject or retain must be made for each one and embeddin g incorrect decisions into a real-life context may inflict different losse s. We argue that traditional methods controlling the Type I error rate may be too restrictive in this situation and that the standard familywise err or rate may not be appropriate. Using a decision-theoretic approach\, we d efine suitable loss functions for a given decision rule\, where incorrect decisions can be treated unequally by assigning different loss values. Tak ing expectation with respect to the sampling distribution of the data allo ws us to control the familywise expected loss instead of the conventional familywise error rate. Different loss functions can be adopted\, and we se arch for decision rules that satisfy certain optimality criteria within a broad class of decision rules for which the expected loss is bounded by a fixed threshold under any parameter configuration. We illustrate the metho ds with the problem of establishing efficacy of a new medicinal treatment in non-overlapping subgroups of patients. X-ALT-DESC:We consider the problem of testing multiple null hypotheses\, where a decision to reject or retain must be made for each one and embedd ing incorrect decisions into a real-life context may inflict different los ses. We argue that traditional methods controlling the Type I error rate m ay be too restrictive in this situation and that the standard familywise e rror rate may not be appropriate. Using a decision-theoretic approach\, we define suitable loss functions for a given decision rule\, where incorrec t decisions can be treated unequally by assigning different loss values. T aking expectation with respect to the sampling distribution of the data al lows us to control the familywise expected loss instead of the conventiona l familywise error rate. Different loss functions can be adopted\, and we search for decision rules that satisfy certain optimality criteria within a broad class of decision rules for which the expected loss is bounded by a fixed threshold under any parameter configuration. We illustrate the met hods with the problem of establishing efficacy of a new medicinal treatmen t in non-overlapping subgroups of patients.

END:VEVENT BEGIN:VEVENT UID:news1483@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230418T150401 DTSTART;TZID=Europe/Zurich:20230426T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Ángel Castro (ICMAT\, M adrid) DESCRIPTION:In this talk we will consider the existence of traveling waves arbitrarily close to shear flows for the 2D incompressible Euler equat ions. In particular we shall present some results concerning the existence of such solutions near the Couette\, Taylor-Couette and the Poiseuille f lows. In the first part of the talk we will introduce the problem and revi ew some well known results on this topic. In the second one some of the ideas behind the construction of our traveling waves will be sketched. X-ALT-DESC:In this talk we will consider the existence of traveling wave s arbitrarily close to \; shear flows for \; the 2D incompressible Euler equations. In particular we shall present some results concerning t he existence of such solutions near the Couette\, Taylor-Couette and the P oiseuille \;flows. In the first part of the talk we will introduce the problem and review some well known results on this topic. In the \; s econd one some of the ideas behind the construction of our traveling waves \; will be sketched.

DTEND;TZID=Europe/Zurich:20230426T160000 END:VEVENT BEGIN:VEVENT UID:news1498@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230403T110850 DTSTART;TZID=Europe/Zurich:20230424T121500 SUMMARY:Bernoullis Tafelrunde: Stefano Abbate (GSSI - Gran Sasso Science In stitute) DESCRIPTION:abstract [t3://file?uid=3352] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230424T130000 END:VEVENT BEGIN:VEVENT UID:news1480@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230418T090618 DTSTART;TZID=Europe/Zurich:20230421T110000 SUMMARY:Seminar in Numerical Analysis: Omar Lakkis (University of Sussex) DESCRIPTION:Least-squares finite element recovery-based methods provide a s imple and practical way to approximate linear elliptic PDEs in nondivergen ce form where standard variational approach either fails or requires techn ically complex modifications.\\r\\nThis idea allows the creation of effici ent solvers for fully nonlinear elliptic equations\, the linearization of which leaves us with an equation in nondivergence form. An important class of fully nonlinear elliptic PDEs can be written in Hamilton--Jacobi--Bell man (Dynamic Programming) form\, i.e.\, as the supremum of a collection of linear operators acting on the unkown.\\r\\nThe least-squares FEM approac h\, a variant of the nonvariational finite element method\, is based on gr adient or Hessian recovery and allows the use of FEMs of arbitrary degree. The price to pay for using higher order FEMs is the loss of discrete-leve l monotonicity (maximum principle)\, which is valid for the PDE and crucia l in proving the convergence of many degree one FEM and finite difference schemes.\\r\\nSuitable functional spaces and penalties in the least-square s's cost functional must be carefully crafted in order to ensure stability and convergence of the scheme with a good approximation of the gradient ( or Hessian) under the Cordes condition on the family of linear operators b eing optimized.\\r\\nFurthermore\, the nonlinear operator which is not nec essarily everywhere differentiable\, must be linearized in appropriate fun ctional spaces using semismooth Newton or Howard's policy iteration method . A crucial contribution of our work\, is the proof of convergence of the semismooth Newton method at the continuum level\, i.e.\, on infinite dimes ional functionals spaces. This allows an easy use of our non-monotone sche mes which provides convergence rates as well as a posteriori error estimat es.\\r\\n\\r\\nFor further information about the seminar\, please visit th is webpage [t3://page?uid=1115]. X-ALT-DESC:Least-squares finite element recovery-based methods provide a simple and practical way to approximate linear elliptic PDEs in nondiverg ence form where standard variational approach either fails or requires tec hnically complex modifications.

\nThis idea allows the creation of e fficient solvers for fully nonlinear elliptic equations\, the linearizatio n of which leaves us with an equation in nondivergence form. An important class of fully nonlinear elliptic PDEs can be written in Hamilton--Jacobi- -Bellman (Dynamic Programming) form\, i.e.\, as the supremum of a collecti on of linear operators acting on the unkown.

\nThe least-squares FEM approach\, a variant of the nonvariational finite element method\, is bas ed on gradient or Hessian recovery and allows the use of FEMs of arbitrary degree. The price to pay for using higher order FEMs is the loss of discr ete-level monotonicity (maximum principle)\, which is valid for the PDE an d crucial in proving the convergence of many degree one FEM and finite dif ference schemes.

\nSuitable functional spaces and penalties in the l east-squares's cost functional must be carefully crafted in order to ensur e stability and convergence of the scheme with a good approximation of the gradient (or Hessian) under the Cordes condition on the family of linear operators being optimized.

\nFurthermore\, the nonlinear operator wh ich is not necessarily everywhere differentiable\, must be linearized in a ppropriate functional spaces using semismooth Newton or Howard's policy it eration method. A crucial contribution of our work\, is the proof of conve rgence of the semismooth Newton method at the continuum level\, i.e.\, on infinite dimesional functionals spaces. This allows an easy use of our non -monotone schemes which provides convergence rates as well as a posteriori error estimates.

\n\nFor further information about the seminar\, pl ease visit this webpage.

DTEND;TZID=Europe/Zurich:20230421T120000 END:VEVENT BEGIN:VEVENT UID:news1475@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230413T104028 DTSTART;TZID=Europe/Zurich:20230419T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Stefano Spirito (Univers ità degli Studi dell'Aquila) DESCRIPTION:I will review the existence and uniqueness theory of a model fo r viscoelastic materials of Kelvin-Voigt type with large strain. In partic ular\, I will first review the existence theory in L2\, and then show that also propagation of H1-regularity for the deformation gradient of weak so lutions in two and three dimensions holds. Moreover\, in two dimensions it is also possible to prove uniqueness of weak solutions. Additional pro pagation of higher regularity can be obtained\, leading to a global in tim e existence of smooth solutions. Joint work with K. Koumatos (U. of Sussex )\, C. Lattanzio (UnivAQ) and A. Tzavaras (KAUST). X-ALT-DESC:I will review the existence and uniqueness theory of a model for viscoelastic materials of Kelvin-Voigt type with large strain. In part icular\, I will first review the existence theory in L2\, and then show th at also propagation of H1-regularity for the deformation gradient of weak solutions in two and three dimensions holds. \; \;Moreover\, in tw o dimensions it is also possible to prove uniqueness of weak solutions. Ad ditional propagation of higher regularity can be obtained\, leading to a g lobal in time existence of smooth solutions. Joint work with K. Koumatos ( U. of Sussex)\, C. Lattanzio (UnivAQ) and A. Tzavaras (KAUST).

DTEND;TZID=Europe/Zurich:20230419T160000 END:VEVENT BEGIN:VEVENT UID:news1503@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230404T115151 DTSTART;TZID=Europe/Zurich:20230417T171500 SUMMARY:Beyond Open Data DESCRIPTION:Main presentation Georges-Simon Ulrich\, Director General of th e Federal Statistical Office "Beyond Open Data: Data in the Domain of Fede ral Statistics for Research"\\r\\n Additional short presentations Jonas Bi eri\, Head of Data and Process Management at the Statistical Office of the Canton Basel-Stadt "Open Government Data for\, with and from Reproducible Research"\\r\\nSilke Bellanger\, University Library Basel "Research Data Management at the University of Basel"\\r\\n An aperitif will be offered a fterwards. No registration is required. X-ALT-DESC:**Main presentation**

Georges-Simon
Ulrich\, Director General of the Federal Statistical Office**"Beyond Open Data: Data in the Domain of Federal Statistics for Research"
**

**Additional short presentations**

Jonas Bieri\, Head of Data and Process Management at the Stati
stical Office of the Canton Basel-Stadt**"Open Government Dat
a for\, with and from Reproducible Research"**

Silke Bellan
ger\, University Library Basel**"Research Data Management at
the University of Basel"**

An aperitif will be offer
ed afterwards.

No registration is required.

We describe a fast method for solving elliptic PDEs with unce rtain coefficients using kernel-based interpolation over a rank-1 lattice point set [1]. By representing the input random field of the system using a model proposed by Kaarnioja\, Kuo\, and Sloan [2]\, in which a countable number of independent random variables enter the random field as periodic functions\, it is shown that the kernel interpolant can be constructed fo r the PDE solution (or some quantity of interest thereof) as a function of the stochastic variables in a highly efficient manner using fast Fourier transform. The method works well even when the stochastic dimension of the problem is large\, and we obtain rigorous error bounds which are independ ent of the stochastic dimension of the problem. We also outline some techn iques that can be used to further improve the approximation error and comp utational complexity of the method [3].

\n\nReferences:

\n[1] V. Kaarnioja\, Y. Kazashi\, F. Y. Kuo\, F. Nobile\, and I. H. Sloan. Fast approximation by periodic kernel-based lattice-point interpolation with ap plication in uncertainty quantification. Numer. Math. 150:33-77\, 2022.

\n[2] V. Kaarnioja\, F. Y. Kuo\, and I. H. Sloan. Uncertainty quantifi cation using periodic random variables. SIAM J. Numer. Anal. 58(2):1068-10 91\, 2020.

\n[3] V. Kaarnioja\, F. Y. Kuo\, and I. H. Sloan. Lattice -based kernel approximation and serendipitous weights for parametric PDEs in very high dimensions. Preprint 2023\, arXiv:2303.17755 [math.NA].

\n \nFor further information about the seminar\, please visit this webpag e.

DTEND;TZID=Europe/Zurich:20230414T120000 END:VEVENT BEGIN:VEVENT UID:news1495@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230330T145748 DTSTART;TZID=Europe/Zurich:20230405T121500 SUMMARY:Bernoullis Tafelrunde: Pascal Oswald (Johannes Gutenberg Universit ät Mainz) DESCRIPTION:abstract [t3://file?uid=3351] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230405T130000 END:VEVENT BEGIN:VEVENT UID:news1496@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230322T165202 DTSTART;TZID=Europe/Zurich:20230327T121500 SUMMARY:Bernoullis Tafelrunde: Marcello Negri (Universität Basel) DESCRIPTION:abstract [t3://file?uid=3348] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230327T130000 END:VEVENT BEGIN:VEVENT UID:news1443@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230223T094850 DTSTART;TZID=Europe/Zurich:20230323T161500 SUMMARY:Public inaugural lecture of Prof. Dr. Ivan Dokmanić DESCRIPTION:The Department of Mathematics and Computer Science kindly invit es you to the inaugural lecture of Prof. Dr. Ivan Dokmanić ein.\\r\\nAfte r the lecture an apéro will be offered. X-ALT-DESC:The Department of Mathematics and Computer Science kindly inv ites you to the inaugural lecture of Prof. Dr. Ivan Dokmanić ein.

\nAfter the lecture an apéro will be offered.

DTEND;TZID=Europe/Zurich:20230323T171500 END:VEVENT BEGIN:VEVENT UID:news1467@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230125T171400 DTSTART;TZID=Europe/Zurich:20230322T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Mickaël Latocca (Univer sité d'Évry) DESCRIPTION:In an incompressible fluid\, the pressure is governed by the el liptic equation $-\\Delta p = \\div \\div u \\otimes u$ and a Neuman-type boundary condition\, where $u$ stands for the divergence-free velocity vec tor field. The main goal of this talk is to explain why one expects that $p$ has Double Hölder regularity (with respect to that of $u$) and how on e can rigourously prove such a fact in a bounded domain. The results prese nted in this talk were obtained in collaboation with Luigi De Rosa (Basel) and Giorgio Stefani (SISSA). X-ALT-DESC:In an incompressible fluid\, the pressure is governed by the elliptic equation $-\\Delta p = \\div \\div u \\otimes u$ and a Neuman-typ e boundary condition\, where $u$ stands for the divergence-free velocity v ector field. \;The main goal of this talk is to explain why one expect s that $p$ has Double Hölder regularity (with respect to that of $u$) and how one can rigourously prove such a fact in a bounded domain. The result s presented in this talk were obtained in collaboation with Luigi De Rosa (Basel) and Giorgio Stefani (SISSA). \;

DTEND;TZID=Europe/Zurich:20230322T160000 END:VEVENT BEGIN:VEVENT UID:news1487@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230313T074957 DTSTART;TZID=Europe/Zurich:20230321T170000 SUMMARY:Local (Government) Data in Research DESCRIPTION:On March 22\, the PARIS21 Spring Meeting will take place in Bas el on the topic «Going local to leave no one behind: The role of subnatio nal data». On the evening before\, the Responsible Digital Society Resear ch Network of the University of Basel is organising a public event.\\r\\n\ \r\\n17:00 s.t. Welcome\\r\\n 17:05 Presentations\\r\\nProf. Dr. Christine Alewell\, Department of Environmental Sciences\, University of Basel “B ig data for soil health assessment: from global erosion modelling to local remote mapping approaches” Prof. Dr. Giusi Moffa\, Department of Mathem atics and Computer Science\, University of Basel “From real-world data t o intervention effects: tales from the health sciences” Prof. Dr. Lukas Rosenthaler\, Digital Humanities Lab\, University of Basel “The Digital Transformation in the Humanities - Open Data as an Opportunity for Culture and Society”\\r\\n 18:00 Panel Discussion: Open (Government) Data in Re search Panelists: • Prof. Dr. Christine Alewell\, Univ. Basel • Jonas Bieri\, Head of Data and Process Management at the Statistical Office of t he Canton Basel-Stadt • Prof. Dr. Giusi Moffa\, Univ. Basel • Prof. Dr . Lukas Rosenthaler\, Univ. Basel\\r\\nModeration:\\r\\nAndreas Amsler [ht tps://fogdt.ch/about/]\, former Lead of Open Government Data at the Canton Zurich\\r\\nThe event is followed by an apéro. No registration required. X-ALT-DESC:On March 22\, the PARIS21 Spring Meeting will take place in B asel on the topic «Going local to leave no one behind: The role of subnat ional data». On the evening before\, the Responsible Digital Society Rese arch Network of the University of Basel is organising a public event.

\ n\n**17:00 s.t. Welcome**

**17:05 Pre
sentations**

__Prof. Dr. Christine Alewell__\, Departmen
t of Environmental Sciences\, University of Basel

“Big data for so
il health assessment: from global erosion modelling to local

remote
mapping approaches”__Prof. Dr. Giusi Moffa__\, Department of M
athematics and Computer Science\, University of Basel

“From real-w
orld data to intervention effects: tales from the health sciences”__Prof. Dr. Lukas Rosenthaler__\, Digital Humanities Lab\, University
of Basel

“The Digital Transformation in the Humanities - Open Data
as an Opportunity

for Culture and Society”

**18:00 Panel Discussion: Open (Government) Data in Research**

Panelists:

• Prof. Dr. Christine Alewell\, Univ. Basel

•
Jonas Bieri\, Head of Data and Process Management at the Statistical Offic
e

of the Canton Basel-Stadt

• Prof. Dr. Giusi Moffa\, Univ.
Basel

• Prof. Dr. Lukas Rosenthaler\, Univ. Basel

Moderati on:

\nAndreas Amsler\, former Lead of Open Government Data at the Canton Zurich

\nThe event is fol lowed by an apéro. No registration required.

DTEND;TZID=Europe/Zurich:20230321T183000 END:VEVENT BEGIN:VEVENT UID:news1494@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230315T134730 DTSTART;TZID=Europe/Zurich:20230320T121500 SUMMARY:Bernoullis Tafelrunde: Dominik Nowak (University of Basel) DESCRIPTION:Abstract [t3://file?uid=3344] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20230320T130000 END:VEVENT BEGIN:VEVENT UID:news1468@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230403T123812 DTSTART;TZID=Europe/Zurich:20230317T110000 SUMMARY:Seminar in Numerical Analysis: Marc Dambrine (Université de Pau et des Pays de l'Adour) DESCRIPTION:As it is often the case in optimization\, the solution of a sha pe problem is sensitive to the parameters of the problem. For example\, th e loading of a structure to be optimised is known in an imprecise way. In this talk\, I will present the different approaches that have been recentl y proposed to incorporate these uncertainties in the definition of the obj ective. I will present numerical illustrations from structural optimizatio n.\\r\\n\\r\\nFor further information about the seminar\, please visit thi s webpage [t3://page?uid=1115]. X-ALT-DESC:As it is often the case in optimization\, the solution of a s hape problem is sensitive to the parameters of the problem. For example\, the loading of a structure to be optimised is known in an imprecise way. I n this talk\, I will present the different approaches that have been recen tly proposed to incorporate these uncertainties in the definition of the o bjective. I will present numerical illustrations from structural optimizat ion.

\n\nFor further information about the seminar\, please visit th is webpage.

DTEND;TZID=Europe/Zurich:20230317T120000 END:VEVENT BEGIN:VEVENT UID:news1490@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230317T075118 DTSTART;TZID=Europe/Zurich:20230316T170000 SUMMARY:Online-Info Evening Master DESCRIPTION:On Thursday\, March 16\, 2023\, the University of Basel will ho st this year's Online-Info Evening for Masters degrees. Between 5:00 p.m. and 7:00 p.m.\, various Master's degree programs will be presented.\\r\\n\ \r\\nActuarial Science 5:30 – 5:45 p.m.: Presentation of the Master's de gree in Actuarial Science (Dr. Nils Rüfenacht) 5:45 p.m. – 6:30 p.m.: O pen consultation (Dr. Nils Rüfenacht\, lecturer\, and Jolanda Bucher\, st udy coordinator) 6:30 p.m. – 7:00 p.m.: Meet our Master's students \\r \\n\\r\\nData Science 5:30 – 7:00 p.m.: Presentation of the Master's deg ree in Data Science (Prof. Ivan Dokmanić) Afterward: Open consultation (D r. Sabine Meinel\, study coordinator) \\r\\n\\r\\nComputer Science 5:30 p.m. – 7:00 p.m.: Presentation of the Master's degree in Computer Scienc e (Prof. Heiko Schuldt) Afterward: Open consultation (Dr. Heike Freiberger \, study coordinator) \\r\\n\\r\\nMathematics 5:30 p.m. – 7:00 p.m.: P resentation of the Master’s specialization modules (Introduction by Prof . Enno Lenzmann\, followed by consolidation from Prof. Gianluca Crippa\, P rof. Marcus Grote\, and Prof. Philipp Habegger) Afterward: Open consultati on (Heidi Karypidis\, study coordinator) \\r\\n\\r\\nRegistration [https ://join.events.unibas.ch/event.php?vnrtoken=JE/j6X76UWABsdO1poSJ+UBFLc/AZe PfqTY+jRLQVIZrfCF6dzHpWdJ1s4ENYg38OuhuX/YzHLm3SGJIu7QlE4A=] is requested.\ \r\\nYou can dial in at any time during the program. You can find more inf ormation about other degree programs here [https://www.unibas.ch/en/Infoev ening-Master.html]. X-ALT-DESC:On Thursday\, March 16\, 2023\, the University of Basel will host this year's Online-Info Evening for Masters degrees. Between 5:00 p.m . and 7:00 p.m.\, various Master's degree programs will be presented.

\ n\n**Actuarial Science****5:30 – 5:4
5 p.m.:** Presentation of the Master's degree in Actuarial Science
(Dr. Nils Rüfenacht)**5:45 p.m. – 6:30 p.m.:** Open
consultation (Dr. Nils Rüfenacht\, lecturer\, and Jolanda Bucher\, study
coordinator)**6:30 p.m. – 7:00 p.m.:** Meet our Mas
ter's students

\;

**Data Science****5:30 – 7:00 p.m.:** Presentation of the Master's
degree in Data Science (Prof. Ivan Dokmanić)**Afterward: Open consultation (Dr. Sabine Meinel\, study coordinator) &nbs
p\;**

**Computer Science****5:30
p.m. – 7:00 p.m.:** Presentation of the Master's degree in Comput
er Science (Prof. Heiko Schuldt)**Afterward:** Open co
nsultation (Dr. Heike Freiberger\, study coordinator)

\;

**Mathematics5:30 p.m. – 7:00 p
.m.: Presentation of the Master’s specialization modules (Intro
duction by Prof. Enno Lenzmann\, followed by consolidation from Prof. Gian
luca Crippa\, Prof. Marcus Grote\, and Prof. Philipp Habegger)**Open consultation (Heidi Karypidis\, study coordina
tor)

\;

**Registration** is requeste
d.

You can dial in at any time during the program.

You can f
ind more information about other degree programs **here**.

The Dirac equation is one of the fundamental equations in rel ativistic quantum mechanics\, widely used in a large number of application s from physics to quantum chemistry. The aim of this talk will be to discu ss some recent results\, together with a number of open questions\, concer ning the dynamics for this model: after briefly reviewing the main propert ies of the Dirac operator and providing some background and motivations fr om the theory of linear dispersive PDEs\, we shall focus in particular on the cases of the Dirac-Coulomb equation and of the Dirac equation on non f lat manifolds\, showing how some linear estimates (in particular\, Stricha rtz estimates) can be obtained by exploiting various properties of the ope rator.

DTEND;TZID=Europe/Zurich:20230315T161500 END:VEVENT BEGIN:VEVENT UID:news1477@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230303T112515 DTSTART;TZID=Europe/Zurich:20230314T180000 SUMMARY:Why do mathematicians celebrate March 14th with pie DESCRIPTION:Attention\, friends of calculus and calories - the next episode of “Behind the science” at the Novartis Pavillon is for you! Join us and Philipp Habegger\, professor for number theory at the University of Ba sel\, for an exciting trip into the world of mathematics\, where fascinati ng curiosities await. And there will be pie!\\r\\nHost: Prof. Dr. Botond R oska\, founding director IOB\\r\\nParticipation is free of charge\, sign u p here [https://www.campus.novartis.com/en/registration-pi_e-day]! The eve nt will be held in English\, number of seats is limited. X-ALT-DESC:Attention\, friends of calculus and calories - the next episo
de of “Behind the science” at the Novartis Pavillon is for you!

Join us and Philipp Habegger\, professor for number theory at the Universi
ty of Basel\, for an exciting trip into the world of mathematics\, where f
ascinating curiosities await.

And there will be pie!

Host: P rof. Dr. Botond Roska\, founding director IOB

\nParticipation is fre
e of charge\, sign up **here**! The event will be held in Englis
h\, number of seats is limited.

Apero afterwards! poster

DTEND;TZID=Europe/Zurich:20230309T183000 END:VEVENT BEGIN:VEVENT UID:news1465@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230119T132638 DTSTART;TZID=Europe/Zurich:20230308T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Maria Ahrend (Uni Basel) DESCRIPTION:Maria Ahrend will defend her PhD thesis on fractional Liouville equations and Calogero-Moser NLS. X-ALT-DESC:Maria Ahrend will defend her PhD thesis on fractional Liouvil le equations and Calogero-Moser NLS.

DTEND;TZID=Europe/Zurich:20230309T160000 END:VEVENT BEGIN:VEVENT UID:news1476@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230304T163156 DTSTART;TZID=Europe/Zurich:20230307T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Zineb Hassainia (New Yor k University Abu Dhabi) [special time!] DESCRIPTION:In this talk\, I will discuss a recent result concerning the co nstruction of quasi-periodic vortex patch solutions with one hole for th e 2D-Euler equations. These structures exist close to any annulus provided that its modulus belongs to a Cantor set with almost full Lebesgue measur e. The proof is based on a KAM reducibility scheme and a Nash-Moser iterative scheme. This is a joint work with Taoufik Hmidi and Emeric Roull ey. X-ALT-DESC:In this talk\, I will discuss a recent result concerning the construction of quasi-periodic vortex patch solutions \; with one hole for the 2D-Euler equations. These structures exist close to any annulus p rovided that its modulus belongs to a Cantor set with almost full Lebesgue measure. The proof is based on \; a KAM reducibility scheme \; an d a \; Nash-Moser iterative scheme. This is a joint work with Taoufik Hmidi and Emeric Roulley.

DTEND;TZID=Europe/Zurich:20230307T160000 END:VEVENT BEGIN:VEVENT UID:news1442@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230119T083934 DTSTART;TZID=Europe/Zurich:20230223T161500 SUMMARY:Public inaugural lecture of Prof. Dr. Aurelien Lucchi DESCRIPTION:The Department of Mathematics and Computer Science kindly invit es you to the inaugural lecture of Prof. Dr. Aurelien Lucchi.\\r\\nAfter t he lecture an apéro will be offered. X-ALT-DESC:The Department of Mathematics and Computer Science kindly inv ites you to the inaugural lecture of Prof. Dr. Aurelien Lucchi.

\nAf ter the lecture an apéro will be offered.

DTEND;TZID=Europe/Zurich:20230223T171500 END:VEVENT BEGIN:VEVENT UID:news1470@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230131T153947 DTSTART;TZID=Europe/Zurich:20230222T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Peter Pickl (Universitä t Tübingen) DESCRIPTION:The derivation of the Vlasov equation from Newtonian mechanics is an old problem in mathematical physics. But while the most interest ing interactions in nature have singularities\, one typically assumes some Lipschitz condition on the interaction force for its microscopic derivation. Recent developments have given results\, where the interac tion force gets singular when the particle number N tends to infinity\, us ually by mollifying or cutting the singularity with a N-dependent moll ifier or cut-off parameter. In the talk I will present most recent develop ments and new results on this topic. X-ALT-DESC:The derivation of the Vlasov equation from Newtonian mechanic
s is an \; \;

old problem in

mathematical physics. But
while the most interesting interactions in \; \;

nature hav
e singularities\,

one typically assumes some Lipschitz condition on
the interaction \; \;

force for its microscopic

deriva
tion. Recent developments have given results\, where the \; \;

interaction force gets singular

when the particle number N tends
to infinity\, usually by mollifying \; \;

or cutting the sin
gularity

with a N-dependent mollifier or cut-off parameter.

In
the talk I will present most recent developments and new results on \
; \;

this topic.

For more information and the link to the event please visit t he website of the Warwick Mathematics Institute (WMI).

END:VEVENT BEGIN:VEVENT UID:news1440@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20230109T092602 DTSTART;TZID=Europe/Zurich:20230127T090000 SUMMARY:P2P Basel DESCRIPTION:Secure Scuttlebutt (SSB) is an application-level\, secure and p ersisted publish/subscribe system that has gained popularity in the decent ralized Web movement. The aim of this workshop is to bring together resear chers\, software builders and members of the SSB community to study the pr operties and potential of Secure Scuttlebutt. The workshop is open to othe r decentralized approaches and networking technologies e.g. DAT\, Holochai n\, IPFS or SOLID\, as problems and technologies often have considerable s imilarities. Also\, a SSB tutorial precedes the workshop\, helping people to get familiar with the Secure Scuttlebutt technology and value system in short time. Limited travel and accommodation grants are available to help facilitate attendance from people without institutional funding.\\r\\nFor more information\, please visit the event website [https://p2p-basel.org/ ]. X-ALT-DESC:Secure Scuttlebutt (SSB) is an application-level\, secure and persisted publish/subscribe system that has gained popularity in the dece ntralized Web movement. The aim of this workshop is to bring together rese archers\, software builders and members of the SSB community to study the properties and potential of Secure Scuttlebutt. The workshop is open to ot her decentralized approaches and networking technologies e.g. DAT\, Holoch ain\, IPFS or SOLID\, as problems and technologies often have considerable similarities. Also\, a SSB tutorial precedes the workshop\, helping peopl e to get familiar with the Secure Scuttlebutt technology and value system in short time. Limited travel and accommodation grants are available to he lp facilitate attendance from people without institutional funding.

\n< p>For more information\, please visit theThe Department of Mathematics and Computer Science will be pr esent at the Basel Museums Night again this year:

\nThe DBIS researc h group will show the "Virtual Museum" at the Historisches Museum Basel (H BM) in the Barfüsserkirche. From 18:00 - 02:00 visitors can create their own virtual HMB exhibition.

\nFor more information about the program
\, please visit the **Museum Ni
ght website**.

Singular stochastic partial differential equations (SPDEs) of the form \;

\n∂_{t}u \;= \;△u \;+ \
;F \;(u\, ∂_{x}u\, ξ)\, \;

where \;ξ \ ;is an irregular driving noise\, arise in a variety of situations from qua ntum field theory to probability. After introducing some specific examples \, we describe the main difficulty they share\; they are singular due to t he irregularity of the driving noise \;ξ.

\nIn the first part o f the talk we discuss a simple example where using the so-called “Da Pra to-Debusche trick” is sufficient to deal with this difficulty. In the se cond half\, we give a birds-eye view on how regularity structures provide a solution theory for such equations. In particular\, we explain the role of subcriticality (super-renormalisability) and (half) Feynman diagrams in this theory. Lastly\, we shall mention some recent results on the class o f differential operators that are compatible with this general machinery a nd how this relates to the geometry of the underlying space.

DTEND;TZID=Europe/Zurich:20221221T160000 END:VEVENT BEGIN:VEVENT UID:news1427@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221209T160417 DTSTART;TZID=Europe/Zurich:20221219T121500 SUMMARY:Bernoullis Tafelrunde: Frieder Jäckel (University of Bonn) DESCRIPTION:Abstract. [t3://file?uid=3291] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20221219T130000 END:VEVENT BEGIN:VEVENT UID:news1435@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221202T183344 DTSTART;TZID=Europe/Zurich:20221216T123000 SUMMARY:From clinical decision support and explainable AI towards digital t wins DESCRIPTION:Abstract:\\r\\nThis presentation will summarize the main work d one in the research group of Henning Müller at the HES-SO Valais in Sierr e on medical multimodal data analysis. This work ranges from image creatio n differences\, to biomarker extraction from radiology and histopathology images towards clinical decision support. An essential part of integrating the mainly deep learning based approaches is to be able to explain decisi ons and predictions\, whereas deep learning networks are usually black box es.\\r\\nAll these aspects can help to create a digital view on patients w here several options for prevention or treatment can be adapted interactiv ely. This is also name digital twins in industry and is a concept that we expect to become more common in the medical field when longitudinal data o n patients is available.\\r\\n\\r\\nBiography:\\r\\nHenning Müller studie d medical informatics at the University of Heidelberg\, Germany\, then wor ked at Daimler-Benz research in Portland\, OR\, USA. From 1998-2002 he wor ked on his PhD degree in computer vision at the University of Geneva\, Swi tzerland with a research stay at Monash University\, Melbourne\, Australia . Since 2002\, Henning has been working for the medical informatics servic e at the University Hospital of Geneva. Since 2007\, he has been a full pr ofessor at the HES-SO Valais and since 2011 he is responsible for the eHea lth unit of the school. Since 2014\, he is also professor at the medical f aculty of the University of Geneva. In 2015/2016 he was on sabbatical at t he Martinos Center\, part of Harvard Medical School in Boston\, MA\, USA t o focus on research activities. Henning is coordinator of the ExaMode EU p roject\, was coordinator of the Khresmoi EU project\, scientific coordinat or of the VISCERAL EU project. Since early 2020 he is also a member of the Swiss National Research Council. X-ALT-DESC:__Abstract:__

This presentation will summarize the main work done in the research group of Henning Müller at the HES-SO Val ais in Sierre on medical multimodal data analysis. This work ranges from i mage creation differences\, to biomarker extraction from radiology and his topathology images towards clinical decision support. An essential part of integrating the mainly deep learning based approaches is to be able to ex plain decisions and predictions\, whereas deep learning networks are usual ly black boxes.

\nAll these aspects can help to create a digital vie w on patients where several options for prevention or treatment can be ada pted interactively. This is also name digital twins in industry and is a c oncept that we expect to become more common in the medical field when long itudinal data on patients is available.

\n\n__Biography:__

This talk is devoted to non-overlapping Schwarz domain decomp
osition methods for the resolution of high frequency flow acoustics proble
ms of industrial relevance. First\, we will present recent advances on non
-reflecting boundary techniques that provide local approximations to the D
irichlet-to-Neumann operator for convected and heterogeneous time-harmonic
wave propagation problems [1]. Then we will show how to adapt a generic d
omain decomposition framework to flow acoustics\, based on these newly des
igned transmission conditions\, and highlight the benefit of the approach
on the simulation of three-dimensional noise radiation of a high by-pass r
atio turbofan engine intake [2].

[1] Marchner\, P.\, Antoine\
, X.\, Geuzaine\, C.\, &\; Bériot\, H. (2022). Construction and numeri
cal assessment of local absorbing boundary conditions for heterogeneous ti
me-harmonic acoustic problems. SIAM Journal on Applied Mathematics\, 82(2)
\, 476-501.

[2] Lieu\, A.\, Marchner\, P.\, Gabard\, G.\, Ber
iot\, H.\, Antoine\, X.\, &\; Geuzaine\, C. (2020). A non-overlapping S
chwarz domain decomposition method with high-order finite elements for flo
w acoustics. Computer Methods in Applied Mechanics and Engineering\, 369\,
113223.

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20221216T120000 END:VEVENT BEGIN:VEVENT UID:news1407@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221202T151906 DTSTART;TZID=Europe/Zurich:20221212T121500 SUMMARY:Bernoullis Tafelrunde: Aurore Boitrel (University of Angers) DESCRIPTION:Abstract [t3://file?uid=3284] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20221212T130000 END:VEVENT BEGIN:VEVENT UID:news1410@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221130T142441 DTSTART;TZID=Europe/Zurich:20221209T110000 SUMMARY:Seminar in Numerical Analysis: Patrick Ciarlet (ENSTA Paris) DESCRIPTION:Variational formulations are a popular tool to analyse linear P DEs (eg. neutron diffusion\, Maxwell equations\, Stokes equations ...)\, a nd it also provides a convenient basis to design numerical methods to solv e them. Of paramount importance is the inf-sup condition\, designed by Lad yzhenskaya\, Necas\, Babuska and Brezzi in the 1960s and 1970s. As is well -known\, it provides sharp conditions to prove well-posedness of the probl em\, namely existence and uniqueness of the solution\, and continuous depe ndence with respect to the data. Then\, to solve the approximate\, or disc rete\, problems\, there is the (uniform) discrete inf-sup condition\, to e nsure existence of the approximate solutions\, and convergence of those so lutions to the exact solution. Often\, the two sides of this problem (exac t and approximate) are handled separately\, or at least no explicit connec tion is made between the two.\\r\\nIn this talk\, I will focus on an appro ach that is completely equivalent to the inf-sup condition for problems se t in Hilbert spaces\, the T-coercivity approach. This approach relies on t he design of an explicit operator to realize the inf-sup condition. If the operator is carefully chosen\, it can provide useful insight for a straig htforward definition of the approximation of the exact problem. As a matte r of fact\, the derivation of the discrete inf-sup condition often becomes elementary\, at least when one considers conforming methods\, that is whe n the discrete spaces are subspaces of the exact Hilbert spaces. In this w ay\, both the exact and the approximate problems are considered\, analysed and solved at once.\\r\\nIn itself\, T-coercivity is not a new theory\, h owever it seems that some of its strengths have been overlooked\, and that \, if used properly\, it can be a simple\, yet powerful tool to analyse an d solve linear PDEs. In particular\, it provides guidelines such as\, whic h abstract tools and which numerical methods are the most “natural” to analyse and solve the problem at hand. In other words\, it allows one to select simply appropriate tools in the mathematical\, or numerical\, toolb oxes. This claim will be illustrated on classical linear PDEs\, and for so me generalizations of those models.\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Variational formulations are a popular tool to analyse linear
PDEs (eg. neutron diffusion\, Maxwell equations\, Stokes equations ...)\,
and it also provides a convenient basis to design numerical methods to so
lve them. Of paramount importance is the **inf-sup condition**\, designed by Ladyzhenskaya\, Necas\, Babuska and Brezzi in the 1960s an
d 1970s. As is well-known\, it provides sharp conditions to prove well-pos
edness of the problem\, namely existence and uniqueness of the solution\,
and continuous dependence with respect to the data. Then\, to solve the ap
proximate\, or discrete\, problems\, there is the **(uniform) discre
te inf-sup condition**\, to ensure existence of the approximate sol
utions\, and convergence of those solutions to the exact solution. Often\,
the two sides of this problem (exact and approximate) are handled separat
ely\, or at least no explicit connection is made between the two.

In this talk\, I will focus on an approach that is completely equivalent t
o the inf-sup condition for problems set in Hilbert spaces\, the **T
-coercivity approach**. This approach relies on the design of an

In itself\, T-coercivity is not a new theory\, however it seems that some of its strengths have been overlooked\, and that\, if used properly\, it can be a simple\, yet powerful tool to analyse and solv e linear PDEs. In particular\, it provides guidelines such as\, which abst ract tools and which numerical methods are the most “natural” to analy se and solve the problem at hand. In other words\, it allows one to select simply appropriate tools in the mathematical\, or numerical\, toolboxes. This claim will be illustrated on classical linear PDEs\, and for some gen eralizations of those models.

\nFor further information about the se minar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20221209T120000 END:VEVENT BEGIN:VEVENT UID:news1419@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221128T102752 DTSTART;TZID=Europe/Zurich:20221207T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Hyunju Kwon (ETH Zurich) DESCRIPTION:Smooth (spatially periodic) solutions to the incompressible 3D Euler equations have kinetic energy conservation in every local region\, w hile turbulent flows exhibit anomalous dissipation of energy. Toward verif ication of the anomalous dissipation\, Onsager theorem has been establishe d\, which says that the threshold Hölder regularity of the total kinetic energy conservation is 1/3. As a next step\, we discuss a strong Onsager c onjecture\, which combines the Onsager theorem with the local energy inequ ality. X-ALT-DESC:Smooth (spatially periodic) solutions to the incompressible 3 D Euler equations have kinetic energy conservation in every local region\, while turbulent flows exhibit anomalous dissipation of energy. Toward ver ification of the anomalous dissipation\, Onsager theorem has been establis hed\, which says that the threshold Hölder regularity of the total kineti c energy conservation is 1/3. As a next step\, we discuss a strong Onsager conjecture\, which combines the Onsager theorem with the local energy ine quality.

DTEND;TZID=Europe/Zurich:20221207T160000 END:VEVENT BEGIN:VEVENT UID:news1426@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221125T110626 DTSTART;TZID=Europe/Zurich:20221205T121500 SUMMARY:Bernoullis Tafelrunde: Ulrik Hansen (University of Fribourg) DESCRIPTION:Abstract. [t3://file?uid=3282] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20221205T130000 END:VEVENT BEGIN:VEVENT UID:news1401@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221108T142058 DTSTART;TZID=Europe/Zurich:20221202T173000 SUMMARY:BZ Seminar in Analysis: Roberta Bianchini (IAC-CNR Roma) DESCRIPTION:We will be interested in the analysis of continuously stratifie d fluids under the influence of gravity. The system is obtained by a line arization of the equations of incompressible non-homogeneous fluids arou nd a background density profile that increases with depth (spectrally sta ble density profile). I will present some recent results concerning stabi lity issues and the long-time behaviour of solutions. X-ALT-DESC:We will be interested in the analysis of continuously stratif ied fluids under the influence of gravity. \;The system is obtained by a linearization of the equations \;of incompressible non-homogeneous fluids \;around a background density \;profile that increases with depth (spectrally stable density profile). \;I will present some rece nt results concerning stability issues and the long-time behaviour of solu tions.

DTEND;TZID=Europe/Zurich:20221202T183000 END:VEVENT BEGIN:VEVENT UID:news1400@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221108T142014 DTSTART;TZID=Europe/Zurich:20221202T160000 SUMMARY:BZ Seminar in Analysis: Aleksandr Logunov (University of Geneva) DESCRIPTION:The functions sin(kx)\, cos(kx) are positive on half of the cir cle and are negative on another half. D.Armitage and S.Gardiner conjectur ed that the sign of spherical harmonics is always positive on a portion o f the sphere bounded below by a positive constant\, which depends only on the dimension of the sphere. This phenomenon is called quasi-symmetry of sign and it was proved by H.Donnelly and C.Fefferman. Nazarov\, Polterov ich and Sodin suggested that quasi-symmetry of sign happens on small sca les in the regime when the eigenvalue grows to infinity. We will talk ab out the distribution of sign based on a joint work in progress with Fedya Nazarov. X-ALT-DESC:The functions sin(kx)\, cos(kx) are positive on half of the c ircle and are negative on another half. \;D.Armitage and S.Gardiner co njectured that the sign of spherical harmonics is always positive on a por tion \;of the sphere bounded below by a positive constant\, \;whic h depends only on the dimension of the sphere. \;This phenomenon is ca lled quasi-symmetry of sign and it was proved by H.Donnelly and C.Fefferma n. \;Nazarov\, Polterovich and Sodin suggested that \;quasi-symmet ry \;of sign happens on small scales in the \;regime when the eige nvalue grows to infinity. \;We will talk about the distribution of sig n based on a joint \;work in progress with Fedya Nazarov.

DTEND;TZID=Europe/Zurich:20221202T170000 END:VEVENT BEGIN:VEVENT UID:news1409@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220928T143806 DTSTART;TZID=Europe/Zurich:20221202T110000 SUMMARY:Seminar in Numerical Analysis: Sébastien Imperiale (Inria — LMS\ , Ecole Polytechnique\, CNRS — Université Paris-Saclay\, MΞDISIM) DESCRIPTION:The objective of this work is to propose and analyze numerical schemes to solve transient wave propagation problems that are exponentiall y stable (i.e. the solution decays to zero exponentially fast). Applicatio ns are in data assimilation strategies or the discretisation of absorbing boundary conditions. More precisely the aim of our work is to propose a di scretization process that enables to preserve the exponential stability at the discrete level as well as a high order consistency when using a high- order finite element approximation. The main idea is to add to the wave eq uation a stabilizing term which damps the high-frequency oscillating compo nents of the solutions such as spurious waves. This term is built from a d iscrete multiplier analysis that proves the exponential stability of the s emi-discrete problem at any order without affecting the order of convergen ce.\\r\\nFor further information about the seminar\, please visit this web page [t3://page?uid=1115]. X-ALT-DESC:The objective of this work is to propose and analyze numerica l schemes to solve transient wave propagation problems that are exponentia lly stable (i.e. the solution decays to zero exponentially fast). Applicat ions are in data assimilation strategies or the discretisation of absorbin g boundary conditions. More precisely the aim of our work is to propose a discretization process that enables to preserve the exponential stability at the discrete level as well as a high order consistency when using a hig h-order finite element approximation. The main idea is to add to the wave equation a stabilizing term which damps the high-frequency oscillating com ponents of the solutions such as spurious waves. This term is built from a discrete multiplier analysis that proves the exponential stability of the semi-discrete problem at any order without affecting the order of converg ence.

\nFor further information about the seminar\, please visit thi s webpage.

DTEND;TZID=Europe/Zurich:20221202T120000 END:VEVENT BEGIN:VEVENT UID:news1429@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221117T152426 DTSTART;TZID=Europe/Zurich:20221123T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Michele Dolce (EPFL) DESCRIPTION:Fluids in the ocean are often inhomogeneous\, incompressible an d\, in relevant physical regimes\, can be described by the 2D Euler-Boussi nesq system. Equilibrium states are then commonly observed to be stably st ratified\, namely the density increases with depth. We are interested in c onsidering the case when also a background shear flow is present. In the t alk\, I will describe quantitative results for small perturbations around a stably stratified Couette flow. The density variation and velocity under go an O(1/(t^{1/2})) inviscid damping while the vorticity and density grad ient grow as O(t^{1/2}) in L^2. This is precisely quantified at the linea r level. For the nonlinear problem\, the result holds on the optimal time -scale on which a perturbative regime can be considered. Namely\, given an initial perturbation of size O(eps)\, it is expected that the linear reg ime is observed up to a time-scale O(eps^{-1}). However\, we are able to control the dynamics all the way up to O(eps^{-2})\, where the perturbat ion become of size O(1) due to the linear instability. X-ALT-DESC:Fluids in the ocean are often inhomogeneous\, incompressible and\, in relevant physical regimes\, can be described by the 2D Euler-Bous sinesq system. Equilibrium states are then commonly observed to be stably stratified\, namely the density increases with depth. We are interested in considering the case when also a background shear flow is present. In the talk\, I will describe quantitative results for small perturbations aroun d a stably stratified Couette flow. The density variation and velocity und ergo an O(1/(t^{1/2})) inviscid damping while the vorticity and density gr adient grow as O(t^{1/2}) \;in L^2. This is precisely quantified at th e linear level. \;For the nonlinear problem\, the result holds on the optimal time-scale on which a perturbative regime can be considered. Namel y\, given an initial perturbation of size O(eps)\, \;it is expected th at the linear regime is observed up to a time-scale O(eps^{-1}). However\, \;we are able to control the dynamics all the way up to \;O(eps^{ -2})\, where \;the perturbation become of size O(1) \;due to the l inear instability.

DTEND;TZID=Europe/Zurich:20221123T160000 END:VEVENT BEGIN:VEVENT UID:news1408@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221110T132504 DTSTART;TZID=Europe/Zurich:20221118T110000 SUMMARY:Seminar in Numerical Analysis: Alexey Chernov (Universität Oldenbu rg) DESCRIPTION:We investigate a class of parametric elliptic eigenvalue proble ms where the coefficients (and hence the solution) may depend on a paramet er y. Understanding the regularity of the solution as a function of y is i mportant for construction of efficient numerical approximation schemes. Se veral approaches are available in the existing literature\, e.g. the comp lex-analytic argument by Andreev and Schwab (2012) and the real-variable a rgument by Gilbert et al. (2019+). The latter proof strategy is more expli cit\, but\, due to the nonlinear nature of the problem\, leads to slightly suboptimal results. In this talk we close this gap and (as a by-product) extend the analysis to the more general class of coefficients.\\r\\nFor fu rther information about the seminar\, please visit this webpage [t3://page ?uid=1115]. X-ALT-DESC:We investigate a class of parametric elliptic eigenvalue prob lems where the coefficients (and hence the solution) may depend on a param eter y. Understanding the regularity of the solution as a function of y is important for construction of efficient numerical approximation schemes. Several approaches are available in the existing literature\, e.g. \;t he complex-analytic argument by Andreev and Schwab (2012) and the real-var iable argument by Gilbert et al. (2019+). The latter proof strategy is mor e explicit\, but\, due to the nonlinear nature of the problem\, leads to s lightly suboptimal results. In this talk we close this gap and (as a by-pr oduct) extend the analysis to the more general class of coefficients.

\ nFor further information about the seminar\, please visit this webpage .

DTEND;TZID=Europe/Zurich:20221118T120000 END:VEVENT BEGIN:VEVENT UID:news1424@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221109T101811 DTSTART;TZID=Europe/Zurich:20221118T090000 SUMMARY:Bachelor Info Event DESCRIPTION:From 9:00 a.m. to 2:00 p.m.\, there will be two information mar kets at Kollegienhaus and Pharmazentrum\, where you can get specific infor mation about the study program you are considering and exchange ideas with lecturers and students. You also have the opportunity to get to know stud y programs that you might not have thought of yet. You will also receive i nformation about exchange programs\, the language center\, studying with a disability\, sports at the university\, the library\, and the admission p rocess. You can also talk to representatives of the Student Body of the Un iversity of Basel (skuba).\\r\\nCheck out the program [https://www.unibas. ch/de/Infotag-Bachelor/Programm.html?orderby=time] (in German) and plan out your day at the Bachelor Info Event. X-ALT-DESC:From 9:00 a.m. to 2:00 p.m.\, there will be two information m arkets at Kollegienhaus and Pharmazentrum\, where you can get specific inf ormation about the study program you are considering and exchange ideas wi th lecturers and students. You also have the opportunity to get to know st udy programs that you might not have thought of yet. You will also receive information about exchange programs\, the language center\, studying with a disability\, sports at the university\, the library\, and the admission process. You can also talk to representatives of the Student Body of the University of Basel (skuba).

\nCheck out the **program \; **(in German) and plan out your day at the Bachelor Info E
vent.

Following the seminal work of Bourgain in 1996\, and Burq and
Tzvetkov in 2008\, a statistical approach to nonlinear dispersive equatio
ns has developed in various contexts. \;We are interested here in Schr
ödinger equations with cubic nonlinearity (NLS) in R^d. We first recall t
he relevant probabilistic Cauchy theory \;developed by Bényi\, Oh an
d Pocovnicu in 2015 in supercritical regimes\, before specifying the \
;*norm inflation* \;instability that occurs in this context.&nb
sp\;The second part is dedicated to long-time dynamics for solutions initi
ated from these randomized initial data. We demonstrate a scattering resul
t that relies on a probabilistic version of the \;*I-method*&nb
sp\;and that allows to solve statistically the scattering conjecture for N
LS in dimension 3. \;Finally\, we present recent developments in quasi
-linear regimes\, which were initiated by Bringmann in 2019 and which we e
xploit to exhibit strong solutions to some weakly dispersive equations. Th
is last result is in collaboration with Louise Gassot and Slim Ibrahim.

**The colloquium will be held in German:**

Nebst dem Lesen und Schreiben wird auch das Programmieren im Bildungswe sen bald den Stellenwert einer Grundfertigkeit haben\, die alle Schülerin nen und Schüler im Rahmen der allgemeinen Bildung erlernen sollten. Dabei werden Fähigkeiten wie Kreativität und konstruktives Problemlösen gef ördert\, die wichtige Voraussetzungen sind\, um sich in den noch ungewiss en Berufen der Zukunft behaupten zu können. Wie aber sollen Kinder im Pri marschulalter programmieren lernen ohne fliessend Lesen und Schreiben zu k önnen? Wie gelingt der Übergang von den verspielten block-basierten Prog rammiersprachen ins „echte“ Programmieren? Und wie geht man damit um\, dass das Programmieren eine äusserst fehleranfällige Lern-Aktivität is t? Dank geeigneter Unterrichtsmaterialien und Lernumgebungen ist es mögli ch\, das Programmieren parallel zu den anderen Grundfertigkeiten zu erlern en\, fächerübergreifende Synergieeffekte zu nutzen und grundlegende Prog rammierkonzepte über viele Jahre kontinuierlich zu festigen. Wir präsent ieren unser Spiralcurriculum und die dazugehörige Lernumgebung XLogoOnlin e.

\nJacqueline Staub ist eine Schweizer Informatikerin\, die inte rnational bekannt ist für die Leitung in der Entwicklung der pädagogisch en Programmierumgebung "XLogoOnline". Diese Umgebung ermöglicht einen dur chgängigen Programmierunterricht vom Kindergarten bis zum Abitur. Jacquel ine Staub hat nach Bachelor\, Master und Doktorat in Informatik an der ETH Zürich sowie einem Lehrdiplom für Informatik den Ruf an die Universitä t Trier erhalten\, wo sie seit Januar 2022 die CZS Stiftungsprofessur für Informatik und ihre Didaktik leitet.

\n\n END:VEVENT BEGIN:VEVENT UID:news1413@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221014T114957 DTSTART;TZID=Europe/Zurich:20221109T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Paolo Bonicatto (Univers ity of Warwick) DESCRIPTION:In the classical theory\, given a vector field $b$ on $\\mathbb R^d$\, one usually studies the transport/continuity equation drifted by $ b$ looking for solutions in the class of functions (with certain integrabi lity) or at most in the class of measures. In this seminar I will talk abo ut recent efforts\, motivated by the modelling of defects in plastic mater ials\, aimed at extending the previous theory to the case when the unknown is instead a family of k-currents in $\\mathbb R^d$\, i.e. generalised $k $-dimensional surfaces. The resulting equation involves the Lie derivative $L_b$ of currents in direction $b$ and reads $\\partial_t T_t + L_b T_t = 0$. In the first part of the talk I will briefly introduce this equation\ , with special attention to its space-time formulation. I will then shift the focus to some rectifiability questions and Rademacher-type results: gi ven a Lipschitz path of integral currents\, I will discuss the existence o f a “geometric derivative”\, namely a vector field advecting the curre nts. Joint work with G. Del Nin and F. Rindler (Warwick). X-ALT-DESC:In the classical theory\, given a vector field $b$ on $\\math bb R^d$\, one usually studies the transport/continuity equation drifted by $b$ looking for solutions in the class of functions (with certain integra bility) or at most in the class of measures. In this seminar I will talk a bout recent efforts\, motivated by the modelling of defects in plastic mat erials\, aimed at extending the previous theory to the case when the unkno wn is instead a family of k-currents in $\\mathbb R^d$\, i.e. generalised $k$-dimensional surfaces. The resulting equation involves the Lie derivati ve $L_b$ of currents in direction $b$ and reads $\\partial_t T_t + L_b T_t = 0$. In the first part of the talk I will briefly introduce this equatio n\, with special attention to its space-time formulation. I will then shif t the focus to some rectifiability questions and Rademacher-type results: given a Lipschitz path of integral currents\, I will discuss the existence of a “geometric derivative”\, namely a vector field advecting the cur rents. Joint work with G. Del Nin and F. Rindler (Warwick).

DTEND;TZID=Europe/Zurich:20221109T160000 END:VEVENT BEGIN:VEVENT UID:news1406@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221025T180506 DTSTART;TZID=Europe/Zurich:20221107T121500 SUMMARY:Bernoullis Tafelrunde: Ioanna Motschan-Armen (Chalmers University o f Technology) DESCRIPTION:abstract [t3://file?uid=3273] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20221107T130000 END:VEVENT BEGIN:VEVENT UID:news1412@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20221021T141230 DTSTART;TZID=Europe/Zurich:20221104T110000 SUMMARY:Seminar in Numerical Analysis: Naomi Schneider (Universität Siegen ) DESCRIPTION:Both the approximation of the gravitational potential via the d ownward continuation of satellite data and of wave velocities via the trav el time tomography using earthquake data are geoscientific ill- posed inve rse problems. To monitor certain aspects of the system Earth\, like the ma ss transport or its geomagnetic field\, it is\, however\, important to tac kle these challenges. Traditionally\, an approximation of such a linear(iz ed) inverse problem is obtained in one\, a-priori chosen basis system: eit her a global one\, e.g. spherical harmonics or polynomials on the ball\, o r a local one\, e.g. radial basis functions and wavelets on the sphere or finite elements on the ball. In the Geomathematics Group Siegen\, we devel oped methods that enable us to combine different types of trial functions for such an approximation. The idea is to make the most of the benefits of different types of available trial functions. The algorithms are called t he (Learning) Inverse Problem Matching Pursuits (LIPMPs). They construct a n approximation iteratively from an intentionally overcomplete set of tria l functions\, the dictionary\, such that the Tikhonov functional is reduce d. Due to the learning add-on\, the dictionary can very well be infinite. Moreover\, the computational costs are usually decreased. In this talk\, w e give details on the LIPMPs and show some current numerical results.\\r\\ nFor further information about the seminar\, please visit this webpage [t3 ://page?uid=1115]. X-ALT-DESC:Both the approximation of the gravitational potential via the
downward continuation of satellite data and of wave velocities via the tr
avel time tomography using earthquake data are geoscientific ill- posed in
verse problems. To monitor certain aspects of the system Earth\, like the
mass transport or its geomagnetic field\, it is\, however\, important to t
ackle these challenges.

Traditionally\, an approximation of such a l
inear(ized) inverse problem is obtained in one\, a-priori chosen basis sys
tem: either a global one\, e.g. spherical harmonics or polynomials on the
ball\, or a local one\, e.g. radial basis functions and wavelets on the sp
here or finite elements on the ball.

In the Geomathematics Group Sie
gen\, we developed methods that enable us to combine different types of tr
ial functions for such an approximation. The idea is to make the most of t
he benefits of different types of available trial functions. The algorithm
s are called the (Learning) Inverse Problem Matching Pursuits (LIPMPs). Th
ey construct an approximation iteratively from an intentionally overcomple
te set of trial functions\, the dictionary\, such that the Tikhonov functi
onal is reduced. Due to the learning add-on\, the dictionary can very well
be infinite. Moreover\, the computational costs are usually decreased.

In this talk\, we give details on the LIPMPs and show some current num
erical results.

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20221104T120000 END:VEVENT BEGIN:VEVENT UID:news1398@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220906T130330 DTSTART;TZID=Europe/Zurich:20221031T183000 SUMMARY:Wellen – mehr als Schönheit und Energie DESCRIPTION:We are surrounded by waves all the time\, even if we can only p erceive some of them: water waves\, sound waves\, earthquake waves\, light . Waves are not only omnipresent in our lives\, they are also used for a v ariety of purposes - be it for communication\, when looking at the earth o r into space.\\r\\nFor more information about the lecture series and regis tration please visit the website of the Volkshochschule Beider Basel [http s://www.vhsbb.ch/kursprogramm/mathematik-physik-technik-232833/wellen--meh r-als-schoenheit-und-energie-294005]. X-ALT-DESC:We are surrounded by waves all the time\, even if we can only perceive some of them: water waves\, sound waves\, earthquake waves\, lig ht. Waves are not only omnipresent in our lives\, they are also used for a variety of purposes - be it for communication\, when looking at the earth or into space.

\nFor more information about the lecture series and
registration please visit the **website of the Volkshochschule Beider Basel**.

**The Euler Commission has been publishing the works an
d correspondence of the mathematician Leonhard Euler (1707–1783) for mor
e than a hundred years. The publication of the last printed volume is cele
brated with an international symposium.**

To mark the compl etion of the printed edition of Opera Omnia\, the Bernoulli-Euler Society\ , together with the SCNAT Mathematics\, Astronomy and Physics Platform\, i s organizing an international symposium on October 29\, 2022 in Basel.At t he same time\, this is also the transition to a new phase: All works\, let ters and notebooks by Euler\, the Bernoulli and their environment are to b e presented online and freely accessible on a modern digital platform.

\n**Symposium on the scientific work of Leonhard Euler**\n

- 2.30 p.m.: Prof. Dr. Umberto Bottazzini (Università d egli Studi di Milano): «Elastica\, Lemnicate and Euler's Addition Theorem for Elliptic Integrals»
- 3.30 p.m.: Prof. Dr. Jesp er Lützen (University of Copenhagen): "Euler's general Analysis versus Ap plications"
- 4.30 p.m.: Coffee break

In th e run-up to the symposium\, there will also be an anniversary celebration to mark the end of the printed Euler edi tion on October 28th.

DTEND;TZID=Europe/Zurich:20221029T180000 END:VEVENT BEGIN:VEVENT UID:news1384@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220909T081907 DTSTART;TZID=Europe/Zurich:20221028T170000 SUMMARY:EULER - BERNOULLI: yesterday\, today\, tomorrow DESCRIPTION:The Euler Commission has been publishing the works and correspo ndence of the mathematician Leonhard Euler (1707–1783) for more than a h undred years. The publication of the last printed volume is celebrated wit h a ceremony.\\r\\nAt the end of the printed edition of the Opera Omnia\, the Bernoulli-Euler Society\, together with the SCNAT Mathematics\, Astron omy and Physics platform\, is organizing an anniversary celebration on Oct ober 28th and 29th\, 2022 in Basel.At the same time\, this is also the tra nsition to a new phase: All works\, letters and notebooks by Euler\, the B ernoulli and their environment are to be presented online and freely acces sible on a modern digital platform.\\r\\nProgram\\r\\nFriday\, October 28t h\\r\\nAt the Aula of Kollegienhaus\, Petersplatz 1\\r\\n 5 p.m.: Greetin gs from Prof. Dr. Andrea Schenker-Wicki\, Rector of the University of Base l\; Prof. Dr. Marcel Tanner\, President of the Swiss Academies of Arts and Sciences\; Prof. Dr. Matthias Egger\, President of the Board of Trustees of the Swiss National Science Foundation 5.30 p.m.: Lecture by Prof. Dr. Günter Ziegler\, President of Freie Universität Berlin: “Mathematics i s a broad field. Euler as universalist» 6:30 p.m.: Aperitif and vernissa ge of volume II 27 on celestial mechanics and presentation of the Euler co mic \\r\\nSaturday\, October 29th\\r\\nAt Grosser Hörsaal\, Alte Universi tät\, Rheinsprung 9\\r\\n 9 a.m.: Door is open\, coffee and tea 10 a.m. : Prof. Dr. Hans-Christoph Im Hof (Basel): «Die Edition der Werke Leonhar d Eulers»\, Prof. Dr. Andreas Kleinert (Halle): «Von den Petersburger Ma nuskripten zur Series IVA der Opera omnia. Zur Geschichte der Euler-Briefe dition» 11:30 a.m.: PD Dr. Rita Gautschy (Basel) und Prof. Dr. Gerd Gras shoff (Berlin): «Opera-Bernoulli-Euler.digital»\, with demonstrations (p lease bring your own notebook!) \\r\\nInternational Symposium\\r\\nIn addi tion to the anniversary celebration\, there will also be an international symposium [https://www.unibas.ch/de/Aktuell/Veranstaltungen.html?id=29158c 19-1bf2-4c4a-8d69-09db0b22d1ea] on October 28th to conclude the printed Eu ler edition.\\r\\nWebsite of the Bernoulli-Euler-Gesellschaft (BEG) [https ://bernoulli-euler-gesellschaft.ch/en] X-ALT-DESC:**The Euler Commission has been publishing the works an
d correspondence of the mathematician Leonhard Euler (1707–1783) for mor
e than a hundred years. The publication of the last printed volume is cele
brated with a ceremony.**

At the end of the printed edition of the Opera Omnia\, the Bernoulli-Euler Society\, together with the SCNA T Mathematics\, Astronomy and Physics platform\, is organizing an annivers ary celebration on October 28th and 29th\, 2022 in Basel.At the same time\ , this is also the transition to a new phase: All works\, letters and note books by Euler\, the Bernoulli and their environment are to be presented o nline and freely accessible on a modern digital platform.

\n**Friday\, October 28th**

**At the Aula of Kollegienhaus\, Petersplatz 1**

- <
li>5 p.m.: Greetings from Prof. Dr. Andrea Schenker-Wicki\, Rector o
f the University of Basel\; Prof. Dr. Marcel Tanner\, President of the Swi
ss Academies of Arts and Sciences\; Prof. Dr. Matthias Egger\, President o
f the Board of Trustees of the Swiss National Science Foundation
- 5.30 p.m.: Lecture by Prof. Dr. Günter Ziegler\, President of Freie Universität Berlin: “Mathematics is a broad field. Euler as un iversalist»
- 6:30 p.m.: Aperitif and vernissage of volume II 27 on celestial mechanics and presentation of the Euler comic

**Saturday\, October 29th**

In addition to the anniversary celebration\, there will also be an international symposi um on October 28th to conclude the printed Euler edition.

\nProgram:

\n- information about studying at D MI from Prof. Malte Helmert (Computer Science) and Prof. Philipp Habegger (Mathematics)
- getting to know the other first-semes ter students and the «higher semester»
- the Fachgr uppe of the DMI (FMI) introduces itself
- time for yo ur questions
- short tour with the Fachgruppe to the university buildings that are important to you
apéro on the mezzanine floor of the DMI

Prof. Malte Helmert welcomes the new master’s students in C omputer Science and

END:VEVENT BEGIN:VEVENT UID:news1378@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220621T094529 DTSTART;TZID=Europe/Zurich:20220711T080000 SUMMARY:21st IEEE International Symposium on Parallel and Distributed Compu ting DESCRIPTION:Program of the 21st IEEE ISPDC [https://ispdc2022.dmi.unibas.ch /program/]\\r\\nWebsite of the 21st IEEE ISPDC [https://ispdc2022.dmi.unib as.ch/] X-ALT-DESC:**Pr
ogram of the 21st IEEE ISPDC**

**Website of the 21st IEEE ISPDC**

The \;**International Congress of Mathematicians 20
22** \;(ICM 2022) will take place as a fully virtual event over
6–14 July 2022. Please note the following:

- Lecture s are scheduled to take place between 9:00–18:00 CEST every day.< /li>
- On 6 July\, the 2022 Fields Medalists and IMU Abacus Medal ist will give prize winner lectures live in Helsinki\, Finland. Admission to the lectures will be open to all who wish to attend. The lectures will also be streamed live.
- Participation is free of cha rge\, but registration is required.

Further announce ments will be made on the ICM 2022 webpage once available.

\n**If you would
like to attend\, please register here.**

We consider a system of $N$ interacting fermions initially co
nfined in a \;

volume

$\\Lambda$. We show that\, in the hi
gh-density regime and for zero-temperature \;

initial data

exhibiting a local semiclassical structure\, the solution of the many-bod
y \;

Schrödinger equation can be approximated by the solution o
f the nonlinear \;

Hartree equation\, up to errors that are smal
l\, for large density\, uniformly \;

in $N$ and $\\Lambda$. This
is joint work with M. Porta and B. Schlein.

\;

The Kompaneets equation describes energy transport in low-den
sity (or high \;temperature) plasmas where the dominant energy exchang
e mechanism is \;Compton scattering. The equation itself is a one dime
nsional non-linear \;parabolic equation with a diffusion coefficient t
hat vanishes at the

boundary. This degeneracy\, combined with the no
nlinearity causes an \;out-flux of photons with zero energy\, often in
terpreted as a Bose-Einstein \;condensate. This talk will describe sev
eral results about the long time \;behavior of these equations includi
ng convergence to equilibrium\,

persistence of the condensate\, suff
icient conditions under which it forms\, \;sufficient conditions under
which it doesn't form and a loss formula for \;the mass of the conden
sate.

I will present a recent result concerning global existence fo r the Kuramoto-Sivashinsky equation on the two-dimensional torus with one growing \;mode in each direction. The proof combines PDE techniques wi th a Lyapunov function argument for the growing modes. This is joint work with David Ambrose (Drexel University\, USA).

DTEND;TZID=Europe/Zurich:20220609T160000 END:VEVENT BEGIN:VEVENT UID:news1364@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220606T131917 DTSTART;TZID=Europe/Zurich:20220609T140000 SUMMARY:An afternoon of analysis talks: Giovanni Alberti (University of Pis a) DESCRIPTION:In this talk I will describe some result about the following el ementary problem\, of isoperimetric flavor: Given a set E in R^d with fini te volume\, is it possible to find an hyperplane P that cuts E in two part s with equal volume\, and such that the area of the cut (that is\, the int ersection of P and E) is of the expected order\, namely (vol(E))^{1−1/d} ? We can show that this question\, even in a stronger form\, has a positiv e answer if the dimension d is 3 or higher.But\, interestingly enough\, ou r proof breaks down completely in dimension d=2\, and we do not know the a nswer in this case (but we know that the answer is positive if we allow cu ts that are not exactly planar\, but close to planar). It turns out that this question has some interesting connection with the Kakeya problem. Thi s is a work in progress with Alan Chang (Princeton University). X-ALT-DESC:In this talk I will describe some result about the following
elementary problem\, of isoperimetric flavor:

Given a set E in R^d w
ith finite volume\, is it possible to find an hyperplane P that cuts E in
two parts with equal volume\, and such that the area of the cut (that is\,
the intersection of P and E) is of the expected order\, namely (vol(E))^{
1−1/d}?

We can show that this question\, even in a stronger form\,
has a positive answer if the dimension d is 3 or higher.But\, interesting
ly enough\, our proof breaks down completely in dimension d=2\, and we do
not know the answer in this case (but we know that the answer is positive
if we allow cuts that are not exactly planar\, but close to planar). \
;It turns out that this question has some interesting connection with the
Kakeya problem.

This is a work in progress with Alan Chang (Princeto
n University).

In this talk\, we will discuss the proof of the unb ounded denominators conjecture on Fourier coefficients of SL_2(Z)-modular forms\, and the proof of irrationality of 2-adic zeta value at 5. Both pro ofs use an arithmetic holonomicity theorem\, which can be viewed as a refi nement of André’s algebraicity criterion. If time permits\, we will giv e a proof of the arithmetic holonomicity theorem via the slope method a la Bost.

\nThis is joint work with Frank Calegari and Vessel in Dimitrov.

\nFor further information about the seminar\, please vi sit this webpage.

DTEND;TZID=Europe/Zurich:20220526T180000 END:VEVENT BEGIN:VEVENT UID:news1356@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220429T093028 DTSTART;TZID=Europe/Zurich:20220526T100000 SUMMARY:FANTASY BASEL 2022 DESCRIPTION:The Department of Mathematics and Computer Science will be pres ent again at this year's FANTASY Basel.\\r\\nFurther information can be fo und here:\\r\\nWebsite FANTASY Basel [https://www.fantasybasel.ch/en/] X-ALT-DESC:The Department of Mathematics and Computer Science will be pr esent again at this year's FANTASY Basel.

\nFurther information can be found here:

\n\n\n DTEND;TZID=Europe/Zurich:20220528T180000 END:VEVENT BEGIN:VEVENT UID:news1353@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220504T163350 DTSTART;TZID=Europe/Zurich:20220525T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Franck Sueur (Institut d e Mathématiques de Bordeaux) DESCRIPTION:This talk is devoted to the 2D incompressible Euler system in p resence of sources and sinks. This model dates back to Viktor Yudovich in the sixties and is an interesting example of nonlinear open system which h as been widely used in controllability theory within the scope of smooth s olutions. In this talk we will review how the classical issues of existenc e and uniqueness of weak solutions are challenged by the presence of incom ing and exiting vorticity. This talk is based on joint works with Marco Bravin and Florent Noisette. X-ALT-DESC:This talk is devoted to the 2D incompressible Euler system in presence of sources and sinks. This model dates back to Viktor Yudovich i n the sixties and is an interesting example of nonlinear open system which has been widely used in controllability theory within the scope of smooth solutions. In this talk we will review how the classical issues of existe nce and uniqueness of weak solutions are challenged by the presence of inc oming and exiting vorticity. \;This talk is based on joint works with Marco Bravin and Florent Noisette. \;

DTEND;TZID=Europe/Zurich:20220525T160000 END:VEVENT BEGIN:VEVENT UID:news1349@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220516T145629 DTSTART;TZID=Europe/Zurich:20220523T121500 SUMMARY:Bernoullis Tafelrunde: Pascal Oswald (University of Basel) DESCRIPTION:Abstract [t3://file?uid=3183] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220523T130000 END:VEVENT BEGIN:VEVENT UID:news1358@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220429T084717 DTSTART;TZID=Europe/Zurich:20220520T180000 SUMMARY:Museums Night DESCRIPTION:The Department of Mathematics and Computer Science will be pres ent again at this year's Museums Night. Further information can be found h ere:\\r\\nWebsite Museums Night [https://museumsnacht.ch/en] X-ALT-DESC:The Department of Mathematics and Computer Science will be pr
esent again at this year's Museums Night.

Further information can be
found here:

Optimal control problems subject to constraints given by part
ial differential equations are a powerful tool for the improvement of many
tasks in science an technology. Classic optimization today is applicable
on various problems and tackling nonlinear equations and inclusion of box
constraints on the solutions is flexible. However\, especially for non-sta
tionary problems\, small perturbations along the trajectories can easily l
ead to large deviations in the desired solutions. Consequently\, optimalit
y may be lost just as easily.

On the other hand\, the linear-quadrat
ic regulator problem in system theory is an approach to make a dynamical s
ystem react to perturbation via feedback controls that can be expressed by
the solutions of matrix Riccati equations. It’s applicability is limite
d by the linearity of the dynamical system and the efficient solvability o
f the quadratic matrix equation.

In this talk\, we discuss how certa
in classes of non-stationary PDEs can be reformulated (after spatial semi-
discretization) into structured linear dynamical systems that allow the Ri
ccati feedback to be computed. This allows us to combine both approaches a
nd thus steer solutions of perturbed PDEs back to the optimized trajectori
es. The key to efficient solvers for the Riccati equations is the usage of
the specific structure in the problems and the fact that the Riccati solu
tions usually feature a strong singular value decay\, and thus good low-ra
nk approximability.

For further information about the seminar\, pl ease visit this webpage.

DTEND;TZID=Europe/Zurich:20220520T120000 END:VEVENT BEGIN:VEVENT UID:news1370@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220519T114626 DTSTART;TZID=Europe/Zurich:20220519T170000 SUMMARY:Number Theory Web Seminar: Jeffrey Vaaler (University of Texas at A ustin) DESCRIPTION:The abstract of the talk is here [https://drive.google.com/file /d/1VDQLDlcC3IDEMduR6H-X9Rf0jRxSZ_J-/view] available.\\r\\nFor further inf ormation about the seminar\, please visit this webpage [https://www.ntwebs eminar.org/]. X-ALT-DESC:The abstract of the talk is here available.

\n< p>For further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20220519T180000 END:VEVENT BEGIN:VEVENT UID:news1354@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220508T162554 DTSTART;TZID=Europe/Zurich:20220518T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Banhirup Sengupta (Unive rsitat Autònoma de Barcelona) DESCRIPTION:In this talk I am going to provide a pointwise characterisation of nearly incompressible vector fields with bounded curl. Euler vector fi elds fall in this class. I will also talk about rotational properties of E uler flows and nonlinear transport equations involving Cauchy Kernel in th e plane. This is based on joint works with Albert Clop (Barcelona) and Lau ri Hitruhin (Helsinki). X-ALT-DESC:In this talk I am going to provide a pointwise characterisati on of nearly incompressible vector fields with bounded curl. Euler vector fields fall in this class. I will also talk about rotational properties of Euler flows and nonlinear transport equations involving Cauchy Kernel in the plane. This is based on joint works with Albert Clop (Barcelona) and L auri Hitruhin (Helsinki).

DTEND;TZID=Europe/Zurich:20220518T160000 END:VEVENT BEGIN:VEVENT UID:news1332@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220505T171325 DTSTART;TZID=Europe/Zurich:20220516T121500 SUMMARY:Bernoullis Tafelrunde: Nafie Tairi (University of Bern) DESCRIPTION:Abstract [t3://file?uid=3171] X-ALT-DESC:\n\n DTEND;TZID=Europe/Zurich:20220516T130000 END:VEVENT BEGIN:VEVENT UID:news1363@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220502T112414 DTSTART;TZID=Europe/Zurich:20220512T170000 SUMMARY:Number Theory Web Seminar: Robert Charles Vaughan (Pennsylvania St ate University) DESCRIPTION:The abstract of the talk is here [https://drive.google.com/file /d/17K_PLvpAkfZ3S5nw2yOWQKC18MgLl2rC/view] available:\\r\\nFor further inf ormation about the seminar\, please visit this webpage [https://www.ntwebs eminar.org/]. X-ALT-DESC:The abstract of the talk is here available:

\n< p>For further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20220512T180000 END:VEVENT BEGIN:VEVENT UID:news1361@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220429T112842 DTSTART;TZID=Europe/Zurich:20220510T160000 SUMMARY:The AI Gene in the DNA of Digitalization DESCRIPTION:Nataliia Rzhevska\, PhD\, is lecturer at the Pereiaslav-Khmelny tskyi Hryhorii Skovoroda State Pedagogical University\, Ukraine\, and vice rector at the University of Artificial Intelligence and Digitalization in Kiev\, Ukraine. As an expert in Neuropedagogy and AI\, Nataliia is workin g on the subjects of cognitive future for students while supporting teache rs at university level.\\r\\nIn her work\, she aims at strengthening civil society structures and empowerment in the areas of research and gender eq uality as well as information and knowledge management. Nataliia is also C IO of VideoWiki\, a collaborative platform for learners and educators to s ecure earning continuity in times of restrictions and beyond.\\r\\nThe eve nt will be held on on Zoom. If you are interested\, please contact us\, to get the link to join (info.we-are-cs@unibas.ch [mailto:info.we-are-cs@uni bas.ch]). X-ALT-DESC:Nataliia Rzhevska\, PhD\, is lecturer at the Pereiaslav-Khmel
nytskyi Hryhorii Skovoroda State Pedagogical University\, Ukraine\, and vi
ce rector at the University of Artificial Intelligence and Digitalization
in Kiev\, Ukraine. As an expert in Neuropedagogy and AI\, Nataliia is work
ing on the subjects of

cognitive future for students while supportin
g teachers at university level.

In her work\, she aims at strength ening civil society structures and empowerment in the areas of research an d gender equality as well as information and knowledge management. Natalii a is also CIO of VideoWiki\, a collaborative platform for learners and edu cators to secure earning continuity in times of restrictions and beyond.\n

The event will be held on on Zoom. If you are interested\, please c ontact us\, to get the link to join (info.we-are-cs@unibas.ch).

END:VEVENT BEGIN:VEVENT UID:news1320@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220421T100545 DTSTART;TZID=Europe/Zurich:20220509T121500 SUMMARY:Bernoullis Tafelrunde: Elias Polak (Université de Genève) DESCRIPTION:abstract [t3://file?uid=3166] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220509T130000 END:VEVENT BEGIN:VEVENT UID:news1306@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220502T111049 DTSTART;TZID=Europe/Zurich:20220505T170000 SUMMARY:Number Theory Web Seminar: Levent Alpöge (Harvard University) DESCRIPTION:It's easy that 0% of integers are the sum of two integral cubes (allowing opposite signs!).\\r\\nI will explain joint work with Bhargava and Shnidman in which we show:\\r\\n1. At least a sixth of integers are no t the sum of two rational cubes\,\\r\\nand\\r\\n2. At least a sixth of odd integers are the sum of two rational cubes!\\r\\n(--- with 2. relying on new 2-converse results of Burungale-Skinner.)\\r\\nThe basic principle is that "there aren't even enough 2-Selmer elements to go around" to contradi ct e.g. 1.\, and we show this by using the circle method "inside" the usua l geometry of numbers argument applied to a particular coregular represent ation. Even then the resulting constant isn't small enough to conclude 1.\ , so we use the clean form of root numbers in the family x^3 + y^3 = n and the p-parity theorem of Nekovar/Dokchitser-Dokchitser to succeed.\\r\\nFo r further information about the seminar\, please visit this webpage [https ://www.ntwebseminar.org/]. X-ALT-DESC:It's easy that 0% of integers are the sum of two in tegral cubes (allowing opposite signs!).

\nI will explain joint work with Bhargava and Shnidman in which we show:

\n1. At least a sixth of integers are not the sum of two rational cubes\,

\nand

\n2. At least a sixth of odd integers are the sum of two rational cu bes!

\n(--- with 2. relying on new 2-converse results of Burungale-S kinner.)

\nThe basic principle is that "there aren't even enough 2-Selmer elements to go around" to contradict e.g. 1.\, and we show this by using the circle method "inside" the usual geometry of numbers ar gument applied to a particular coregular representation. Even then the res ulting constant isn't small enough to conclude 1.\, so we use the clean fo rm of root numbers in the family x^3 + y^3 = n and the p-parity theorem of Nekovar/Dokchitser-Dokchitser to succeed.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220505T180000 END:VEVENT BEGIN:VEVENT UID:news1327@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220422T115503 DTSTART;TZID=Europe/Zurich:20220504T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Gabriel Sattig (Universi tät Leipzig) DESCRIPTION:It was shown by Modena and Székelyhidi that weak solutions to the incompressible transport equation may be not unique\, even if the tr ansporting field is Sobolev\, thus admitting a unique regular Lagrangian flow. In this talk I will present a recent result saying that non-Lagrang ian solutions are generic in the Baire category sense. Joint work with L . Székelyhidi. X-ALT-DESC:It was shown by Modena and Székelyhidi that weak solutions t o the \;incompressible transport equation may be not unique\, even if the \;transporting field is Sobolev\, thus admitting a unique regular& nbsp\;Lagrangian flow. \;In this talk I will present a recent result s aying that non-Lagrangian \;solutions are generic in the Baire categor y sense. \;Joint work with L. Székelyhidi.

DTEND;TZID=Europe/Zurich:20220504T160000 END:VEVENT BEGIN:VEVENT UID:news1331@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220429T140038 DTSTART;TZID=Europe/Zurich:20220502T121500 SUMMARY:Bernoullis Tafelrunde: Florian Lanz (University of Basel) DESCRIPTION:abstract [t3://file?uid=3170] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220502T130000 END:VEVENT BEGIN:VEVENT UID:news1307@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220425T100745 DTSTART;TZID=Europe/Zurich:20220428T170000 SUMMARY:Number Theory Web Seminar: Andrew Granville (Université de Montré al) DESCRIPTION:In 1878\, in the first volume of the first mathematics journal published in the US\, Edouard Lucas wrote 88 pages (in French) on linear r ecurrence sequences\, placing Fibonacci numbers and other linear recurrenc e sequences into a broader context. He examined their behaviour locally as well as globally\, and asked several questions that influenced much resea rch in the century and a half to come.\\r\\nIn a sequence of papers in the 1930s\, Marshall Hall further developed several of Lucas' themes\, includ ing studying and trying to classify third order linear divisibility sequen ces\; that is\, linear recurrences like the Fibonacci numbers which have t he additional property that $F_m$ divides $F_n$ whenever $m$ divides $n$. Because of many special cases\, Hall was unable to even conjecture what a general theorem should look like\, and despite developments over the years by various authors\, such as Lehmer\, Morgan Ward\, van der Poorten\, Bez ivin\, Petho\, Richard Guy\, Hugh Williams\,... with higher order linear d ivisibility sequences\, even the formulation of the classification has rem ained mysterious.\\r\\nIn this talk we present our ongoing efforts to clas sify all linear divisibility sequences\, the key new input coming from a w onderful application of the Schmidt/Schlickewei subspace theorem from the theory of diophantine approximation\, due to Corvaja and Zannier.\\r\\nFor further information about the seminar\, please visit this webpage [https: //www.ntwebseminar.org/]. X-ALT-DESC:In 1878\, in the first volume of the first mathemat ics journal published in the US\, Edouard Lucas wrote 88 pages (in French) on linear recurrence sequences\, placing Fibonacci numbers and other line ar recurrence sequences into a broader context. He examined their behaviou r locally as well as globally\, and asked several questions that influence d much research in the century and a half to come.

\nIn a sequence of papers in the 1930s\, Marshall Hall further developed several of Lucas' themes\, including studying and trying to classify third order l inear divisibility sequences\; that is\, linear recurrences like the Fibon acci numbers which have the additional property that $F_m$ divides $F_n$ w henever $m$ divides $n$. Because of many special cases\, Hall was unable t o even conjecture what a general theorem should look like\, and despite de velopments over the years by various authors\, such as Lehmer\, Morgan War d\, van der Poorten\, Bezivin\, Petho\, Richard Guy\, Hugh Williams\,... w ith higher order linear divisibility sequences\, even the formulation of t he classification has remained mysterious.

\nIn this talk we present our ongoing efforts to classify all linear divisibility sequenc es\, the key new input coming from a wonderful application of the Schmidt/ Schlickewei subspace theorem from the theory of diophantine approximation\ , due to Corvaja and Zannier.

\nFor further information about the se minar\, please visit this webpage< /a>.

DTEND;TZID=Europe/Zurich:20220428T180000 END:VEVENT BEGIN:VEVENT UID:news1355@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220411T160234 DTSTART;TZID=Europe/Zurich:20220428T170000 SUMMARY:Bernoulli Meets Industry: Novartis Institutes of Biomedical Researc h DESCRIPTION:Have you ever wondered what to do after your degree?\\r\\nWe in vite you to the new seminar “Bernoulli meets Industry”\, an evening ev ent where\\r\\nformer mathematicians talk about their current work\, follo wed by an apéro. \\r\\nflyer [t3://file?uid=3162] X-ALT-DESC:Have you ever wondered what to do after your degree?

\nWe invite you to the new seminar “Bernoulli meets Industry”\, an eveni ng event where

\nformer mathematicians talk about their current work \, followed by an apéro. \;

\n DTEND;TZID=Europe/Zurich:20220428T190000 END:VEVENT BEGIN:VEVENT UID:news1324@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220409T172448 DTSTART;TZID=Europe/Zurich:20220427T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Jaemin Park (University of Barcelona) DESCRIPTION:In this talk\, we study stationary solutions to the 2D incompre ssible Euler equations in the whole plane. It is well-known that any radia l vorticity is stationary. For compactly supported vorticity\, it is more difficult to see whether a stationary solution has to be radial. In the ca se where the vorticity is non-negative\, it has been shown that any statio nary solution has be radial. By allowing the vorticity to change the sign\ , we prove that there exist non-radial stationary patch-type solutions. We construct patch-type solutions whose kinetic energy is infinite or finite . For the finite energy case\, it turns out that a construction of a stati onary solution with compactly supported velocity is possible. X-ALT-DESC:In this talk\, we study stationary solutions to the 2D incomp ressible Euler equations in the whole plane. It is well-known that any rad ial vorticity is stationary. For compactly supported vorticity\, it is mor e difficult to see whether a stationary solution has to be radial. In the case where the vorticity is non-negative\, it has been shown that any stat ionary solution has be radial. By allowing the vorticity to change the sig n\, we prove that there exist non-radial stationary patch-type solutions. We construct patch-type solutions whose kinetic energy is infinite or fini te. For the finite energy case\, it turns out that a construction of a sta tionary solution with compactly supported velocity is possible.

DTEND;TZID=Europe/Zurich:20220427T160000 END:VEVENT BEGIN:VEVENT UID:news1330@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220411T102848 DTSTART;TZID=Europe/Zurich:20220425T121500 SUMMARY:Bernoullis Tafelrunde: Johan Ulander (CHALMERS\, Gothenburg) DESCRIPTION:Abstract [t3://file?uid=3161] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220425T130000 END:VEVENT BEGIN:VEVENT UID:news1351@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220419T163823 DTSTART;TZID=Europe/Zurich:20220422T110000 SUMMARY:Seminar in Numerical Analysis: Matthias Voigt (FernUni Schweiz) DESCRIPTION:We introduce a model reduction approach for linear time-invaria nt second-order systems based on positive real balanced truncation. Our me thod guarantees to preserve passivity of the reduced-order model as well a s the positive definiteness of the mass and stiffness matrices and admits an a priori gap metric error bound. Our construction of the second-order r educed model is based on the consideration of an internal symmetry structu re and the invariant zeros of the system and their sign-characteristics fo r which we derive a normal form. The results are available in [1].\\r\\n[1 ] I. Dorschky\, T. Reis\, and M. Voigt. Balanced truncation model reductio n for symmetric second order systems - a passivity-based approach. SIAM J. Matrix Anal. Appl.\, 42(4):1602--1635\, 2021.\\r\\nFor further informatio n about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:We introduce a model reduction approach for linear time-invar
iant second-order systems based on positive real balanced truncation.

Our method guarantees to preserve passivity of the reduced-order model a
s well as the positive definiteness of the mass and stiffness matrices and
admits an a priori gap metric error bound.

Our construction of the
second-order reduced model is based on the consideration of an internal sy
mmetry structure and the invariant zeros of the system and their sign-char
acteristics for which we derive a normal form.

The results are avail
able in [1].

[1] I. Dorschky\, T. Reis\, and M. Voigt. Balanced tr uncation model reduction for symmetric second order systems - a passivity- based approach. SIAM J. Matrix Anal. Appl.\, 42(4):1602--1635\, 2021.

\ nFor further information about the seminar\, please visit this webpage .

DTEND;TZID=Europe/Zurich:20220422T120000 END:VEVENT BEGIN:VEVENT UID:news1304@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220325T101357 DTSTART;TZID=Europe/Zurich:20220421T170000 SUMMARY:Number Theory Web Seminar: Joni Teräväinen (University of Turku) DESCRIPTION:I will discuss the short interval behaviour of the von Mangoldt and Möbius functions twisted by exponentials. I will in particular menti on new results on sums of these functions twisted by polynomial exponentia l phases\, or even more general nilsequence phases. I will also discuss co nnections to Chowla's conjecture. This is based on joint works with Kaisa Matomäki\, Maksym Radziwiłł\, Xuancheng Shao\, Terence Tao and Tamar Zi egler.\\r\\nFor further information about the seminar\, please visit this webpage [https://www.ntwebseminar.org/]. X-ALT-DESC:I will discuss the short interval behaviour of the von Mangoldt and Möbius functions twisted by exponentials. I will in part icular mention new results on sums of these functions twisted by polynomia l exponential phases\, or even more general nilsequence phases. I will als o discuss connections to Chowla's conjecture. This is based on joint works with Kaisa Matomäki\, Maksym Radziwiłł\, Xuancheng Shao\, Terence Tao and Tamar Ziegler.

\nFor further information about the seminar\, ple ase visit this webpage.

DTEND;TZID=Europe/Zurich:20220421T180000 END:VEVENT BEGIN:VEVENT UID:news1303@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220411T135326 DTSTART;TZID=Europe/Zurich:20220414T170000 SUMMARY:Number Theory Web Seminar: Ram Murty (Queen's University) DESCRIPTION:There is a probability distribution attached to the Riemann zet a function which allows one to formulate the Riemann hypothesis in terms o f the cumulants of this distribution and is due to Biane\, Pitman and Yor. The cumulants can be related to generalized Euler-Stieltjes constants and to Li's criterion for the Riemann hypothesis. We will discuss these resul ts and present some new results related to this theme.\\r\\nFor further in formation about the seminar\, please visit this webpage [https://www.ntweb seminar.org/]. X-ALT-DESC:There is a probability distribution attached to the Riemann zeta function which allows one to formulate the Riemann hypothesi s in terms of the cumulants of this distribution and is due to Biane\, Pit man and Yor. The cumulants can be related to generalized Euler-Stieltjes c onstants and to Li's criterion for the Riemann hypothesis. We will discuss these results and present some new results related to this theme.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220414T180000 END:VEVENT BEGIN:VEVENT UID:news1319@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220404T091216 DTSTART;TZID=Europe/Zurich:20220411T121500 SUMMARY:Bernoullis Tafelrunde: Flavio Salizzoni (Université de Neuchâtel) DESCRIPTION:Abstract [t3://file?uid=3141] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220411T130000 END:VEVENT BEGIN:VEVENT UID:news1333@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220315T174614 DTSTART;TZID=Europe/Zurich:20220408T110000 SUMMARY:Seminar in Numerical Analysis: Ralf Hiptmair (ETH Zürich) DESCRIPTION:We consider scalar-valued shape functionals on sets of shapes w hich are small perturbations of a reference shape. The shapes are describe d by parameterizations and their closeness is induced by a Hilbert space s tructure on the parameter domain. We justify a heuristic for finding the b est low-dimensional parameter subspace with respect to uniformly approxima ting a given shape functional. We also propose an adaptive algorithm for a chieving a prescribed accuracy when representing the shape functional with a small number of shape parameters.\\r\\nFor further information about th e seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:We consider scalar-valued shape functionals on sets of shapes which are small perturbations of a reference shape. The shapes are descri bed by parameterizations and their closeness is induced by a Hilbert space structure on the parameter domain. We justify a heuristic for finding the best low-dimensional parameter subspace with respect to uniformly approxi mating a given shape functional. We also propose an adaptive algorithm for achieving a prescribed accuracy when representing the shape functional wi th a small number of shape parameters.

\nFor further information abo ut the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220408T120000 END:VEVENT BEGIN:VEVENT UID:news1302@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220325T101305 DTSTART;TZID=Europe/Zurich:20220407T170000 SUMMARY:Number Theory Web Seminar: Ana Caraiani (Imperial College London) DESCRIPTION:Shimura varieties are certain highly symmetric algebraic variet ies that generalise modular curves and that play an important role in the Langlands program. In this talk\, I will survey recent vanishing conjectur es and results about the cohomology of Shimura varieties with torsion coef ficients\, under both local and global representation-theoretic conditions . I will illustrate the geometric ingredients needed to establish these re sults using the toy model of the modular curve. I will also mention severa l applications\, including to (potential) modularity over CM fields.\\r\\n For further information about the seminar\, please visit this webpage [htt ps://www.ntwebseminar.org/]. X-ALT-DESC:Shimura varieties are certain highly symmetric alge braic varieties that generalise modular curves and that play an important role in the Langlands program. In this talk\, I will survey recent vanishi ng conjectures and results about the cohomology of Shimura varieties with torsion coefficients\, under both local and global representation-theoreti c conditions. I will illustrate the geometric ingredients needed to establ ish these results using the toy model of the modular curve. I will also me ntion several applications\, including to (potential) modularity over CM f ields.

\nFor further information about the seminar\, please visit th is webpage.

DTEND;TZID=Europe/Zurich:20220407T180000 END:VEVENT BEGIN:VEVENT UID:news1321@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220214T151002 DTSTART;TZID=Europe/Zurich:20220406T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Dr. Eliot Pacherie (NYU Abu Dhabi) DESCRIPTION:tba X-ALT-DESC:tba

DTEND;TZID=Europe/Zurich:20220406T160000 END:VEVENT BEGIN:VEVENT UID:news1318@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220326T140608 DTSTART;TZID=Europe/Zurich:20220404T121500 SUMMARY:Bernoullis Tafelrunde: Paula Truöl (ETH Zürich) DESCRIPTION:Abstract [t3://file?uid=3132] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220404T130000 END:VEVENT BEGIN:VEVENT UID:news1334@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220325T150305 DTSTART;TZID=Europe/Zurich:20220401T110000 SUMMARY:Seminar in Numerical Analysis: Johannes Pfefferer (Technische Unive rsität München) DESCRIPTION:Many areas of science and engineering involve optimal control o f processes that are modeled through partial differential equations. This talk will introduce the theoretical foundation and numerical methods based on finite elements for solving PDE constrained optimal control problems. We will discuss different discretization concepts and corresponding discre tization error estimates. The discussion will include the consideration of optimal control problems with control constraints as well as with state c onstraints.\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Many areas of science and engineering involve optimal control of processes that are modeled through partial differential equations. Thi s talk will introduce the theoretical foundation and numerical methods bas ed on finite elements for solving PDE constrained optimal control problems . We will discuss different discretization concepts and corresponding disc retization error estimates. The discussion will include the consideration of optimal control problems with control constraints as well as with state constraints.

\nFor further information about the seminar\, please v isit this webpage.

DTEND;TZID=Europe/Zurich:20220401T120000 END:VEVENT BEGIN:VEVENT UID:news1339@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220325T101040 DTSTART;TZID=Europe/Zurich:20220331T170000 SUMMARY:Number Theory Web Seminar: William Chen (Institute for Advanced Stu dy) DESCRIPTION:In this talk we will show that the integral points of the Marko ff equation x^2 + y^2 + z^2 - xyz = 0 surject onto its F_p-points for all but finitely many primes p. This essentially resolves a conjecture of Bour gain\, Gamburd\, and Sarnak\, and a question of Frobenius from 1913. The p roof relates the question to the classical problem of classifying the conn ected components of the Hurwitz moduli spaces H(g\,n) classifying finite c overs of genus g curves with n branch points. Over a century ago\, Clebsch and Hurwitz established connectivity for the subspace classifying simply branched covers of the projective line\, which led to the first proof of t he irreducibility of the moduli space of curves of a given genus. More rec ently\, the work of Dunfield-Thurston and Conway-Parker establish connecti vity in certain situations where the monodromy group is fixed and either g or n are allowed to be large\, which has been applied to study Cohen-Lens tra heuristics over function fields. In the case where (g\,n) are fixed an d the monodromy group is allowed to vary\, far less is known. In our case we study SL(2\,p)-covers of elliptic curves\, only branched over the origi n\, and establish connectivity\, for all sufficiently large p\, of the sub space classifying those covers with ramification indices 2p. The proof bui lds upon asymptotic results of Bourgain\, Gamburd\, and Sarnak\, the key n ew ingredient being a divisibility result on the degree of a certain forge tful map between moduli spaces\, which provides enough rigidity to bootstr ap their asymptotics to a result for all sufficiently large p.\\r\\nFor fu rther information about the seminar\, please visit this webpage [https://w ww.ntwebseminar.org/]. X-ALT-DESC:In this talk we will show that the integral points of the Markoff equation x^2 + y^2 + z^2 - xyz = 0 surject onto its F_p-poi nts for all but finitely many primes p. This essentially resolves a conjec ture of Bourgain\, Gamburd\, and Sarnak\, and a question of Frobenius from 1913. The proof relates the question to the classical problem of classify ing the connected components of the Hurwitz moduli spaces H(g\,n) classify ing finite covers of genus g curves with n branch points. Over a century a go\, Clebsch and Hurwitz established connectivity for the subspace classif ying simply branched covers of the projective line\, which led to the firs t proof of the irreducibility of the moduli space of curves of a given gen us. More recently\, the work of Dunfield-Thurston and Conway-Parker establ ish connectivity in certain situations where the monodromy group is fixed and either g or n are allowed to be large\, which has been applied to stud y Cohen-Lenstra heuristics over function fields. In the case where (g\,n) are fixed and the monodromy group is allowed to vary\, far less is known. In our case we study SL(2\,p)-covers of elliptic curves\, only branched ov er the origin\, and establish connectivity\, for all sufficiently large p\ , of the subspace classifying those covers with ramification indices 2p. T he proof builds upon asymptotic results of Bourgain\, Gamburd\, and Sarnak \, the key new ingredient being a divisibility result on the degree of a c ertain forgetful map between moduli spaces\, which provides enough rigidit y to bootstrap their asymptotics to a result for all sufficiently large p.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220331T180000 END:VEVENT BEGIN:VEVENT UID:news1317@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220321T101851 DTSTART;TZID=Europe/Zurich:20220328T121500 SUMMARY:Bernoullis Tafelrunde: Oussama Al Jarroudi (Universität Basel) DESCRIPTION:abstract [t3://file?uid=3130] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220328T130000 END:VEVENT BEGIN:VEVENT UID:news1340@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220321T111220 DTSTART;TZID=Europe/Zurich:20220325T110000 SUMMARY:Seminar in Numerical Analysis: Stepan Shakhno (Ivan Franko National University of Lviv) DESCRIPTION:In this talk\, one- and two-step methods for solving nonlinear equations with nondifferentiable operators are proposed. These methods are based on two methods: using derivatives and using divided differences. Th e local and semi-local convergence of the proposed methods is studied and the order of their convergence is established. We apply our results to the numerical solving of systems of nonlinear equations.\\r\\nFor further inf ormation about the seminar\, please visit this webpage [t3://page?uid=1115 ]. X-ALT-DESC:In this talk\, one- and two-step methods for solving nonlinea r equations with nondifferentiable operators are proposed. These methods a re based on two methods: using derivatives and using divided differences.< br /> The local and semi-local convergence of the proposed methods is stud ied and the order of their convergence is established. We apply our result s to the numerical solving of systems of nonlinear equations.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220325T120000 END:VEVENT BEGIN:VEVENT UID:news1301@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220317T094916 DTSTART;TZID=Europe/Zurich:20220324T170000 SUMMARY:Number Theory Web Seminar: Winnie Li (Pennsylvania State University ) DESCRIPTION:The theme of this survey talk is zeta functions which count clo sed geodesics on objects arising from real and p-adic groups. Our focus is on PGL(n). For PGL(2)\, these are the Selberg zeta function for compact q uotients of the upper half-plane and the Ihara zeta function for finite re gular graphs. We shall explain the identities satisfied by these zeta func tions\, which show interconnections between combinatorics\, group theory a nd number theory. Comparisons will be made for zeta identities from differ ent background. Like the Riemann zeta function\, the analytic behavior of a group based zeta function governs the distribution of the prime geodesic s in its definition.\\r\\nFor further information about the seminar\, plea se visit this webpage [https://www.ntwebseminar.org/]. X-ALT-DESC:The theme of this survey talk is zeta functions whi ch count closed geodesics on objects arising from real and p-adic groups. Our focus is on PGL(n). For PGL(2)\, these are the Selberg zeta function f or compact quotients of the upper half-plane and the Ihara zeta function f or finite regular graphs. We shall explain the identities satisfied by the se zeta functions\, which show interconnections between combinatorics\, gr oup theory and number theory. Comparisons will be made for zeta identities from different background. Like the Riemann zeta function\, the analytic behavior of a group based zeta function governs the distribution of the pr ime geodesics in its definition.

\nFor further information about the seminar\, please visit this webpa ge.

DTEND;TZID=Europe/Zurich:20220324T180000 END:VEVENT BEGIN:VEVENT UID:news1313@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220320T140750 DTSTART;TZID=Europe/Zurich:20220323T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Dr. Raphael Winter (ENS Lyon) DESCRIPTION:Following the pioneering work of Lanford\, a rigorous theory ha s been developed for the validation of the Boltzmann equation in the low-d ensity Grad scaling. In the physics literature\, an important issue are th e corrections to the equation for small but positive volume fraction. The first order correction to the Boltzmann equation is conjectured to be give n by the so-called Choh-Uhlenbeck equation\, which is of the form\\r\\n∂ tfϵ=Qϵ\,BE(fϵ\,fϵ)+ϵQϵ\,CU(fϵ\,fϵ\,fϵ).\\r\\n Here Qϵ\,BE is the Boltzmann-Enskog operator\, and the Choh-Uhlenbeck operator Qϵ\,CU is an explicit cubic operator. This operator accounts for the formation of dyna mic microscopic correlations between three particles. In this work\, we pr ove rigorously that the Choh-Uhlenbeck equation gives the first order corr ection to the Boltzmann equation in the Grad-scaling. This is a joint work with Sergio Simonella. X-ALT-DESC:Following the pioneering work of Lanford\, a rigorous theory has been developed for the validation of the Boltzmann equation in the low -density Grad scaling. In the physics literature\, an important issue are the corrections to the equation for small but positive volume fraction. Th e first order correction to the Boltzmann equation is conjectured to be gi ven by the so-called Choh-Uhlenbeck equation\, which is of the form

\n< p>∂tf

Here Qϵ\,BE is the Boltzmann-Enskog operator\, and the C
hoh-Uhlenbeck operator Qϵ\,CU is an explicit cubic operator. This operator
accounts for the formation of dynamic microscopic correlations between th
ree particles. In this work\, we prove rigorously that the Choh-Uhlenbeck
equation gives the first order correction to the Boltzmann equation in the
Grad-scaling. This is a joint work with Sergio Simonella.

We consider the computational complexity of approximating ell
iptic PDEs with random coefficients by sparse product polynomial expansion
s. Except for special cases (for instance\, when the spatial discretisatio
n limits the achievable overall convergence rate)\, previous approaches fo
r \;*a posteriori* \;selection of polynomial terms and corr
esponding spatial discretizations do not guarantee optimal complexity in t
he sense of computational costs scaling linearly in the number of degrees
of freedom. We show that one can achieve optimality of an adaptive Galerki
n scheme for discretizations by spline wavelets \;in the spatial varia
ble when a multiscale representation of the affinely parameterized random
coefficients is used. \;

M. Bachmayr and I. Voulis\, \;*An adaptive stochastic Galerkin method based on multilevel expansions of
random fields: Convergence and optimality*\, \;arXiv:2109:09136

For further informati on about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220318T120000 END:VEVENT BEGIN:VEVENT UID:news1325@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220317T092049 DTSTART;TZID=Europe/Zurich:20220317T173000 SUMMARY:Basel Master’s Info Evening | 17. March 2022 DESCRIPTION:Many students would like to deepen their knowledge after comple ting a bachelor's degree and therefore strive for a master's degree. The M aster’s degree programs at the University of Basel will be presented at the Master’s Info Evening [https://www.unibas.ch/en/Master-Infoevening-2 022.html] on March 17\, 2022. From 17:30 to 20:00\, prospective students c an take part in various online activities to find out more and ask questio ns.\\r\\n\\r\\nPlease find the program of the Department of Mathematics an d Computer Science below:\\r\\n Presentation and open consultation have t he same Zoom link. All the Zoom meetings will be open continuously\, so t hat individual questions can be answered before the presentation. \\r\\n\\ r\\nActuarial Science https://unibas.zoom.us/j/68772491742 [https://unibas .zoom.us/j/68772491742]\\r\\n17:30-18:15 Presentation Master Actuarial S cience and open consultation 18:30-19:15 Meet our Students 19:30-20:00 Presentation Master Actuarial Science and open consultation\\r\\nTestimon ial of MSc student Claudia Theiler: https://www.youtube.com/watch?v=TJ70E1 V-nwc [https://www.youtube.com/watch?v=TJ70E1V-nwc]\\r\\nHERE [t3://file?u id=3128] you can find a short presentation of the Master’s degree in Act uarial Science [t3://page?uid=206](in German).\\r\\n Computer Science htt ps://unibas.zoom.us/j/67965624099 [https://unibas.zoom.us/j/67965624099]\\ r\\n19:30-20:00 Presentation Master Computer Science 17:30-20:00 Open cons ultation\\r\\nHERE [t3://file?uid=3120] you can find a short presentation of the Master’s degree in Computer Science [https://dmi.unibas.ch/en/stu dies/computer-science/masters/] (in German).\\r\\n\\r\\nData Science http s://unibas.zoom.us/j/62557326301 [https://unibas.zoom.us/j/62557326301]\\r \\n18:00-19:00 Presentation Master Data Science and open consultation\\r\\ nHERE [t3://file?uid=3126] you can find a short presentation of the Master ’s degree in Data Science [https://dmi.unibas.ch/de/studium/data-scienc e/](in German).\\r\\n\\r\\nMathematics https://unibas.zoom.us/j/6425778999 3 [https://unibas.zoom.us/j/64257789993]\\r\\n18:30-19:15 Presentation s pecialisation modules FS22/SS23 17:30-20:00 Open consultation\\r\\nHERE [t3://file?uid=3121] you can find a short presentation of the Master’s d egree in Mathematics [https://dmi.unibas.ch/en/studies/mathematics/master/ ] (in German). X-ALT-DESC:Many students would like to deepen their knowledge after comp leting a bachelor's degree and therefore strive for a master's degree. The Master’s degree programs at the University of Basel will be presented a t the Mast er’s Info Evening on March 17\, 2022. From 17:30 to 20:00\, prospect ive students can take part in various online activities to find out more a nd ask questions.

\n\nPlease find the program of the Department of M athematics and Computer Science below:

\n**Presenta tion and open consultation have the same Zoom link.**

**Actuarial Science**

https://unibas.zoom.us/j/68772491742

**17:
30-18:15** \; Presentation Master Actuarial Science and open co
nsultation**18:30-19:15** \; Meet our Students**19:30-20:00** \; Presentation Master Actuarial Scien
ce and open consultation

Testimonial of MSc student Claudia Theile r: https://www.youtu be.com/watch?v=TJ70E1V-nwc

\nHERE you can find a short presentation of the Master’s degree in Actuarial Science (in German).

\n**Computer Scie
nce**

https://
unibas.zoom.us/j/67965624099

**19:30-20:00** Pres
entation Master Computer Science**17:30-20:00** Open c
onsultation

HERE you can find a s hort presentation of the Master’s degree in Computer Science (in German).

\n\n**Data Science **

https://unibas.zoom.us/j/62557326301

HERE you can find a short p resentation of the Master’s degree in Data Science (in German).

\n\n**Mat
hematics**

htt
ps://unibas.zoom.us/j/64257789993

**18:30-19:15**
\; Presentation specialisation modules FS22/SS23**17:30-
20:00** \; Open consultation

HERE you can find a short presentation of the Master’s degree in Mathematics (in German).

DTEND;TZID=Europe/Zurich:20220317T200000 END:VEVENT BEGIN:VEVENT UID:news1300@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220310T151447 DTSTART;TZID=Europe/Zurich:20220317T170000 SUMMARY:Number Theory Web Seminar: Aaron Levin (Michigan State University) DESCRIPTION:The classical Weil height machine associates heights to divisor s on a projective variety. I will give a brief\, but gentle\, introduction to how this machinery extends to objects (closed subschemes) in higher co dimension\, due to Silverman\, and discuss various ways to interpret the h eights. We will then discuss several recent results in which these ideas p lay a prominent and central role.\\r\\nFor further information about the s eminar\, please visit this webpage [https://www.ntwebseminar.org/]. X-ALT-DESC:The classical Weil height machine associates height s to divisors on a projective variety. I will give a brief\, but gentle\, introduction to how this machinery extends to objects (closed subschemes) in higher codimension\, due to Silverman\, and discuss various ways to int erpret the heights. We will then discuss several recent results in which t hese ideas play a prominent and central role.

\nFor further informat ion about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220317T180000 END:VEVENT BEGIN:VEVENT UID:news1315@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220308T100157 DTSTART;TZID=Europe/Zurich:20220314T121500 SUMMARY:Bernoullis Tafelrunde: Marco Inversi (Universität Basel) DESCRIPTION:abstract [t3://file?uid=3125] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220314T130000 END:VEVENT BEGIN:VEVENT UID:news1299@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220301T152844 DTSTART;TZID=Europe/Zurich:20220310T170000 SUMMARY:Number Theory Web Seminar: Dmitry Kleinbock (Brandeis University) DESCRIPTION:Let $\\psi$ be a decreasing function defined on all large posit ive real numbers. We say that a real $m \\times n$ matrix $Y$ is "$\\psi$- Dirichlet" if for every sufficiently large real number $T$ there exist non -trivial integer vectors $(p\,q)$ satisfying $\\|Yq-p\\|^m < \\psi(T)$ and $\\|q\\|^n < T$ (where $\\|\\cdot\\|$ denotes the supremum norm on vector s). This generalizes the property of $Y$ being "Dirichlet improvable" whic h has been studied by several people\, starting with Davenport and Schmidt in 1969. I will present results giving sufficient conditions on $\\psi$ t o ensure that the set of $\\psi$-Dirichlet matrices has zero (resp.\, full ) measure. If time allows I will mention a geometric generalization of the set-up\, where the supremum norm is replaced by an arbitrary norm. Joint work with Anurag Rao\, Andreas Strombergsson\, Nick Wadleigh and Shuchweng Yu.\\r\\nFor further information about the seminar\, please visit this we bpage [https://www.ntwebseminar.org/]. X-ALT-DESC:Let $\\psi$ be a decreasing function defined on all large positive real numbers. We say that a real $m \\times n$ matrix $Y$ is "$\\psi$-Dirichlet" if for every sufficiently large real number $T$ the re exist non-trivial integer vectors $(p\,q)$ satisfying $\\|Yq-p\\|^m < \; \\psi(T)$ and $\\|q\\|^n <\; T$ (where $\\|\\cdot\\|$ denotes the sup remum norm on vectors). This generalizes the property of $Y$ being "Dirich let improvable" which has been studied by several people\, starting with D avenport and Schmidt in 1969. I will present results giving sufficient con ditions on $\\psi$ to ensure that the set of $\\psi$-Dirichlet matrices ha s zero (resp.\, full) measure. If time allows I will mention a geometric g eneralization of the set-up\, where the supremum norm is replaced by an ar bitrary norm. Joint work with Anurag Rao\, Andreas Strombergsson\, Nick Wa dleigh and Shuchweng Yu.

\nFor further information about the seminar \, please visit this webpage.< /p> DTEND;TZID=Europe/Zurich:20220310T180000 END:VEVENT BEGIN:VEVENT UID:news1291@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220301T152634 DTSTART;TZID=Europe/Zurich:20220303T170000 SUMMARY:Number Theory Web Seminar: Ekin Özman (Boğaziçi University) DESCRIPTION:Understanding solutions of Diophantine equations over rationals or more generally over any number field is one of the main problems of nu mber theory. By the help of the modular techniques used in the proof of Fe rmat’s last theorem by Wiles and its generalizations\, it is possible to solve other Diophantine equations too. Understanding quadratic points on the classical modular curve play a central role in this approach. It is al so possible to study the solutions of Fermat type equations over number fi elds asymptotically. In this talk\, I will mention some recent results abo ut these notions for the classical Fermat equation as well as some other D iophantine equations.\\r\\nFor further information about the seminar\, ple ase visit this webpage [https://www.ntwebseminar.org/]. X-ALT-DESC:

Understanding solutions of Diophantine equations ov er rationals or more generally over any number field is one of the main pr oblems of number theory. By the help of the modular techniques used in the proof of Fermat’s last theorem by Wiles and its generalizations\, it is possible to solve other Diophantine equations too. Understanding quadrati c points on the classical modular curve play a central role in this approa ch. It is also possible to study the solutions of Fermat type equations ov er number fields asymptotically. In this talk\, I will mention some recent results about these notions for the classical Fermat equation as well as some other Diophantine equations.

\nFor further information about th e seminar\, please visit this webp age.

DTEND;TZID=Europe/Zurich:20220303T180000 END:VEVENT BEGIN:VEVENT UID:news1311@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220113T175547 DTSTART;TZID=Europe/Zurich:20220302T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Dr. Havva Yoldas (Univer sity of Vienna) DESCRIPTION: I will talk about Harris-type theorems and their applications to several kinetic equations like the linear BGK\, the linear Boltzmann\, the kinetic Fokker-Planck equations and some biological kinetic models li ke the run and tumble equation. Even though the original ideas date back t o the 1940s\, the Harris-type arguments recently raised a lot of mathemati cal interest in the PDE community especially after a simplified proof pro vided by Hairer and Mattingly in 2011. It is a convenient way to obtain qu antifiable convergence rates\, constructive proofs and the existence of a unique stationary state comes as a by-product of the theorems. The latte r is especially useful for kinetic equations arising in biology where the shape of the stationary state cannot be known a priori. X-ALT-DESC:\;I will talk about Harris-type theorems and their appli cations to several kinetic equations like the linear BGK\, the linear Bolt zmann\, the kinetic Fokker-Planck equations and some biological kinetic mo dels like the run and tumble equation. Even though the original ideas date back to the 1940s\, the Harris-type arguments recently raised a lot of ma thematical interest \;in the PDE community especially after a simplifi ed proof provided by Hairer and Mattingly in 2011. It is a convenient way to obtain quantifiable convergence rates\, constructive \;proofs and t he existence of a unique \;stationary state comes as a by-product of t he theorems. The latter is especially useful \;for kinetic equations a rising in biology where the shape of the stationary state cannot be known a priori. \;

DTEND;TZID=Europe/Zurich:20220302T160000 END:VEVENT BEGIN:VEVENT UID:news1314@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220222T101738 DTSTART;TZID=Europe/Zurich:20220228T121500 SUMMARY:Bernoullis Tafelrunde: Irène Meunier (Universität Basel) DESCRIPTION:Abstract [t3://file?uid=3093] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20220228T130000 END:VEVENT BEGIN:VEVENT UID:news1281@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220221T111808 DTSTART;TZID=Europe/Zurich:20220224T181500 SUMMARY:Bernoulli Meets Industry: Dr. Manuela Moor DESCRIPTION:Have you ever wondered what to do after your degree?\\r\\nWe in vite you to the new seminar “Bernoulli meets Industry”\, an evening ev ent where\\r\\nformer mathematicians talk about their current work\, follo wed by an apéro. \\r\\nRegarding Covid: This event will take place in ac cordance with the university regulations.\\r\\nIf you want to participate\ , please register under the following link:\\r\\nRegistration [https://doc s.google.com/forms/d/e/1FAIpQLSd4kyfNmagVc2N_KhQleQoQij7uDBYDLVYyLvWmv5jWP YaqJA/viewform?usp=sf_link]\\r\\nflyer [t3://file?uid=3067]\\r\\n*UPDATE: Due to the current situation\, the talk is open for everyone.* X-ALT-DESC:Have you ever wondered what to do after your degree?

\nWe invite you to the new seminar “Bernoulli meets Industry”\, an eveni ng event where

\nformer mathematicians talk about their current work \, followed by an apéro. \;

\nRegarding Covid: This event will take place in accordance with the university regulations.

\nIf you w ant to participate\, please register under the following link:

\n\n\n*UPDATE: Due to the current sit uation\, the talk is open for everyone.*

DTEND;TZID=Europe/Zurich:20220224T201500 END:VEVENT BEGIN:VEVENT UID:news1290@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220209T111633 DTSTART;TZID=Europe/Zurich:20220224T170000 SUMMARY:Number Theory Web Seminar: Igor Shparlinski (UNSW Sydney) DESCRIPTION:We present some old and more recent results which suggest that Kloosterman and Salie sums exhibit a pseudorandom behaviour similar to the behaviour which is traditionally attributed to the Mobius function. In pa rticular\, we formulate some analogues of the Chowla Conjecture for Kloost erman and Salie sums. We then describe several results about the non-corre lation of Kloosterman and Salie sums between themselves and also with some classical number-theoretic functions such as the Mobius function\, the di visor function and the sums of binary digits. Various arithmetic applicati ons of these results\, including to asymptotic formulas for moments of var ious L-functions\, will be outlined as well.\\r\\nFor further information about the seminar\, please visit this webpage [https://www.ntwebseminar.or g/]. X-ALT-DESC:We present some old and more recent results which suggest tha t Kloosterman and Salie sums exhibit a pseudorandom behaviour similar to t he behaviour which is traditionally attributed to the Mobius function. In particular\, we formulate some analogues of the Chowla Conjecture for Kloo sterman and Salie sums. We then describe several results about the non-cor relation of Kloosterman and Salie sums between themselves and also with so me classical number-theoretic functions such as the Mobius function\, the divisor function and the sums of binary digits. Various arithmetic applica tions of these results\, including to asymptotic formulas for moments of v arious L-functions\, will be outlined as well.

\nFor further informa tion about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220224T180000 END:VEVENT BEGIN:VEVENT UID:news1289@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220209T111403 DTSTART;TZID=Europe/Zurich:20220217T170000 SUMMARY:Number Theory Web Seminar: Harry Schmidt (University of Basel) DESCRIPTION:In this talk I will give an overview of the history of the Andr é-Oort conjecture and its resolution last year after the final steps were made in work of Pila\, Shankar\, Tsimerman\, Esnault and Groechenig as we ll as Binyamini\, Yafaev and myself. I will focus on the key insights and ideas related to model theory and transcendence theory.\\r\\nFor further i nformation about the seminar\, please visit this webpage [https://www.ntwe bseminar.org/]. X-ALT-DESC:In this talk I will give an overview of the history of the An dré-Oort conjecture and its resolution last year after the final steps we re made in work of Pila\, Shankar\, Tsimerman\, Esnault and Groechenig as well as Binyamini\, Yafaev and myself. I will focus on the key insights an d ideas related to model theory and transcendence theory.

\nFor furt her information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220217T180000 END:VEVENT BEGIN:VEVENT UID:news1288@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220131T140633 DTSTART;TZID=Europe/Zurich:20220210T170000 SUMMARY:Number Theory Web Seminar: Zeev Rudnick (Tel Aviv University) DESCRIPTION:The study of uniform distribution of sequences is more than a c entury old\, with pioneering work by Hardy and Littlewood\, Weyl\, van der Corput and others. More recently\, the focus of research has shifted to m uch finer quantities\, such as the distribution of nearest neighbor gaps a nd the pair correlation function. Examples of interesting sequences for wh ich these quantities have been studied include the zeros of the Riemann ze ta function\, energy levels of quantum systems\, and more. In this exposit ory talk\, I will discuss what is known about these examples and discuss t he many outstanding problems that this theory has to offer.\\r\\nFor furth er information about the seminar\, please visit this webpage [https://www. ntwebseminar.org/]. X-ALT-DESC:The study of uniform distribution of sequences is more than a century old\, with pioneering work by Hardy and Littlewood\, Weyl\, van d er Corput and others. More recently\, the focus of research has shifted to much finer quantities\, such as the distribution of nearest neighbor gaps and the pair correlation function. Examples of interesting sequences for which these quantities have been studied include the zeros of the Riemann zeta function\, energy levels of quantum systems\, and more. In this expos itory talk\, I will discuss what is known about these examples and discuss the many outstanding problems that this theory has to offer.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220210T180000 END:VEVENT BEGIN:VEVENT UID:news1287@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220131T135710 DTSTART;TZID=Europe/Zurich:20220203T170000 SUMMARY:Number Theory Web Seminar: Peter Humphries (University of Virginia) DESCRIPTION:A major area of study in analysis involves the distribution of mass of Laplacian eigenfunctions on a Riemannian manifold. A key result to wards this is explicit L^p-norm bounds for Laplacian eigenfunctions in ter ms of their Laplacian eigenvalue\, due to Sogge in 1988. Sogge's bounds ar e sharp on the sphere\, but need not be sharp on other manifolds. I will d iscuss some aspects of this problem for the modular surface\; in this sett ing\, the Laplacian eigenfunctions are automorphic forms\, and certain L^p -norms can be shown to be closely related to certain mixed moments of L-fu nctions. This is joint with with Rizwanur Khan.\\r\\nFor further informati on about the seminar\, please visit this webpage [https://www.ntwebseminar .org/]. X-ALT-DESC:A major area of study in analysis involves the distribution o f mass of Laplacian eigenfunctions on a Riemannian manifold. A key result towards this is explicit L^p-norm bounds for Laplacian eigenfunctions in t erms of their Laplacian eigenvalue\, due to Sogge in 1988. Sogge's bounds are sharp on the sphere\, but need not be sharp on other manifolds. I will discuss some aspects of this problem for the modular surface\; in this se tting\, the Laplacian eigenfunctions are automorphic forms\, and certain L ^p-norms can be shown to be closely related to certain mixed moments of L- functions. This is joint with with Rizwanur Khan.

\nFor further info rmation about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220203T180000 END:VEVENT BEGIN:VEVENT UID:news1286@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220119T084242 DTSTART;TZID=Europe/Zurich:20220127T170000 SUMMARY:Number Theory Web Seminar: Larry Guth (MIT) DESCRIPTION:The Vinogradov mean value conjecture concerns the number of sol utions of a system of diophantine equations. This number of solutions can also be written as a certain moment of a trigonometric polynomial. The con jecture was proven in the 2010s by Bourgain-Demeter-Guth and by Wooley\, a nd recently there was a shorter proof by Guo-Li-Yang-Zorin-Kranich. The de tails of each proof involve some intricate estimates. The goal of the talk is to try to reflect on the proof(s) in a big picture way. A key ingredie nt in all the proofs is to combine estimates at many different scales\, us ually by doing induction on scales. Why does this multi-scale induction he lp? What can multi-scale induction tell us and what are its limitations?\\ r\\nFor further information about the seminar\, please visit this webpage [https://www.ntwebseminar.org/]. X-ALT-DESC:The Vinogradov mean value conjecture concerns the number of s olutions of a system of diophantine equations. This number of solutions ca n also be written as a certain moment of a trigonometric polynomial. The c onjecture was proven in the 2010s by Bourgain-Demeter-Guth and by Wooley\, and recently there was a shorter proof by Guo-Li-Yang-Zorin-Kranich. The details of each proof involve some intricate estimates. The goal of the ta lk is to try to reflect on the proof(s) in a big picture way. A key ingred ient in all the proofs is to combine estimates at many different scales\, usually by doing induction on scales. Why does this multi-scale induction help? What can multi-scale induction tell us and what are its limitations?

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220127T180000 END:VEVENT BEGIN:VEVENT UID:news1312@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220117T140912 DTSTART;TZID=Europe/Zurich:20220124T100000 SUMMARY:PhD Defence Computer Science: Dana Rahbani DESCRIPTION:Abstract: Medical image analysis applications often benefit fro m having a statistical shape model in the background. Statistical shape mo dels are generative models which can generate shapes from the same family and assign a likelihood to the generated shape. In an Analysis-by-synthesi s approach to medical image analysis\, the target shape to be segmented\, registered or completed must first be reconstructed by the statistical sha pe model. Shape models accomplish this by either acting as regression mode ls\, used to obtain the reconstruction\, or as regularizers\, used to limi t the space of possible reconstructions. However\, the accuracy of these m odels is not guaranteed for targets that lie out of the modeled distributi on of the statistical shape model. Targets with pathologies are an example of out-of-distribution data. The target shape to be reconstructed has def ormations caused by pathologies that do not exist on the healthy data used to build the model. Added and missing regions may lead to false correspon dences\, which act as outliers and influence the reconstruction result. Ro bust fitting is necessary to decrease the influence of outliers on the fit ting solution\, but often comes at the cost of decreased accuracy in the i nlier region. Robust techniques often presuppose knowledge of outlier char acteristics to build a robust cost function or knowledge of the correct re gressed function to filter the outliers.\\r\\nThe defence will take place on Zoom. (The meeting ID was sent via email). X-ALT-DESC:Abstract: Medical image analysis applications often benefit f rom having a statistical shape model in the background. Statistical shape models are generative models which can generate shapes from the same famil y and assign a likelihood to the generated shape. In an Analysis-by-synthe sis approach to medical image analysis\, the target shape to be segmented\ , registered or completed must first be reconstructed by the statistical s hape model. Shape models accomplish this by either acting as regression mo dels\, used to obtain the reconstruction\, or as regularizers\, used to li mit the space of possible reconstructions. However\, the accuracy of these models is not guaranteed for targets that lie out of the modeled distribu tion of the statistical shape model. Targets with pathologies are an examp le of out-of-distribution data. The target shape to be reconstructed has d eformations caused by pathologies that do not exist on the healthy data us ed to build the model. Added and missing regions may lead to false corresp ondences\, which act as outliers and influence the reconstruction result. Robust fitting is necessary to decrease the influence of outliers on the f itting solution\, but often comes at the cost of decreased accuracy in the inlier region. Robust techniques often presuppose knowledge of outlier ch aracteristics to build a robust cost function or knowledge of the correct regressed function to filter the outliers.

\nThe defence will take p lace on Zoom. (The meeting ID was sent via email).

END:VEVENT BEGIN:VEVENT UID:news1285@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220117T122020 DTSTART;TZID=Europe/Zurich:20220120T170000 SUMMARY:Number Theory Web Seminar: Jozsef Solymosi (University of British C olumbia) DESCRIPTION:We establish lower bounds on the rank of matrices in which all but the diagonal entries lie in a multiplicative group of small rank. Appl ying these bounds we show that the distance sets of finite pointsets in ℝ^d generate high rank multiplicative groups and that multiplicative gro ups of small rank cannot contain large sumsets. (Joint work with Noga Alon )\\r\\nFor further information about the seminar\, please visit this webpa ge [https://www.ntwebseminar.org/]. X-ALT-DESC:We establish lower bounds on the rank of matrices in which al l but the diagonal entries lie in a multiplicative group of small rank. Ap plying these bounds we show that the distance sets of finite pointsets in ℝ^d generate high rank multiplicative groups and that multiplicative gro ups of small rank cannot contain large sumsets. (Joint work with Noga Alon )

\nFor further information about the seminar\, please visit this webpage.

END:VEVENT BEGIN:VEVENT UID:news1310@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220112T102603 DTSTART;TZID=Europe/Zurich:20220113T170000 SUMMARY:Number Theory Web Seminar: Péter Varjú (University of Cambridge) DESCRIPTION:Consider random polynomials of degree d whose leading and const ant coefficients are 1 and the rest are independent taking the values 0 or 1 with equal probability. A conjecture of Odlyzko and Poonen predicts tha t such a polynomial is irreducible in Z[x] with high probability as d grow s. This conjecture is still open\, but Emmanuel Breuillard and I proved it assuming the Extended Riemann Hypothesis. I will briefly recall the metho d of proof of this result and will discuss later developments that apply t his method to other models of random polynomials.\\r\\nFor further informa tion about the seminar\, please visit this webpage [https://www.ntwebsemin ar.org/]. X-ALT-DESC:Consider random polynomials of degree d whose leading and con stant coefficients are 1 and the rest are independent taking the values 0 or 1 with equal probability. A conjecture of Odlyzko and Poonen predicts t hat such a polynomial is irreducible in Z[x] with high probability as d gr ows. This conjecture is still open\, but Emmanuel Breuillard and I proved it assuming the Extended Riemann Hypothesis. I will briefly recall the met hod of proof of this result and will discuss later developments that apply this method to other models of random polynomials.

\nFor further in formation about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20220113T180000 END:VEVENT BEGIN:VEVENT UID:news1283@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20220112T134708 DTSTART;TZID=Europe/Zurich:20220113T110000 SUMMARY:Bachelor Info Event 2022 DESCRIPTION:Find out more about the diverse range of courses at the Univers ity of Basel. The online information market on Thursday\, January 13th off ers you in-depth insights and lots of information about the courses and su bjects.\\r\\nFurther information and links to the individual events can be found at the web page of the University Basel [https://www.unibas.ch/de/A ktuell/-Veranstaltungen/Basler-Infotag-Bachelor-2021.html] (in German). X-ALT-DESC:Find out more about the diverse range of courses at the Unive rsity of Basel. The online information market on Thursday\, January 13th o ffers you in-depth insights and lots of information about the courses and subjects.

\nFurther information and links to the individual events c an be found at the web page of the University Basel (in German).

DTEND;TZID=Europe/Zurich:20220113T153000 END:VEVENT BEGIN:VEVENT UID:news1279@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211214T144847 DTSTART;TZID=Europe/Zurich:20211221T120000 SUMMARY:Information event bachelor thesis for Computer Science students DESCRIPTION:When: Tuesday\, 21.12.21 12 pm - 2 pm\\r\\nWhere: room HS U1.14 1 in the new Biozentrum and via Zoom (the Zoom meeting ID will be sent via email)\\r\\nTopics:\\r\\n organization of the bachelor thesis topics of bachelor theses supervised by the CS research groups X-ALT-DESC:When: Tuesday\, 21.12.21 12 pm - 2 pm

\nWhere: room HS U1.141 in the new Biozentrum and via Zoom (the Zoom meeting ID will be sen t via email)

\nTopics:

\n- organization of the bachelor t hesis
- topics of bachelor theses supervised by the CS resea rch groups

The PML method is one of the most widely used for the numeric al simulation of wave propagation problems set in unbounded domains. Howev er \;difficulties arise when the exterior domain has some complexity which prevents from using classical approaches. For instance\, it is well- known that PML may be unstable for time-domain eslastodynamic waves in som e anisotropic materials. More recently\, is has also been noticed that sta ndard PML cannot work in presence of some dispersive materials. \;In some cases\, new stable PMLs have been designed.

\nIn this talk\, we address the questions of well-posedness\, stability and convergence of st andard and new models of PMLs in the context of electromagnetic waves for non-dispersive and dispersive materials.

\nFor further information a bout the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211217T120000 END:VEVENT BEGIN:VEVENT UID:news1270@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211206T164028 DTSTART;TZID=Europe/Zurich:20211216T170000 SUMMARY:Number Theory Web Seminar: Sarah Zerbes (University College London\ , UK) DESCRIPTION:Euler systems are one of the most powerful tools for proving ca ses of the Bloch--Kato conjecture\, and other related problems such as the Birch and Swinnerton-Dyer conjecture. I will recall a series of recent wo rks (variously joint with Loeffler\, Pilloni\, Skinner) giving rise to an Euler system in the cohomology of Shimura varieties for GSp(4)\, and an ex plicit reciprocity law relating the Euler system to values of L-functions. I will then recent work with Loeffler\, in which we use this Euler system to prove new cases of the BSD conjecture for modular abelian surfaces ove r Q\, and modular elliptic curves over imaginary quadratic fields.\\r\\nFo r further information about the seminar\, please visit this webpage [https ://www.ntwebseminar.org/]. X-ALT-DESC:Euler systems are one of the most powerful tools for proving
cases of the Bloch--Kato conjecture\, and other related problems such as t
he Birch and Swinnerton-Dyer conjecture.

I will recall a series of r
ecent works (variously joint with Loeffler\, Pilloni\, Skinner) giving ris
e to an Euler system in the cohomology of Shimura varieties for GSp(4)\, a
nd an explicit reciprocity law relating the Euler system to values of L-fu
nctions. I will then recent work with Loeffler\, in which we use this Eule
r system to prove new cases of the BSD conjecture for modular abelian surf
aces over Q\, and modular elliptic curves over imaginary quadratic fields.

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211216T180000 END:VEVENT BEGIN:VEVENT UID:news1254@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211129T110015 DTSTART;TZID=Europe/Zurich:20211213T121500 SUMMARY:Bernoullis Tafelrunde: Damaris Meier (Université de Fribourg) DESCRIPTION:abstract [t3://file?uid=3062] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211213T130000 END:VEVENT BEGIN:VEVENT UID:news1276@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211204T143630 DTSTART;TZID=Europe/Zurich:20211210T110000 SUMMARY:Seminar in Numerical Analysis: Mike Botchev (Keldysh Institute of A pplied Mathematics) DESCRIPTION:An efficient Krylov subspace algorithm for computing actions of the phi matrix function for large matrices is proposed. This matrix funct ion is widely used in exponential time integration\, Markov chains\, and n etwork analysis and many other applications. Our algorithm is based on a reliable residual based stopping criterion and a new efficient restarting procedure. We analyze residual convergence and prove\, for matrices with n umerical range in the stable complex half-plane\, that the restarted metho d is guaranteed to converge for any Krylov subspace dimension. Numerical t ests demonstrate efficiency of our approach for solving large scale evolut ion problems resulting from discretized in space time-dependent PDEs\, in particular\, diffusion and convection-diffusion problems.\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid= 1115]. X-ALT-DESC:An efficient Krylov subspace algorithm for computing actions of the phi matrix function for large matrices is proposed. This matrix fun ction is widely used in exponential time integration\, Markov chains\, and network analysis and many other applications. Our algorithm is based on&n bsp\;a reliable residual based stopping criterion and a new efficient rest arting procedure. We analyze residual convergence and prove\, for matrices with numerical range in the stable complex half-plane\, that the restarte d method is guaranteed to converge for any Krylov subspace dimension. Nume rical tests demonstrate efficiency of our approach for solving large scale evolution problems resulting from discretized in space time-dependent PDE s\, in particular\, diffusion and convection-diffusion problems.

\nF or further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211210T120000 END:VEVENT BEGIN:VEVENT UID:news1269@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211201T103850 DTSTART;TZID=Europe/Zurich:20211209T170000 SUMMARY:Number Theory Web Seminar: Samir Siksek (University of Warwick) DESCRIPTION:The asymptotic Fermat conjecture (AFC) states that for a number field K\, and for sufficiently large primes p\, the only solutions to the Fermat equation X^p+Y^p+Z^p=0 in K are the obvious ones. We sketch recent work that connects the Fermat equation to the far more elementary unit eq uation\, and explain how this surprising connection can be exploited to pr ove AFC for several infinite families of number fields. This talk is based on joint work with Nuno Freitas\, Alain Kraus and Haluk Sengun.\\r\\nFor further information about the seminar\, please visit this webpage [https:/ /www.ntwebseminar.org/]. X-ALT-DESC:The asymptotic Fermat conjecture (AFC) states that for a numb er field K\, and for sufficiently large primes p\, the only solutions to t he Fermat equation X^p+Y^p+Z^p=0 in K are the obvious ones. We sketch rece nt work that connects the Fermat equation to the far more elementary unit equation\, and explain how this surprising connection can be exploited to prove AFC for several infinite families of number fields. This talk is bas ed on joint work with Nuno Freitas\, Alain Kraus and Haluk Sengun.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211208T180000 END:VEVENT BEGIN:VEVENT UID:news1252@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211115T124620 DTSTART;TZID=Europe/Zurich:20211208T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Martina Zizza (SISSA Tri este) DESCRIPTION:In this talk we tackle the question "How many vector fields are mixing?" analyzing the density properties of divergence-free BV vector fields which are weakly mixing/strongly mixing: this means that their Reg ular Lagrangian Flow is a weakly mixing/strongly mixing measure-preserving map when evaluated at time t=1. More precisely we prove the existence of a G_delta-set U in the space L^1_{t\,x}([0\,1]^3) made of divergence-free vector fields such that:\\r\\n 1) weakly mixing vector fields are a residual G_delta-set in U\;\\r\\n 2) (exponentially fast) strongl y mixing vector fields are a dense subset of U.\\r\\nThe proof of these re sults exploits some connections between ergodic theory and fluid dynamics and it is based on the density of BV vector fields whose Regular Lagrangia n Flow is a permutation of subsquares of the unit square [0\,1]^2 when eva luated at time t=1. X-ALT-DESC:In this talk we tackle the question "How many vector fields a re mixing?" analyzing \; \;the density properties of divergence-fr ee BV vector fields which are weakly mixing/strongly mixing: this means th at their Regular Lagrangian Flow is a weakly mixing/strongly mixing measur e-preserving map when evaluated at time t=1. More precisely we prove the e xistence of a \;G_delta-set U in the space L^1_{t\,x}([0\,1]^3) made o f divergence-free vector fields such that:

\n\; \; 1) \; weakly mixing vector fields are a residual G_delta-set in U\;

\n& nbsp\; \; 2) \; (exponentially fast) strongly mixing vector field s are a dense subset of U.

\nThe proof of these results exploits som e connections between ergodic theory and fluid dynamics and it is based on the density of BV vector fields whose Regular Lagrangian Flow is a permut ation of subsquares of the unit square [0\,1]^2 when evaluated at time t=1 . \;

DTEND;TZID=Europe/Zurich:20211208T160000 END:VEVENT BEGIN:VEVENT UID:news1245@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211202T115804 DTSTART;TZID=Europe/Zurich:20211206T121500 SUMMARY:Bernoullis Tafelrunde: Corinne Emmenegger (ETH Zürich) DESCRIPTION:abstract [t3://file?uid=3066] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211206T130000 END:VEVENT BEGIN:VEVENT UID:news1258@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211025T123428 DTSTART;TZID=Europe/Zurich:20211203T110000 SUMMARY:Seminar in Numerical Analysis: Larisa Beilina (Chalmers tekniska h ögskola) DESCRIPTION:We will discuss how to apply an adaptive finite element metho d (AFEM) for numerical solution of an electromagnetic volume integral equ ation. The problem of solution of this equation is formulated as an optim al control problem for minimizing of the Tikhonov's regularization funct ional. A posteriori error estimates for the error in the obtained finite element reconstruction and error in the Tikhonov's functional will be pr esented.\\r\\nBased on these estimates\, different adaptive finite element algorithms are formulated. Numerical examples will show efficiency of t he proposed adaptive algorithms to improve quality of 3D reconstruction of target during the process of microwave thermometry which is used in ca ncer therapies. This is joint work with the group of Biomedical Imaging a t the Department of Electrical Engineering at CTH\, Chalmers.\\r\\nFor fu rther information about the seminar\, please visit this webpage [t3://page ?uid=1115]. X-ALT-DESC:We will \; discuss how to apply an adaptive finite elemen t method (AFEM) for numerical solution of \;an electromagnetic volume integral equation. \;The problem of solution of this equation is formu lated as an optimal \;control problem for minimizing of the Tikhonov's regularization \;functional. \;A posteriori error estimates for t he error in the obtained finite \;element reconstruction and error in the Tikhonov's functional will be presented.

\nBased on these estima tes\, different adaptive finite element algorithms \;are formulated.&n bsp\;Numerical examples will show efficiency of the \;proposed adaptiv e algorithms to improve quality of 3D reconstruction \;of target durin g the process of microwave thermometry which is used in \;cancer thera pies. This is joint work with the group of \;Biomedical Imaging at the Department of Electrical \;Engineering at CTH\, Chalmers.

\nFor further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20211203T120000 END:VEVENT BEGIN:VEVENT UID:news1268@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211125T141706 DTSTART;TZID=Europe/Zurich:20211202T170000 SUMMARY:Number Theory Web Seminar: Kiran Kedlaya (University of California San Diego) DESCRIPTION:We describe several recent results on orders of abelian varieti es over $\\mathbb{F}_2$: every positive integer occurs as the order of an ordinary abelian variety over $\\mathbb{F}_2$ (joint with E. Howe)\; every positive integer occurs infinitely often as the order of a simple abelian variety over $\\mathbb{F}_2$\; the geometric decomposition of the simple abelian varieties over $\\mathbb{F}_2$ can be described explicitly (joint with T. D'Nelly-Warady)\; and the relative class number one problem for fu nction fields is reduced to a finite computation (work in progress). All o f these results rely on the relationship between isogeny classes of abelia n varieties over finite fields and Weil polynomials given by the work of W eil and Honda-Tate. With these results in hand\, most of the work is to co nstruct algebraic integers satisfying suitable archimedean constraints.\\r \\nFor further information about the seminar\, please visit this webpage [ https://www.ntwebseminar.org/]. X-ALT-DESC:

We describe several recent results on orders of abelian varie ties over $\\mathbb{F}_2$: every positive integer occurs as the order of a n ordinary abelian variety over $\\mathbb{F}_2$ (joint with E. Howe)\; eve ry positive integer occurs infinitely often as the order of a simple abeli an variety over $\\mathbb{F}_2$\; the geometric decomposition of the simpl e abelian varieties over $\\mathbb{F}_2$ can be described explicitly (join t with T. D'Nelly-Warady)\; and the relative class number one problem for function fields is reduced to a finite computation (work in progress). All of these results rely on the relationship between isogeny classes of abel ian varieties over finite fields and Weil polynomials given by the work of Weil and Honda-Tate. With these results in hand\, most of the work is to construct algebraic integers satisfying suitable archimedean constraints.< /p>\n

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211202T180000 END:VEVENT BEGIN:VEVENT UID:news1253@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211122T174531 DTSTART;TZID=Europe/Zurich:20211201T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Elia Bruè (Institute fo r Advanced Study\, Princeton) DESCRIPTION:A long-standing open question in fluid mechanics is whether the Yudovich uniqueness result for the 2d Euler system can be extended to the class of L^p-integrable vorticity. Recently\, there have been formidable attempts to disprove this conjecture\, none of which has by now fully solv ed it. I will outline two possible approaches to this problem. One is bas ed on the convex integration technique introduced by De Lellis and Szekely hidi. The second\, proposed recently by Vishik\, exploits the linear insta bility of certain stationary solutions. X-ALT-DESC:A long-standing open question in fluid mechanics is whether t he Yudovich uniqueness result for the 2d Euler system can be extended to t he class of L^p-integrable vorticity. Recently\, there have been formidabl e attempts to disprove this conjecture\, none of which has by now fully so lved it. \;I will outline two possible approaches to this problem. One is based on the convex integration technique introduced by De Lellis and Szekelyhidi. The second\, proposed recently by Vishik\, exploits the linea r instability of certain stationary \;solutions.

DTEND;TZID=Europe/Zurich:20211201T160000 END:VEVENT BEGIN:VEVENT UID:news1244@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211129T110706 DTSTART;TZID=Europe/Zurich:20211129T121500 SUMMARY:Bernoullis Tafelrunde: Yannik Gleichmann (Universität Basel) DESCRIPTION:abstract [t3://file?uid=3063] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211129T130000 END:VEVENT BEGIN:VEVENT UID:news1267@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211125T141908 DTSTART;TZID=Europe/Zurich:20211125T170000 SUMMARY:Number Theory Web Seminar: Alexei Skorobogatov (Imperial College Lo ndon) DESCRIPTION:I will discuss logical links among uniformity conjectures conce rning K3 surfaces and abelian varieties of bounded dimension defined over number fields of bounded degree. The conjectures concern the endomorphism algebra of an abelian variety\, the Néron–Severi lattice of a K3 surfac e\, and the Galois invariant subgroup of the geometric Brauer group. The t alk is based on a joint work with Martin Orr and Yuri Zarhin.\\r\\nFor fur ther information about the seminar\, please visit this webpage [https://ww w.ntwebseminar.org/]. X-ALT-DESC:I will discuss logical links among uniformity conjectures con cerning K3 surfaces and abelian varieties of bounded dimension defined ove r number fields of bounded degree. The conjectures concern the endomorphis m algebra of an abelian variety\, the Néron–Severi lattice of a K3 surf ace\, and the Galois invariant subgroup of the geometric Brauer group. The talk is based on a joint work with Martin Orr and Yuri Zarhin.

\nFo r further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211125T180000 END:VEVENT BEGIN:VEVENT UID:news1259@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211103T092442 DTSTART;TZID=Europe/Zurich:20211124T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Gioacchino Antonelli (Sc uola Normale Superiore di Pisa) DESCRIPTION:In this talk I will discuss the isoperimetric problem on spaces with curvature bounded from below. I will mainly deal with complete non-c ompact Riemannian manifolds\, but most of the techniques described are met ric in nature and the results could be extended to the case of metric meas ure spaces with synthetic bounds from below on the Ricci tensor\, namely R CD spaces. When the space is compact\, the existence of isoperimetric re gions for every volume is established through a simple application of the direct method of Calculus of Variations. In the noncompact case\, part of the mass could be lost at infinity in the minimization process. Such a mas s can be recovered in isoperimetric regions sitting in limits at infinity of the space. Following this heuristics\, and building on top of results b y Ritoré--Rosales and Nardulli\, I will state a generalized existence res ult for the isoperimetric problem on Riemannian manifolds with Ricci curva ture bounded from below and a uniform bound from below on the volumes of u nit balls. The main novelty in such an approach is the use of the syntheti c theory of curvature bounds to describe in a rather natural way where the mass is lost at infinity. Later\, I will use the latter described general ized existence result to prove new existence criteria for the isoperimetri c problem on manifolds with nonnegative Ricci curvature. In particular\, I will show that on a complete manifold with nonnegative sectional curvatur e and Euclidean volume growth at infinity\, isoperimetric regions exist fo r every sufficiently big volume. Time permitting\, I will describe some fo rthcoming works and some open problems. This talk is based on several pa pers and ongoing collaborations with E. Bruè\, M. Fogagnolo\, S. Nardulli \, E. Pasqualetto\, M. Pozzetta\, and D. Semola. X-ALT-DESC:In this talk I will discuss the isoperimetric problem on spac
es with curvature bounded from below. I will mainly deal with complete non
-compact Riemannian manifolds\, but most of the techniques described are m
etric in nature and the results could be extended to the case of metric me
asure spaces with synthetic bounds from below on the Ricci tensor\, namely
RCD spaces. \;

When the space is compact\, the existence of iso
perimetric regions for every volume is established through a simple applic
ation of the direct method of Calculus of Variations. In the noncompact ca
se\, part of the mass could be lost at infinity in the minimization proces
s. Such a mass can be recovered in isoperimetric regions sitting in limits
at infinity of the space. Following this heuristics\, and building on top
of results by Ritoré--Rosales and Nardulli\, I will state a generalized
existence result for the isoperimetric problem on Riemannian manifolds wit
h Ricci curvature bounded from below and a uniform bound from below on the
volumes of unit balls. The main novelty in such an approach is the use of
the synthetic theory of curvature bounds to describe in a rather natural
way where the mass is lost at infinity. Later\, I will use the latter desc
ribed generalized existence result to prove new existence criteria for the
isoperimetric problem on manifolds with nonnegative Ricci curvature. In p
articular\, I will show that on a complete manifold with nonnegative secti
onal curvature and Euclidean volume growth at infinity\, isoperimetric reg
ions exist for every sufficiently big volume. Time permitting\, I will des
cribe some forthcoming works and some open problems. \;

This tal
k is based on several papers and ongoing collaborations with E. Bruè\, M.
Fogagnolo\, S. Nardulli\, E. Pasqualetto\, M. Pozzetta\, and D. Semola.
DTEND;TZID=Europe/Zurich:20211124T160000
END:VEVENT
BEGIN:VEVENT
UID:news1243@dmi.unibas.ch
DTSTAMP;TZID=Europe/Zurich:20211110T162329
DTSTART;TZID=Europe/Zurich:20211122T121500
SUMMARY:Bernoullis Tafelrunde: Tzu-Jan Li (IMJ-PRG)
DESCRIPTION:abstract [t3://file?uid=3023]
X-ALT-DESC:

In the numerical solution of partial differential equations\, it is frequently necessary to ensure that certain variables\, e.g.\, dens ity\, pressure\, or probability density distribution\, remain within stric t bounds. Strict observation of these bounds is crucial\, otherwise unphys ical solutions will be obtained that might result in the failure of the nu merical algorithm. Bounds on certain variables are generally ensured in di scontinuous Galerkin (DG) discretizations using positivity preserving limi ters\, which locally modify the solution to ensure that the constraints ar e satisfied\, while preserving higher order accuracy. In practice this app roach is mostly limited to DG discretizations combined with explicit time integration methods. The combination of (positivity preserving) limiters i n DG discretizations and implicit time integration methods results\, howev er\, in serious problems. Many positivity preserving limiters are not easy to apply in time-implicit DG discretizations and have a non-smooth formul ation\, which hampers the use of standard Newton methods to solve the nonl inear algebraic equations resulting from the time-implicit DG discretizati on. This often results in poor convergence.

\nIn this presentation\, we will discuss a different approach to ensure that a higher order accura te DG solution satisfies the positivity constraints. Instead of using a li miter\, we impose the positivity constraints directly on the algebraic equ ations resulting from a higher order accurate time-implicit DG discretizat ion using techniques from mathematical optimization theory. \;This ap proach ensures that the positivity constraints are satisfied and does not affect the higher order accuracy of the time-implicit DG discretization. T he resulting algebraic equations are then solved using a specially designe d semi-smooth Newton method that is well suited to deal with the resulting nonlinear complementarity problem. We will demonstrate the algorithm on s everal parabolic model problems.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211119T120000 END:VEVENT BEGIN:VEVENT UID:news1265@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211116T092154 DTSTART;TZID=Europe/Zurich:20211118T170000 SUMMARY:Number Theory Web Seminar: Myrto Mavraki (Harvard University) DESCRIPTION:Inspired by an analogy between torsion and preperiodic points\, Zhang has proposed a dynamical generalization of the classical Manin-Mumf ord and Bogomolov conjectures. A special case of these conjectures\, for ` split' maps\, has recently been established by Nguyen\, Ghioca and Ye. In particular\, they show that two rational maps have at most finitely many c ommon preperiodic points\, unless they are `related'. Recent breakthroughs by Dimitrov\, Gao\, Habegger and Kühne have established that the classic al Bogomolov conjecture holds uniformly across curves of given genus. In t his talk we discuss uniform versions of the dynamical Bogomolov conjecture across 1-parameter families of certain split maps. To this end\, we estab lish an instance of a 'relative dynamical Bogomolov'. This is work in prog ress joint with Harry Schmidt (University of Basel).\\r\\nFor further info rmation about the seminar\, please visit this webpage [https://www.ntwebse minar.org/]. X-ALT-DESC:Inspired by an analogy between torsion and preperiodic points
\, Zhang has proposed a dynamical generalization of the classical Manin-Mu
mford and Bogomolov conjectures. A special case of these conjectures\, for
`split' maps\, has recently been established by Nguyen\, Ghioca and Ye. I
n particular\, they show that two rational maps have at most finitely many
common preperiodic points\, unless they are `related'. Recent breakthroug
hs by Dimitrov\, Gao\, Habegger and Kühne have established that the class
ical Bogomolov conjecture holds uniformly across curves of given genus.

In this talk we discuss uniform versions of the dynamical Bogomolov co
njecture across 1-parameter families of certain split maps. To this end\,
we establish an instance of a 'relative dynamical Bogomolov'. This is work
in progress joint with Harry Schmidt (University of Basel).

For f urther information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211118T180000 END:VEVENT BEGIN:VEVENT UID:news1242@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211115T144339 DTSTART;TZID=Europe/Zurich:20211115T121500 SUMMARY:Bernoullis Tafelrunde: Gabriele Visentin (Universität Zürich) DESCRIPTION:abstract [t3://file?uid=3022] slides [t3://file?uid=3026] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211115T130000 END:VEVENT BEGIN:VEVENT UID:news1257@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211025T121842 DTSTART;TZID=Europe/Zurich:20211112T110000 SUMMARY:Seminar in Numerical Analysis: Rolf Krause (Università della Svizz era italiana) DESCRIPTION:Non-convex minimization problems show up in manifold applicatio ns: non-linear elasticity\, phase field models\, fracture propagation\, or the training of neural networks. Traditional multilevel decompositions a re the basic ingredient of the most efficient class of solution methods for linear systems\, i.e. of multigrid methods\, which allow to solve cert ain classes of linear systems with optimal complexity. The transfer of the se concepts to non-linear problems\, however\, is not straightforward\, ne ither in terms of the design of the multilevel decomposition nor in terms of convergence properties. In this talk\, we will discuss multilevel dec ompositions for convex\, non-convex and possibly non-smooth minimization p roblems. We will discuss in detail how multilevel optimization methods c an be constructed and analyzed and we will illustrate the sometimes sign ificant gain in performance\, which can be achieved by multilevel minimiza tion techniques. Examples from mechanics\, geophysics\, and machine learni ng will illustrate our discussion.\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Non-convex minimization problems show up in manifold applicat
ions: non-linear elasticity\, phase field models\, fracture propagation\,
or the training of neural networks.

Traditional multilevel de
compositions are the basic ingredient \;of the most efficient class o
f solution methods for linear systems\, i.e. of multigrid methods\, which
allow to solve certain classes of linear systems with optimal complexity.
The transfer of these concepts to non-linear problems\, however\, is not s
traightforward\, neither in terms of the design of the multilevel decompos
ition nor in terms of convergence properties. In this talk\, we will discu
ss \;multilevel decompositions for convex\, non-convex and possibly n
on-smooth minimization problems. We will discuss in detail how \;mult
ilevel optimization methods can be constructed and analyzed and we will il
lustrate \;the sometimes significant gain in performance\, which can
be achieved by multilevel minimization techniques. Examples from mechanics
\, geophysics\, and machine learning will illustrate our discussion.

For further information about the seminar\, please visit this webpage< /a>.

DTEND;TZID=Europe/Zurich:20211112T120000 END:VEVENT BEGIN:VEVENT UID:news1261@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;TZID=Europe/Zurich:20211111T170000 SUMMARY:Number Theory Web Seminar: Avi Wigderson (Institute for Advanced St udy) DESCRIPTION:Is the universe inherently deterministic or probabilistic? Perh aps more importantly - can we tell the difference between the two?\\r\\nHu manity has pondered the meaning and utility of randomness for millennia.\\ r\\nThere is a remarkable variety of ways in which we utilize perfect coin tosses to our advantage: in statistics\, cryptography\, game theory\, alg orithms\, gambling... Indeed\, randomness seems indispensable! Which of th ese applications survive if the universe had no (accessible) randomness in it at all? Which of them survive if only poor quality randomness is avail able\, e.g. that arises from somewhat "unpredictable" phenomena like the w eather or the stock market?\\r\\nA computational theory of randomness\, de veloped in the past several decades\, reveals (perhaps counter-intuitively ) that very little is lost in such deterministic or weakly random worlds. In the talk I'll explain the main ideas and results of this theory\, notio ns of pseudo-randomness\, and connections to computational intractability. \\r\\nIt is interesting that Number Theory played an important role throug hout this development. It supplied problems whose algorithmic solution mak e randomness seem powerful\, problems for which randomness can be eliminat ed from such solutions\, and problems where the power of randomness remain s a major challenge for computational complexity theorists and mathematici ans. I will use these problems (and others) to demonstrate aspects of this theory.\\r\\nFor further information about the seminar\, please visit thi s webpage [https://www.ntwebseminar.org/]. X-ALT-DESC:Is the universe inherently deterministic or probabilistic? Pe rhaps more importantly - can we tell the difference between the two?

\nHumanity has pondered the meaning and utility of randomness for millenn ia.

\nThere is a remarkable variety of ways in which we utilize perf ect coin tosses to our advantage: in statistics\, cryptography\, game theo ry\, algorithms\, gambling... Indeed\, randomness seems indispensable! Whi ch of these applications survive if the universe had no (accessible) rando mness in it at all? Which of them survive if only poor quality randomness is available\, e.g. that arises from somewhat "unpredictable" phenomena li ke the weather or the stock market?

\nA computational theory of rand omness\, developed in the past several decades\, reveals (perhaps counter- intuitively) that very little is lost in such deterministic or weakly rand om worlds. In the talk I'll explain the main ideas and results of this the ory\, notions of pseudo-randomness\, and connections to computational intr actability.

\nIt is interesting that Number Theory played an importa nt role throughout this development. It supplied problems whose algorithmi c solution make randomness seem powerful\, problems for which randomness c an be eliminated from such solutions\, and problems where the power of ran domness remains a major challenge for computational complexity theorists a nd mathematicians. I will use these problems (and others) to demonstrate a spects of this theory.

\nFor further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211111T180000 END:VEVENT BEGIN:VEVENT UID:news1255@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211021T155955 DTSTART;TZID=Europe/Zurich:20211103T141500 SUMMARY:Seminar Analysis and Mathematical Physics: In-Jee Jeong (Seoul Nati onal University) DESCRIPTION:The evolution of incompressible inviscid fluids is governed by the Euler equations. We consider the dynamics of vortex rings\, which are axisymmetric solutions to the three dimensional Euler equations with conce ntrated axial vorticity. We prove the following infinite norm growth resul ts: (i) filamentation (formation of a long tail) behavior from a single vo rtex ring\, and (ii) vortex stretching from the "collision" of two vortex rings with opposite signs. Joint work with Kyudong Choi (UNIST). X-ALT-DESC:The evolution of incompressible inviscid fluids is governed b y the Euler equations. We consider the dynamics of vortex rings\, which ar e axisymmetric solutions to the three dimensional Euler equations with con centrated axial vorticity. We prove the following infinite norm growth res ults: (i) filamentation (formation of a long tail) behavior from a single vortex ring\, and (ii) vortex stretching from the "collision" of two vorte x rings with opposite signs. \;Joint work with Kyudong Choi (UNIST). DTEND;TZID=Europe/Zurich:20211103T160000 END:VEVENT BEGIN:VEVENT UID:news1239@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210923T100158 DTSTART;TZID=Europe/Zurich:20211101T121500 SUMMARY:Bernoullis Tafelrunde: Anna Bot (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2997] X-ALT-DESC:

DTEND;TZID=Europe/Zurich:20211101T130000 END:VEVENT BEGIN:VEVENT UID:news1256@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211025T121402 DTSTART;TZID=Europe/Zurich:20211029T110000 SUMMARY:Seminar in Numerical Analysis: Jochen Garke (Rheinische Friedrich-W ilhelms-Universität Bonn) DESCRIPTION:We present a conceptual framework that helps to bridge the know ledge gap between the two individual communities from machine learning an d numerical simulation to identify potential combined approaches and to promote the development of hybrid systems. We give examples of different types of combinations using exemplary approaches of simulation-assisted m achine learning and machine-learning assisted simulation. We also discuss an advanced pairing where we see particular further potential for hybrid systems.\\r\\nFor further information about the seminar\, please visit th is webpage [t3://page?uid=1115]. X-ALT-DESC:We present a conceptual framework that helps to bridge the kn
owledge gap \;between the two individual communities from machine lear
ning and \;numerical simulation to identify potential combined approac
hes and to \;promote the development of hybrid systems.

W
e give examples of different types of combinations using exemplary \;a
pproaches of simulation-assisted machine learning and machine-learning&nbs
p\;assisted simulation. We also discuss an advanced pairing where we see&n
bsp\;particular further potential for hybrid systems.

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20211029T120000 END:VEVENT BEGIN:VEVENT UID:news1241@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211021T152000 DTSTART;TZID=Europe/Zurich:20211025T121500 SUMMARY:Bernoullis Tafelrunde: Simone Steinbrüchel (Universität Leipzig) DESCRIPTION:abstract [t3://file?uid=3014] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211025T130000 END:VEVENT BEGIN:VEVENT UID:news1240@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211115T144552 DTSTART;TZID=Europe/Zurich:20211018T121500 SUMMARY:Bernoullis Tafelrunde: Eduardas Lazebnyj (abaQon) DESCRIPTION:abstract [t3://file?uid=3013] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211018T130000 END:VEVENT BEGIN:VEVENT UID:news1230@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210929T113815 DTSTART;TZID=Europe/Zurich:20211007T183000 SUMMARY:A picture can tell more than 1000 lies - a talk on visual fake news DESCRIPTION:Deep Fakes\, Photoshop\, Fake News - Silvan Heller talks about the latest from the world of visual manipulation. The talk takes place on the occasion of the “Schwizerhüsli” young talent award of the Ferdina nd Neeracher-Pfrunder Foundation 2019.\\r\\n After the talk\, there will b e an apéro at Socinstrasse 8\, 4051 Basel.\\r\\n A valid Covid certificat e is required to participate in the event. Please note that the entry is l ocated at Hebelstrasse 12 (certificate checkpoint). X-ALT-DESC:Deep Fakes\, Photoshop\, Fake News - Silvan Heller talks abou t the latest from the world of visual manipulation. The talk takes place o n the occasion of the “Schwizerhüsli” young talent award of the Ferdi nand Neeracher-Pfrunder Foundation 2019.

\n

After the talk\, t
here will be an apéro at Socinstrasse 8\, 4051 Basel.

The concept of measure-valued solution was introduced to the theory of hyperbolic conservation laws by DiPerna in the 1980s. For nonlin ear systems of hyperbolic type\, such as the Euler equations of ideal flui ds\, measure-valued solutions are often the only available notion of solut ion\, as the existence of 'honest' solutions is still unknown. Although th is relaxation of the solution concept seems like a vast generalization\, w here a lot of infomation is lost\, it turned out in work of Székelyhidi-W . (2012) that every measure-valued solution can be approximated by weak on es in the incompressible situation. For compressible flows\, however\, the situation is much different. I will discuss recent progress in this direc tion in joint work with Dennis Gallenmüller.

DTEND;TZID=Europe/Zurich:20211006T160000 END:VEVENT BEGIN:VEVENT UID:news1232@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211007T104530 DTSTART;TZID=Europe/Zurich:20211004T121500 SUMMARY:Bernoullis Tafelrunde: Tim De Ryck (ETH Zürich) DESCRIPTION:abstract [t3://file?uid=2986] slides [t3://file?uid=3008] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20211004T130000 END:VEVENT BEGIN:VEVENT UID:news1237@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210921T162152 DTSTART;TZID=Europe/Zurich:20210929T161500 SUMMARY:PhD Defense Computer Science: Philipp Seidenschwarz DESCRIPTION:The defense is open to members of the university.\\r\\nFor the access link\, please contact Prof. Heiko Schuldt (heiko.schuldt@unibas.ch) . X-ALT-DESC:The defense is open to members of the university.

\nFor the access link\, please contact Prof. Heiko Schuldt (heiko.schuldt@uniba s.ch).

END:VEVENT BEGIN:VEVENT UID:news1220@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211115T144612 DTSTART;TZID=Europe/Zurich:20210927T121500 SUMMARY:Bernoullis Tafelrunde: Remo von Rickenbach (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2989] slides [t3://file?uid=3009] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210927T130000 END:VEVENT BEGIN:VEVENT UID:news1228@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210908T121859 DTSTART;TZID=Europe/Zurich:20210923T161500 SUMMARY:PhD Defense Mathematics: Simon Michel DESCRIPTION:The talk is open to members of the university.\\r\\nFor the acc ess link\, please contact Simon Michel (simon.michel@unibas.ch). X-ALT-DESC:The talk is open to members of the university.

\nFor th e access link\, please contact Simon Michel (simon.michel@unibas.ch).

END:VEVENT BEGIN:VEVENT UID:news1233@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210920T103503 DTSTART;TZID=Europe/Zurich:20210920T161500 SUMMARY:Information event for freshmen DESCRIPTION:Practical Information from Prof. Malte Helmert (computer scienc e) and Prof. Enno Lenzmann (mathematics) Getting to know the other first semester students as well as the "higher semesters" The “Fachgruppe” of Mathematics and Computer Science (FMI) introduces itself Time for your questions \\r\\nFor questions please contact Heidi Karypidis [mailto:heid i.karypidis@unibas.ch] (mathematics) or Heike Freiberger [mailto:heike.fre iberger@unibas.ch] (computer science). X-ALT-DESC:- Practical Information from Prof. Malte Hel mert (computer science) and Prof. Enno Lenzmann (mathematics)
- Getting to know the other first semester students as well as the "higher semesters"
- The “Fachgruppe” of Mathematics and Computer Science (FMI) introduces itse lf
- Time for your questions

For questions please contact Heidi Karypidis (mathematics) or Heike Freiberger (computer science).

\n\n END:VEVENT BEGIN:VEVENT UID:news1226@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210908T171529 DTSTART;TZID=Europe/Zurich:20210915T170000 SUMMARY:Award ceremony of the Prix Schläfli «Mathematics» 2021 DESCRIPTION:Dr. Gabriel Dill has been awarded by the Prix Schläfli "Mathem atics" 2021 for his evidence in Diophantine geometry.\\r\\nParticipants mu st be registered. Participants also need a valid Covid certificate.\\r\\nI f you would like to attend the award ceremony\, please register here:\\r\\ nRegistration award ceremony [https://www.eventbrite.com/e/169427392893]\\ r\\nIf you would like to attend the Apéro\, please also register here:\\r \\nRegistration Apéro [https://www.eventbrite.com/e/169428865297] X-ALT-DESC:Dr. Gabriel Dill has been awarded by the Prix Schläfli "Math ematics" 2021 for his evidence in Diophantine geometry.

\nParticipan ts must be registered. Participants also need a valid Covid certificate.\n

If you would like to attend the award ceremony\, please register he re:

\n\nIf you would like to attend
the Apéro\, please __ also__ register here:

< strong>Registration Ap éro

\n\n DTEND;TZID=Europe/Zurich:20210915T200000 END:VEVENT BEGIN:VEVENT UID:news1221@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210830T113450 DTSTART;TZID=Europe/Zurich:20210910T153000 SUMMARY:Closing Event Fascinating Informatics DESCRIPTION:The closing event of the Fascinating Informatics study week is open to the public. If you would like to attend please register here [http s://forms.office.com/pages/responsepage.aspx?id=dl3g6uk3Z0SMa7m81ZYpEnfhyK KWwKZGjlD2nEd0p2pUMVoySlNJNFRGODkwUExTSkxBM0FGVlVVOCQlQCN0PWcu] by Septemb er 6\, 2021. Face masks are mandatory. X-ALT-DESC:The closing event of the Fascinating Informatics study week i
s open to the public. If you would like to attend please register here<
/a> by **September 6\, 2021**. Face masks are mandatory.

Inspired by of the analogy that exists between quadratic twis ts and real quadratic fields\, we show an estimate for the number of quadr atic twists of a given elliptic curve having a nontorsion rational point w hose canonical height is almost minimal. This establishes an analogue of a result of Hooley about the fundamental solution of the Pell equation.

\nThe talk is open to members of the university.

\nFor the access link\, please contact Gaston Joachim Petit (joachim.petit@unibas.ch).

END:VEVENT BEGIN:VEVENT UID:news1157@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210627T202913 DTSTART;TZID=Europe/Zurich:20210604T110000 SUMMARY:Seminar in Numerical Analysis: Ivan Dokmanić (Universität Basel) DESCRIPTION:This talk will be an overview of my group's research between de ep learning and inverse problems. I will first describe the current (?) st ate of the field and then present a medley of our results\, including 1) a neural network architecture for wave-based inverse problems derived from Fourier integral operators\; 2) an approach to nonlinear traveltime tomogr aphy based on neural priors\; and 3) provably injective neural networks th at are universal approximators of probability measures supported on low-di mensional manifolds. My secret hope is to spark discussions that could evo lve to collaborations.\\r\\nFor further information about the seminar\, pl ease visit this webpage [t3://page?uid=1115]. X-ALT-DESC:This talk will be an overview of my group's research between deep learning and inverse problems. I will first describe the current (?) state of the field and then present a medley of our results\, including 1) a neural network architecture for wave-based inverse problems derived fro m Fourier integral operators\; 2) an approach to nonlinear traveltime tomo graphy based on neural priors\; and 3) provably injective neural networks that are universal approximators of probability measures supported on low- dimensional manifolds. My secret hope is to spark discussions that could e volve to collaborations.

\nFor further information about the seminar \, please visit this webpage.

DTEND;TZID=Europe/Zurich:20210604T120000 END:VEVENT BEGIN:VEVENT UID:news1190@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210601T082910 DTSTART;TZID=Europe/Zurich:20210602T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Corentin Le Bihan (ENS L yon) DESCRIPTION:A simple model of gas is the hard spheres model. It is a billia rd of little particles which can interact very strongly at very small dist ance (think for example of real billiards with a lot of balls). Because un derstanding such system is an outstanding problem\, people tried to find a limiting process. A first equation governing the density of one particle was given by Boltzmann :∂tf+v⋅∇xf=Q(f\,f)\\r\\nIn its formal derivat ion Boltzmann supposed that two different particles are almost independent \, so the probability of having two particles at the same place is the the product of probability. The validity of such equation is a priori not cle ar since it adds some irreversibly that does not exist in the hard sphere model.\\r\\nLanford solved the problem in its ‘75 paper: Boltzmann’s e quation is true\, up to a time independent of the number of particles (how ever each particle will have in mean less than one collision).\\r\\nNow co mes the question of the boundary. We expect to find some “Lanfords” th eorem even if we add some boundary condition. A first example are the spec ular reflections\, for a deterministic law. An other example\, which would be very important in physics\, is the evolution of a gas between two hot plaques. Then the reflection condition is stochastic. I am interested in a third type of reflection\, also stochastic\, which is a modeling of a rou gh boundary.\\r\\nDuring my talk I will present some ideas of the proof of Boltzmann in the torus R^3/Z^3 and the adaptation in the case of a domain with boundaries. X-ALT-DESC:A simple model of gas is the hard spheres model. It is a bill
iard of little particles which can interact very strongly at very small di
stance (think for example of real billiards with a lot of balls). Because
understanding such system is an outstanding problem\, people tried to find
a limiting process. A first equation governing the density of one particl
e was given by Boltzmann :∂*t**f*+*v*⋅
∇*x**f*=*Q*(*f
*\,*f*)

In its formal derivation Boltzman
n supposed that two different particles are almost independent\, so the pr
obability of having two particles at the same place is the the product of
probability. The validity of such equation is *a priori *not clear
since it adds some irreversibly that does not exist in the hard sphere mod
el.

Lanford solved the problem in its ‘75 paper: Boltzmann’s e quation is true\, up to a time independent of the number of particles (how ever each particle will have in mean less than one collision).

\nNow comes the question of the boundary. We expect to find some “Lanfords” theorem even if we add some boundary condition. A first example are the s pecular reflections\, for a deterministic law. An other example\, which wo uld be very important in physics\, is the evolution of a gas between two h ot plaques. Then the reflection condition is stochastic. I am interested i n a third type of reflection\, also stochastic\, which is a modeling of a rough boundary.

\nDuring my talk I will present some ideas of the pr oof of Boltzmann in the torus R^3/Z^3 and the adaptation in the case of a domain with boundaries.

DTEND;TZID=Europe/Zurich:20210602T160000 END:VEVENT BEGIN:VEVENT UID:news1201@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210526T105514 DTSTART;TZID=Europe/Zurich:20210528T120000 SUMMARY:Public Screening of «Picture a Scientist» DESCRIPTION:The «We are Computer Science» association is happy to invite you to a screening of the fascinating documentary «Picture a Scientist». \\r\\n«PICTURE A SCIENTIST chronicles the groundswell of researchers who are writing a new chapter for women scientists. Biologist Nancy Hopkins\, chemist Raychelle Burks\, and geologist Jane Willenbring lead viewers on a journey deep into their own experiences in the sciences\, ranging from br utal harassment to years of subtle slights. Along the way\, from cramped l aboratories to spectacular field stations\, we encounter scientific lumina ries – including social scientists\, neuroscientists\, and psychologists – who provide new perspectives on how to make science itself more diver se\, equitable\, and open to all».\\r\\nYou can watch the trailer of the documentary here [https://www.pictureascientist.com/media].\\r\\nThe scree ning will be available from May 28\, 12:00pm until May 30\, 12:00pm via a personalized Vimeo link. You can watch the movie anytime during this perio d. To get access to the link\, please fill in this form [https://docs.goog le.com/forms/d/e/1FAIpQLSfnZKunF2mlDtd3kO1bYutvsg3srJ744Ehul9jcjAkvpr1rVw/ viewform].\\r\\nSince there is only a limited number of tickets available\ , they will be handed out to members of the «We are Computer Science» as sociation with first priority followed by students and members of Departme nt of Mathematics and Computer Science at the University of Basel and then to all other applicants. X-ALT-DESC:The «We are Computer Science» association is happy to invit e you to a screening of the fascinating documentary «Picture a Scientist ».

\n«**PICTURE A SCIENTIST** chronicles the groundsw
ell of researchers who are writing a new chapter for women scientists. Bio
logist Nancy Hopkins\, chemist Raychelle Burks\, and geologist Jane Willen
bring lead viewers on a journey deep into their own experiences in the sci
ences\, ranging from brutal harassment to years of subtle slights. Along t
he way\, from cramped laboratories to spectacular field stations\, we enco
unter scientific luminaries – including social scientists\, neuroscienti
sts\, and psychologists – who provide new perspectives on how to make sc
ience itself more diverse\, equitable\, and open to all».

You can watch the trailer of the documentary here.

\nThe screening will be available from **
this form**.

**Since there is only a limited numb
er of tickets available\, they will be handed out to members of the «We a
re Computer Science»association with first priority fol
lowed by students and members of Department of Mathematics and Computer Sc
ience at the University of Basel and then to all other applicants.**

The half-wave maps (HWM) equation is a recently-introduced in tegrable PDE with two distinct relations to the (trigonometric) spin \ ;Calogero-Moser-Sutherland (CMS) many-body \;system. Firstly\, the HWM equation arises as a certain continuum limit of the CMS system and second ly\, the soliton solutions of the HWM equation are governed by a complexif ied version of the \;CMS system. We present generalizations of the HWM equation that are similarly related to the \;hyperbolic and elliptic spin \;CMS systems. \;This talk is based on joint work with Rob Kl abbers and Edwin Langmann.

DTEND;TZID=Europe/Zurich:20210526T151500 END:VEVENT BEGIN:VEVENT UID:news1176@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210517T094220 DTSTART;TZID=Europe/Zurich:20210519T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Théotime Girardot (LPMM C) DESCRIPTION:In two-dimensional space there are possibilities for quantum st atistics continuously interpolating between the bosonic and the fermionic one. \\r\\nQuasi-particles obeying such statistics can be described as ord inary bosons and fermions with magnetic interactions. \\r\\nWe study a lim it situation where the statistics/magnetic interaction is seen as a “per turbation from the fermionic end”. \\r\\nWe vindicate a mean-field appro ximation\, proving that the ground state of a gas of anyons is described t o leading order by a semi-classical\, Vlasov-like\, energy functional.\\r\ \nThe ground state of the latter displays anyonic behavior in its momentum distribution. After introducing and stating this result I will give eleme nts of proof based on coherent states\,\\r\\nHusimi functions\, the Diacon is-Freedman theorem and a quantitative version of a semi-classical Pauli p inciple. X-ALT-DESC:In two-dimensional space there are possibilities for quantum statistics continuously interpolating between the bosonic and the fermioni c one.

\nQuasi-particles obeying such statistics can be described a s ordinary bosons and fermions with magnetic interactions.

\nWe stu dy a limit situation where the statistics/magnetic interaction is seen as a “perturbation from the fermionic end”.

\nWe vindicate a mean- field approximation\, proving that the ground state of a gas of anyons is described to leading order by a semi-classical\, Vlasov-like\, energy func tional.

\nThe ground state of the latter displays anyonic behavior i n its momentum distribution. After introducing and stating this result I w ill give elements of proof based on coherent states\,

\nHusimi funct ions\, the Diaconis-Freedman theorem and a quantitative version of a semi- classical Pauli pinciple.

DTEND;TZID=Europe/Zurich:20210519T160000 END:VEVENT BEGIN:VEVENT UID:news1199@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210517T090409 DTSTART;TZID=Europe/Zurich:20210518T173000 SUMMARY:Gender Stereotypes and Gender Balance in Informatics: Time to Act? DESCRIPTION:The We are Computer Science [https://we-are-cs.unibas.ch/en/] a ssociation cordially invites you to a virtual lecture by Dr. Monica Landon i\, head of a research group at the Faculty of Computer Science at Univers ità della Svizzera italiana.\\r\\nHer research interests lie mainly in th e fields of Interactive Information Retrieval and Electronic Publishing\, particularly in the area of design and evaluation of Child-Computer Intera ctions when reading\, writing and searching. She is very keen to explore h ow to use Design for Gender Balance\, Accessibility and Inclusiveness.\\r\ \nThe event is open to the public and free of charge using the registratio n link [https://www.eventbrite.com/e/gender-stereotypes-and-gender-balance -in-informatics-time-to-act-tickets-154675934885] X-ALT-DESC:The We are Computer Science association cordially invites you to a virtual lecture by Dr. Monica Landoni\, head of a research group at the Faculty of Computer Scie nce at Università della Svizzera italiana.

\nHer research interests lie mainly in the fields of Interactive Information Retrieval and Electro nic Publishing\, particularly in the area of design and evaluation of Chil d-Computer Interactions when reading\, writing and searching. She is very keen to explore how to use Design for Gender Balance\, Accessibility and I nclusiveness.

\nThe event is open to the public and free of charge u sing the registration l ink

\n\n END:VEVENT BEGIN:VEVENT UID:news1186@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210515T195106 DTSTART;TZID=Europe/Zurich:20210517T121500 SUMMARY:Bernoullis Tafelrunde: Felix Leopoldo Rios (University of Basel) DESCRIPTION:abstract [t3://file?uid=2862] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210517T130000 END:VEVENT BEGIN:VEVENT UID:news1183@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210507T154831 DTSTART;TZID=Europe/Zurich:20210510T121500 SUMMARY:Bernoullis Tafelrunde: Sebastian Schlegel Mejia (University of Edin burgh) DESCRIPTION:abstract [t3://file?uid=2852] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210510T130000 END:VEVENT BEGIN:VEVENT UID:news1158@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210627T202830 DTSTART;TZID=Europe/Zurich:20210507T110000 SUMMARY:Seminar in Numerical Analysis: Erik Burman (University College Lond on) DESCRIPTION:In many applications both in medical science and in the geoscie nces the accurate approximation of solutions to wave equations is an impor tant component for optimisation or inverse identification. Examples inclu de thermoacoustic imaging or high frequency ultrasound treatments in medic ine (HIFU) or fault slip analysis in seismology. These problems have in c ommon the need for computational solution of an inverse problem where the forward problem is set in a heterogeneous domain. Indeed typically the sou nd speed in the bulk domain jumps over material interfaces. Sometimes ther e is even a need for coupling of the acoustic and elastodynamic equations in the presence of liquid inclusions. In this talk we will give a snapshot of our ongoing work in these topics\, motivated by two such applications: HIFU and the propagation of seismic waves. After a brief introduction of the applications we will first discuss the analysis of some approximation methods for inverse initial value problems subject to the wave equation. W e will then consider a hybrid high order method for the approximation of w ave propagation in heterogeneous media\, using cut element techniques to a void meshing of interfaces. Finally we will discuss some open problems tha t remain in order to understand the approximation of the inverse initial v alue problem in heterogeneous media using high order methods.\\r\\nFor fur ther information about the seminar\, please visit this webpage [t3://page? uid=1115]. X-ALT-DESC:In many applications both in medical science and in the geosc iences the accurate approximation of solutions to wave equations is an imp ortant \;component for optimisation or inverse identification. Example s include thermoacoustic imaging or high frequency ultrasound treatments i n medicine (HIFU) \;or fault slip analysis in seismology. These proble ms have in common the need for computational solution of an inverse proble m where the forward problem is set in a heterogeneous domain. Indeed typic ally the sound speed in the bulk domain jumps over material interfaces. So metimes there is even a need for coupling of the acoustic and elastodynami c equations in the presence of liquid inclusions. In this talk we will giv e a snapshot of our ongoing work in these topics\, motivated by two such a pplications: HIFU and the propagation of seismic waves. After a brief intr oduction of the applications we will first discuss the analysis of some ap proximation methods for inverse initial value problems subject to the wave equation. We will then consider a hybrid high order method for the approx imation of wave propagation in heterogeneous media\, using cut element tec hniques to avoid meshing of interfaces. Finally we will discuss some open problems that remain in order to understand the approximation of the inver se initial value problem in heterogeneous media using high order methods.< /p>\n

For further information about the seminar\, please visit this web page.

DTEND;TZID=Europe/Zurich:20210507T120000 END:VEVENT BEGIN:VEVENT UID:news1184@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210627T202737 DTSTART;TZID=Europe/Zurich:20210430T110000 SUMMARY:Seminar in Numerical Analysis: Pieter Barendrecht (KAUST) DESCRIPTION:In this talk\, we're going to take a closer look at the basics of both univariate and bivariate splines\, including Bézier- and B-spline curves\, box splines and subdivision surfaces. Next\, we'll shift our foc us to applications of smooth spline surfaces of arbitrary manifold topolog y within the realm of computer graphics. Finally\, a couple of aspects and applications of splines in the context of numerical methods will be discu ssed. Expect more illustrations than equations\, and in addition a couple of (interactive) live software demos!\\r\\nFor further information about t he seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:In this talk\, we're going to take a closer look at the basic s of both univariate and bivariate splines\, including Bézier- and B-spli ne curves\, box splines and subdivision surfaces. Next\, we'll shift our f ocus to applications of smooth spline surfaces of arbitrary manifold topol ogy within the realm of computer graphics. Finally\, a couple of aspects a nd applications of splines in the context of numerical methods will be dis cussed. Expect more illustrations than equations\, and in addition a coupl e of (interactive) live software demos!

\nFor further information ab out the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20210430T120000 END:VEVENT BEGIN:VEVENT UID:news1172@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210426T124049 DTSTART;TZID=Europe/Zurich:20210428T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Soeren Petrat (Jacobs Un iversity Bremen) DESCRIPTION:We consider the non-relativistic quantum dynamics of N bosons i n the mean-field scaling limit. It is known that the leading order behavi or is described by the Hartree equation\, and the next-to-leading order b y Bogoliubov theory. Here\, we prove a perturbative expansion around Bog oliubov theory: a norm approximation of the true solution to the Schroedi nger equation to any order in 1/N. The coefficients in the expansion are independent of N\, and can be computed from the solutions to the Hartree and Bogoliubov equations alone. Our expansion leads to approximations of correlation functions and reduced densities to any order in 1/N. In this sense we have completely solved the dynamics of this mean-field model\, a t least for bounded interaction potentials.\\r\\nThis is joint work with L ea Bossmann\, Peter Pickl\, and Avy Soffer. X-ALT-DESC:We consider the non-relativistic quantum dynamics of N bosons in the \;mean-field scaling limit. It is known that the leading order behavior is \;described by the Hartree equation\, and the next-to-lea ding order by \;Bogoliubov theory. Here\, we prove a perturbative expa nsion around \;Bogoliubov theory: a norm approximation of the true sol ution to the \;Schroedinger equation to any order in 1/N. The coeffici ents in the \;expansion are independent of N\, and can be computed fro m the solutions \;to the Hartree and Bogoliubov equations alone. Our e xpansion leads to \;approximations of correlation functions and reduce d densities to any \;order in 1/N. In this sense we have completely so lved the dynamics of \;this mean-field model\, at least for bounded in teraction potentials.

\nThis is joint work with Lea Bossmann\, Peter Pickl\, and Avy Soffer.

DTEND;TZID=Europe/Zurich:20210428T151500 END:VEVENT BEGIN:VEVENT UID:news1182@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210423T135637 DTSTART;TZID=Europe/Zurich:20210426T121500 SUMMARY:Bernoullis Tafelrunde: Enrico Giudice (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2846] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210426T130000 END:VEVENT BEGIN:VEVENT UID:news1167@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210627T202614 DTSTART;TZID=Europe/Zurich:20210423T110000 SUMMARY:Seminar in Numerical Analysis: Markus Melenk (TU Wien) DESCRIPTION:We consider the Helmholtz equation with piecewise analytic coef ficients at large wavenumber k > 0. The interface where the coefficients j ump is assumed to be analytic. We develop a k-explicit regularity theory f or the solution that takes the form of a decomposition into two components : the first component is a piecewise analytic\, but highly oscillatory fun ction and the second one has finite regularity but features wavenumber-ind ependent bounds. This decomposition generalizes earlier decompositions of [MS10\, MS11\, EM11\, MSP12]\, which considered the Helmholtz equation wit h constant coefficients\, to the case of (piecewise) analytic coefficients . This regularity theory allows to show for high order Galerkin discretiza tions (hp-FEM) of the Helmholtz equation that quasi-optimality is reached if (a) the approximation order p is selected as p = O(log k) and (b) the m esh size h is such that kh/p is sufficiently small. This extends the resul ts of [MS10\, MS11\, EM11\, MSP12] about the onset of quasi-optimality of hp-FEM for the Helmholtz equation to the case of the heterogeneous Helmhol tz equation.\\r\\nJoint work with: Maximilian Bernkopf (TU Wien)\, Théoph ile Chaumont-Frelet (Inria).\\r\\nReferences [EM11] S. Esterhazy and J.M. Melenk\, On stability of discretizations of the Helmholtz equation\, in: Numerical Analysis of Multiscale Problems\, Graham et al.\, eds\, Sp ringer 2012 [MS10] J.M. Melenk and S. Sauter\, Convergence Analysis f or Finite Element Discretizations of the Helmholtz equation with Dirichlet -to-Neumann boundary conditions\, Math. Comp. 79:1871–1914\, 2010 [MS11] J.M. Melenk and S. Sauter\, Wavenumber explicit convergence analysis for finite element discretizations of the Helmholtz equation\, SIAM J. Nu mer. Anal.\, 49:1210–1243\, 2011 [MSP12] J.M. Melenk\, S. Sauter\, A. Pa rsania\, Generalized DG-methods for highly indefinite Helmholtz problems\, J. Sci. Comp. 57:536–581\, 2013\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:We consider the Helmholtz equation with piecewise analytic co efficients at large wavenumber k >\; 0. The interface where the coeffici ents jump is assumed to be analytic. We develop a k-explicit regularity th eory for the solution that takes the form of a decomposition into two comp onents: the first component is a piecewise analytic\, but highly oscillato ry function and the second one has finite regularity but features wavenumb er-independent bounds. This decomposition generalizes earlier decompositio ns of [MS10\, MS11\, EM11\, MSP12]\, which considered the Helmholtz equati on with constant coefficients\, to the case of (piecewise) analytic coeffi cients. This regularity theory allows to show for high order Galerkin disc retizations (hp-FEM) of the Helmholtz equation that quasi-optimality is re ached if (a) the approximation order p is selected as p = O(log k) and (b) the mesh size h is such that kh/p is sufficiently small. This extends the results of [MS10\, MS11\, EM11\, MSP12] about the onset of quasi-optimali ty of hp-FEM for the Helmholtz equation to the case of the heterogeneous H elmholtz equation.

\nJoint work with: Maximilian Bernkopf (TU Wien)\ , Théophile Chaumont-Frelet (Inria).

\n**References**<
br /> [EM11] \; \; \;S. Esterhazy and J.M. Melenk\, On stabil
ity of discretizations of the Helmholtz equation\, in: Numerical \;Ana
lysis of Multiscale Problems\, Graham et al.\, eds\, Springer 2012

[
MS10] \; \;J.M. Melenk and S. Sauter\, Convergence Analysis for
Finite Element Discretizations of the Helmholtz equation with Dirichlet-to
-Neumann boundary conditions\, Math. Comp. 79:1871–1914\, 2010

[MS
11] \; \;J.M. Melenk and S. Sauter\, Wavenumber explicit converg
ence analysis for finite element discretizations of the Helmholtz equation
\, SIAM J. Numer. Anal.\, 49:1210–1243\, 2011

[MSP12] J.M. Melenk\
, S. Sauter\, A. Parsania\, Generalized DG-methods for highly indefinite H
elmholtz problems\, J. Sci. Comp. 57:536–581\, 2013

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20210423T120000 END:VEVENT BEGIN:VEVENT UID:news1181@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210419T094722 DTSTART;TZID=Europe/Zurich:20210419T121500 SUMMARY:Bernoullis Tafelrunde: Mani Esna-Ashari (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2841] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210419T130000 END:VEVENT BEGIN:VEVENT UID:news1154@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210627T202454 DTSTART;TZID=Europe/Zurich:20210416T110000 SUMMARY:Seminar in Numerical Analysis: Guy Gilboa (Technion - Israel Instit ute of Technology) DESCRIPTION:Recent studies on nonlinear eigenvalue problems show surprising analogies to harmonic analysis (e.g. Fourier or wavelets). In this talk we first show the total-variation (TV) transform\, based on the TV gradien t flow\, and its application in image processing. We then present new resu lts on analyzing gradient flows of homogeneous nonlinear operators (such a s the p-Laplacian). Our framework allows a thorough investigation of Dynam ic-Mode-Decomposition (DMD)\, a central dimensionality reduction method fo r time series data. We present analytic solutions of simple nonlinear case s\, reveal shortcomings of DMD and propose improved decomposition methods. \\r\\nFor further information about the seminar\, please visit this webpag e [t3://page?uid=1115]. X-ALT-DESC:Recent studies on nonlinear eigenvalue problems show surprisi ng analogies to harmonic analysis (e.g. Fourier or wavelets). \;In thi s talk we first show the total-variation (TV) transform\, based on the TV gradient flow\, and its application in image processing. We then present n ew results on analyzing gradient flows of homogeneous nonlinear operators (such as the p-Laplacian). Our framework allows a thorough investigation o f Dynamic-Mode-Decomposition (DMD)\, a central dimensionality reduction me thod for time series data. We present analytic solutions of simple nonline ar cases\, reveal shortcomings of DMD and propose improved decomposition m ethods.

\nFor further information about the seminar\, please visit t his webpage.

DTEND;TZID=Europe/Zurich:20210416T120000 END:VEVENT BEGIN:VEVENT UID:news1168@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210413T143513 DTSTART;TZID=Europe/Zurich:20210413T170000 SUMMARY:Kick-off event: We Are Computer Science DESCRIPTION:The event is open to public and free using the registration lin k. [https://www.eventbrite.com/e/we-are-computer-science-association-kick- off-event-tickets-148803430065] X-ALT-DESC:The event is open to public and free using the registration link.

\n\n END:VEVENT BEGIN:VEVENT UID:news1180@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210409T174430 DTSTART;TZID=Europe/Zurich:20210412T121500 SUMMARY:Bernoullis Tafelrunde: Ahmed Hashem Abdelhameed Abouelsaad (Univers ität Basel) DESCRIPTION:abstract [t3://file?uid=2839] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210412T130000 END:VEVENT BEGIN:VEVENT UID:news1161@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210627T202314 DTSTART;TZID=Europe/Zurich:20210409T110000 SUMMARY:Seminar in Numerical Analysis: Barbara Kaltenbacher (Universität K lagenfurt) DESCRIPTION:High intensity (focused) ultrasound HIFU is used in numerous me dical and industrial applications ranging from litotripsy and thermotherap y via ultrasound cleaning and welding to sonochemistry. In this talk\, we will highlight two computational aspects related to the relevant nonlinea r acoustic phenomena\, namely\\r\\n absorbing boundary conditions for the treatment of open domain problems\; optimization tasks for ultrasound fo cusing. \\r\\nStrictly speaking\, acoustic sound propagation takes place i n full space or at least in a domain that is typically much larger than th e region of interest Ω. To restrict attention to a bounded domain Ω\, e. g\, for computational purposes\, artificial reflections on the boundary ∂Ω have to be avoided. This can be done by imposing so-called absorbin g boundary conditions ABC that induce dissipation of outgoing waves. Here it will turn out to be crucial to take into account nonlinearity of the PD E also in these ABC. This is joint work with Igor Shevchenko (Imperial Co llege London). In the context of applications in HIFU\, focusing of nonli nearly propagating waves amounts to optimization problems. The design of u ltrasound excitation via piezoelectric transducers leads to a boundary con trol problem\; focusing high intensity ultrasound by a silicone lens requi res shape optimization. For both problem classes\, we will discuss the der ivation of gradient information in order to formulate optimality condition s and drive numerical optimization methods. This is joint work with Chris tian Clason (University of Duisburg-Essen)\, Vanja Nikolić (TU München) \, and Gunther Peichl (University of Graz). Finally we will provide an ou tlook on imaging with nonlinearly acoustic waves\, which amounts to identi fying spatially varying coefficients (sound speed and/or coefficient of nonlinearity) in the Westervelt equation. This is recent joint work with Masahiro Yamamoto (University of Tokyo) and William Rundell (Texas A&M Uni versity).\\r\\nFor further information about the seminar\, please visit th is webpage [t3://page?uid=1115]. X-ALT-DESC:High intensity (focused) ultrasound HIFU is used in numerous medical and industrial applications ranging from litotripsy and thermother apy via ultrasound cleaning and welding to sonochemistry. \;In this ta lk\, we will highlight two computational aspects related to the relevant n onlinear acoustic phenomena\, namely

\n- absorbing boundary con ditions for the treatment of open domain problems\;
- optimization tasks for ultrasound focusing.

Strictly speaking\, acousti
c sound propagation takes place in full space or at least in a domain that
is typically much larger than the region of interest Ω. To restrict atte
ntion to a bounded domain Ω\, e.g\, for computational purposes\, artifici
al reflections on the boundary ∂Ω \;have to be avoided. This can be
done by imposing so-called absorbing boundary conditions ABC that induce
dissipation of outgoing waves. Here it will turn out to be crucial to take
into account nonlinearity of the PDE also in these ABC. \;This is joi
nt work with Igor Shevchenko (Imperial College London).

In th
e context of applications in HIFU\, focusing of nonlinearly propagating wa
ves amounts to optimization problems. The design of ultrasound excitation
via piezoelectric transducers leads to a boundary control problem\; focusi
ng high intensity ultrasound by a silicone lens requires shape optimizatio
n. For both problem classes\, we will discuss the derivation of gradient i
nformation in order to formulate optimality conditions and drive numerical
optimization methods. \;This is joint work with Christian Clason (Uni
versity of Duisburg-Essen)\, Vanja Nikolić \;(TU München)\, and Gunt
her Peichl (University of Graz).

Finally we will provide an o
utlook on imaging with nonlinearly acoustic waves\, which amounts to ident
ifying \; spatially varying coefficients (sound speed and/or coefficie
nt of nonlinearity) in the Westervelt equation. \;This is recent joint
work with Masahiro Yamamoto (University of Tokyo) and William Rundell (Te
xas A&\;M University).

For further information about the semina r\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20210409T120000 END:VEVENT BEGIN:VEVENT UID:news1162@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210316T094354 DTSTART;TZID=Europe/Zurich:20210407T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Jules Pitcho (University of Zurich) DESCRIPTION:The recent work of Brué\, Colombo and De Lellis has establishe d that\, for Sobolev vector fields\, the continuity equation may be well-p osed in a Lagrangian sense\, yet trajectories of the associated ODE need n ot be unique. We describe how a convex integration scheme for the continui ty equation reveals these degenerate integral curves\; we modify this sche me to produce Sobolev vector fields for which “most” integral curves a re degenerate. More precisely\, we produce Sobolev vector fields which hav e any finite number of integral curves starting almost everywhere. This is a joint work with Massimo Sorella. X-ALT-DESC:The recent work of Brué\, Colombo and De Lellis has establis hed that\, for Sobolev vector fields\, the continuity equation may be well -posed in a Lagrangian sense\, yet trajectories of the associated ODE need not be unique. We describe how a convex integration scheme for the contin uity equation reveals these degenerate integral curves\; we modify this sc heme to produce Sobolev vector fields for which “most” integral curves are degenerate. More precisely\, we produce Sobolev vector fields which h ave any finite number of integral curves starting almost everywhere. This is a joint work with Massimo Sorella. \;

DTEND;TZID=Europe/Zurich:20210407T160000 END:VEVENT BEGIN:VEVENT UID:news1177@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210330T104607 DTSTART;TZID=Europe/Zurich:20210406T181500 SUMMARY:Computer Science and Ethics DESCRIPTION:Die Ringvorlesung «Künstliche Intelligenz im Recht» beleucht et ethische und rechtliche Folgeprobleme des Einsatzes von KI aus verschie denen Fachperspektiven.\\r\\n Eröffnung der Ringvorlesung: Prof. Dr. Wo lfgang Wohlers\, Dekan der Juristischen Fakultät\, und Prof. Dr. Bijan Fateh-Moghadam\, Leiter des Doktoratsprogramms «Recht im Wandel» Könn en wir Künstlicher Intelligenz vertrauen? Prof. Dr. Malte Helmert\, Profe ssor für Informatik\, Universität Basel Intelligente Maschinen als mor alische Akteure: Lukas Brand\, Doktorand am Lehrstuhl für Religionsphil osophie und Wissenschaftstheorie\, Bochum \\r\\nModeration: Prof. Dr. Bij an Fateh-Moghadam\, Universität Basel\\r\\nRegistrierung\\r\\nDie Vorlesu ngsreihe wird digital durchgeführt. Für die Teilnahme an der öffentlic hen Ringvorlesung ist eine Registrierung [https://unibas.zoom.us/webinar/r egister/WN_4Ii0CzRJRw6S1lJKn2C6mw] erforderlich. Danach erhalten Sie eine Bestätigungs-E-Mail mit Informationen zur Teilnahme am Webinar.\\r\\nVera nstalter: Juristische Fakultät\\r\\nDie Veranstaltung findet in deutscher Sprache statt. X-ALT-DESC:Die Ringvorlesung «Künstliche Intelligenz im Recht» beleuc htet ethische und rechtliche Folgeprobleme des Einsatzes von KI aus versch iedenen Fachperspektiven.

\n**Eröffnung der Ringvorles ung:**\;Prof. Dr. Wolfgang Wohlers\, Dekan der \;Juristisc hen Fakultät\, und \;Prof. Dr. Bijan Fateh-Moghadam\, Leiter des \;Doktoratsprogramms «Recht im Wandel»**Können wir Kü nstlicher Intelligenz vertrauen?**Prof. Dr. Malte Helmert\, Profes sor für \;Informatik\, Universität Basel**Intellige nte Maschinen als moralische Akteure:**\;Lukas Brand\, Doktora nd am \;Lehrstuhl für Religionsphilosophie und Wissenschaftstheorie\, \;Bochum

Moderation: Prof. Dr. Bijan Fateh-Moghadam\, Universität Basel

\nDie Vorlesungsreihe wir d digital durchgeführt. \;Für die Teilnahme an der öffentlichen Rin gvorlesung ist eine Registrierung erforderlich. Danach erhalten Sie eine Bestätigungs-E-Mail mit Informationen zur Teilnahme am Webinar.

\ n**Veranstalter:**

Juristische Fakultät

The talk is open to members of the university.

\nFor th e access link\, please contact Prof. Gianluca Crippa (gianluca.crippa@unib as.ch).

END:VEVENT BEGIN:VEVENT UID:news1150@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210409T093405 DTSTART;TZID=Europe/Zurich:20210329T121500 SUMMARY:Bernoullis Tafelrunde: Merlin Fallahpour (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2795] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20210329T130000 END:VEVENT BEGIN:VEVENT UID:news1138@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210318T140108 DTSTART;TZID=Europe/Zurich:20210324T140000 SUMMARY:Seminar Analysis and Mathematical Physics: Jonas Lampart (CNRS\, LI CB) DESCRIPTION:I will discuss some properties of the set of all trajectories t hat can be obtained from a fixed initial state by varying the potential in the Schrödinger equation. This is related to the control problem\, i.e. driving the system to a target state\, which turns out to be impossible fo r "typical" target states using bounded potentials. X-ALT-DESC:I will discuss some properties of the set of all trajectories
that can be obtained from a fixed initial state by varying the potential
in the Schrödinger equation.

This is related to the control problem
\, i.e. driving the system to a target state\, which turns out to be impos
sible for "typical" target states using bounded potentials.

**17:00-17:
45** \; Presentation**18:00-18:45** \;
Open consultation**19:00-19:45** \; Open consultat
ion

**17:00-18:00 \; Open consultation 18:00-18:45 \; P
resentation18:45-20:00 \; Open consultation**

**17:00-17:45 \; Presentation\, open consultation (I) 18:00-18:4
5 \; Meet our Students19:00-19:45&nbs
p\; Presentation\, open consultation (II)**

For more information\, go to the website of the Basel Master’s info evening.

\n< p>The links to the events will be published here on March 17th. DTEND;TZID=Europe/Zurich:20210318T200000 END:VEVENT BEGIN:VEVENT UID:news1141@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210223T224755 DTSTART;TZID=Europe/Zurich:20210317T140000 SUMMARY:Seminar Analysis and Mathematical Physics: Alessandro Olgiati (Univ ersity of Zurich) DESCRIPTION:We study the ground state properties of a system of bosonic par ticles trapped by a double-well potential\, in the limit of large inter-we ll separation and of high potential barrier. The N bosons also interact vi a a mean-field two-body potential\, in the limit of large N.The leading-or der physics is governed by a Bose-Hubbard Hamiltonian coupling two low-ene rgy modes\, each supported in the bottom of one well. Fluctuations beyond these two modes are ruled by two independent Bogoliubov Hamiltonians\, one for each well.Our main result is that the variance of the number of parti cles in the low-energy modes is suppressed. This is a violation of the Cen tral Limit Theorem which holds in the occurrence of Bose-Einstein condensa tion\, and therefore it signals that particles develop correlations in the ground state. We achieve our result by proving a precise energy expansion in term of Bose-Hubbard and Bogoliubov energies.Joint work with Nicolas R ougerie (ENS Lyon) and Dominique Spehner (Universidad de Concepción). X-ALT-DESC:We study the ground state properties of a system of bosonic part icles trapped by a double-well potential\, in the limit of large inter-wel l separation and of high potential barrier. The N bosons also interact via a mean-field two-body potential\, in the limit of large N.The leadi ng-order physics is governed by a Bose-Hubbard Hamiltonian coupling two lo w-energy modes\, each supported in the bottom of one well. Fluctuations be yond these two modes are ruled by two independent Bogoliubov Hamiltonians\ , one for each well.

Our main result is that the variance of the numb er of particles in the low-energy modes is suppressed. This is a violation of the Central Limit Theorem which holds in the occurrence of Bose-Einste in condensation\, and therefore it signals that particles develop correlat ions in the ground state. We achieve our result by proving a precise energ y expansion in term of Bose-Hubbard and Bogoliubov energies.

Joint wo rk with Nicolas Rougerie (ENS Lyon) and Dominique Spehner (Universidad de Concepción). DTEND;TZID=Europe/Zurich:20210317T160000 END:VEVENT BEGIN:VEVENT UID:news1149@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210226T114306 DTSTART;TZID=Europe/Zurich:20210315T121500 SUMMARY:Bernoullis Tafelrunde: Ioanna Motschan (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2793] X-ALT-DESC:abstract DTEND;TZID=Europe/Zurich:20210315T130000 END:VEVENT BEGIN:VEVENT UID:news1155@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210303T084911 DTSTART;TZID=Europe/Zurich:20210304T143000 SUMMARY:PhD Defense Computer Science: Ahmed Hamdy Mohamed Eleliemy DESCRIPTION:Scientists are eager to utilize computing resources to execute scientific applications to advance the understanding of various complex ph enomena. This eagerness drives rapid technological developments in high pe rformance computing (HPC). Modern HPC systems exhibit rapid growth in the number of cores per computing node and the number of computing nodes per s ystem. As such\, modern HPC systems offer additional levels of hardware pa rallelism at the core\, node\, and system levels. Each level requires and employs techniques for appropriate scheduling of the computational work at the respective level. These scheduling techniques work separately without coordination. Hence\, each technique is designed to achieve specific perf ormance targets. Currently\, the absence of coordination between scheduler s at different levels is an open research problem. In many cases\, indepen dent scheduling decisions degrade applications’ performance and signify inefficient resource usage of contemporary HPC systems. To solve this prob lem\, this doctoral dissertation formulates an important research question : How can scheduling exploit the multilevel of hardware parallelism of mod ern HPC systems to enhance scientific applications’ performance and incr ease utilization of HPC resources?\\r\\nUnderstanding the relation between different scheduling levels is crucial for solving the aforementioned res earch question. However\, it is challenging due to (1) the absence of meth ods\, models\, and tools to examine and analyze the interaction and the mu tual impact of these scheduling levels\, and (2) the different nature and performance targets of each of these scheduling levels. This doctoral diss ertation addresses these challenges in the context of two specific HPC sch eduling classes: queuing-based job scheduling at the batch level and dynam ic loop self-scheduling (DLS) at the application level. One of the main co ntributions of this doctoral dissertation is proposing and evaluating a mu ltilevel scheduling (MLS) prototype that effectively solves the problem by bridging the schedulers at different scheduling levels. The MLS prototype aims to (1) decrease applications’ execution time and (2) increase syst em utilization. The MLS prototype employs two novel scheduling approaches introduced in this doctoral dissertation. The first approach is the distri buted chunk calculation approach (DCA) and its hierarchical version (HDCA) . The second approach is the resourceful coordination approach (RCA).\\r\\ nAt the application level\, the DCA and HDCA address the scalability chall enge of existing DLS implementations. We apply DCA and HDCA to several sta te-of-the-art DLS techniques\, and show how they benefit applications’ e xecution time\; therefore\, fulfilling the MLS prototype’s first target. At the batch level\, the RCA enables application schedulers to share thei r allocated but idle computing resources with other applications through a batch system. The significance of RCA is that it leverages and combines t he advantages of node sharing and dynamic resource management. It offers e fficient resource sharing and avoids shrinkage and expansion operations at the application side. RCA allows batch systems to reassign computing reso urces once they become free\; therefore\, fulfilling the MLS prototype’s second target. By employing DCA and RCA\, the MLS prototype answers the a forementioned research question and shows a creative and useful way for ex ploiting the multilevel parallelism of modern HPC systems through scheduli ng.\\r\\nThis doctoral dissertation advances the state-of-the-art by demon strating the usefulness and the performance potential of coordinated sched uling decisions at different levels. Moreover\, this doctoral dissertation introduces certain methods and tools that allow the HPC community to anal yze the mutual impact of scheduling decisions at different scheduling leve ls.\\r\\nThe talk is open to members of the university.\\r\\nFor the acces s link\, please contact Prof. Florina Ciorba (florina.ciorba@unibas.ch). X-ALT-DESC:

Scientists are eager to utilize computing resources to execut e scientific applications to advance the understanding of various complex phenomena. This eagerness drives rapid technological developments in high performance computing (HPC). Modern HPC systems exhibit rapid growth in th e number of cores per computing node and the number of computing nodes per system. As such\, modern HPC systems offer additional levels of hardware parallelism at the core\, node\, and system levels. Each level requires an d employs techniques for appropriate scheduling of the computational work at the respective level. These scheduling techniques work separately witho ut coordination. Hence\, each technique is designed to achieve specific pe rformance targets. Currently\, the absence of coordination between schedul ers at different levels is an open research problem. In many cases\, indep endent scheduling decisions degrade applications’ performance and signif y inefficient resource usage of contemporary HPC systems. To solve this pr oblem\, this doctoral dissertation formulates an important research questi on: How can scheduling exploit the multilevel of hardware parallelism of m odern HPC systems to enhance scientific applications’ performance and in crease utilization of HPC resources?

\nUnderstanding the relation be tween different scheduling levels is crucial for solving the aforementione d research question. However\, it is challenging due to (1) the absence of methods\, models\, and tools to examine and analyze the interaction and t he mutual impact of these scheduling levels\, and (2) the different nature and performance targets of each of these scheduling levels. This doctoral dissertation addresses these challenges in the context of two specific HP C scheduling classes: queuing-based job scheduling at the batch level and dynamic loop self-scheduling (DLS) at the application level. One of the ma in contributions of this doctoral dissertation is proposing and evaluating a multilevel scheduling (MLS) prototype that effectively solves the probl em by bridging the schedulers at different scheduling levels. The MLS prot otype aims to (1) decrease applications’ execution time and (2) increase system utilization. The MLS prototype employs two novel scheduling approa ches introduced in this doctoral dissertation. The first approach is the d istributed chunk calculation approach (DCA) and its hierarchical version ( HDCA). The second approach is the resourceful coordination approach (RCA).

\nAt the application level\, the DCA and HDCA address the scalabili ty challenge of existing DLS implementations. We apply DCA and HDCA to sev eral state-of-the-art DLS techniques\, and show how they benefit applicati ons’ execution time\; therefore\, fulfilling the MLS prototype’s first target. At the batch level\, the RCA enables application schedulers to sh are their allocated but idle computing resources with other applications t hrough a batch system. The significance of RCA is that it leverages and co mbines the advantages of node sharing and dynamic resource management. It offers efficient resource sharing and avoids shrinkage and expansion opera tions at the application side. RCA allows batch systems to reassign comput ing resources once they become free\; therefore\, fulfilling the MLS proto type’s second target. By employing DCA and RCA\, the MLS prototype answe rs the aforementioned research question and shows a creative and useful wa y for exploiting the multilevel parallelism of modern HPC systems through scheduling.

\nThis doctoral dissertation advances the state-of-the-a rt by demonstrating the usefulness and the performance potential of coordi nated scheduling decisions at different levels. Moreover\, this doctoral d issertation introduces certain methods and tools that allow the HPC commun ity to analyze the mutual impact of scheduling decisions at different sche duling levels.

\n**The talk is open to members of the universi
ty.**

**For the access link\, please contact Prof. Fl
orina Ciorba (florina.ciorba@unibas.ch).**

Abstract: The derivation of effective descriptions from micro scopic \; \; \; \; \; \;dynamics is a very vivid a rea in mathematical physics. In the talk I \; \; \; \;&nbs p\; \;will discuss a system of many particles with Newtonian time evol ution \; \; \; \; \; \;that are subject to interac tion. It is well known that in the weak \; \; \; \; \; \;coupling limit this system converges\, under smoothness assumption on \; \; \; \; \; \;the interaction force\, to a s olution of the Vlasov equation. \; \; \; \;Weakening the t ypes of convergence (convergence for all initial \; \; \; \; \; \;conditions ->\; convergence in probability ->\; conver gence in \; \; \; \; \; \;distribution) the smooth ness condition on the interaction can be \; \; \; \; \ ; \;generalized. In the talk I will present recent results in this&nbs p\; \; \; \; \; \;direction and explain\, which types of convergence hold/do not hold \; \; \; \; \; \;u nder the different assumptions on the interaction force.

DTEND;TZID=Europe/Zurich:20210303T161500 END:VEVENT BEGIN:VEVENT UID:news1135@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210114T134540 DTSTART;TZID=Europe/Zurich:20210113T160000 SUMMARY:Info-Event: Bachelor's degree in Mathematics or Computer Science DESCRIPTION:On top of the information day of the University of Basel\, the Department of Mathematics and Computer Science is offering an additional i nformation event:\\r\\nhelp desk Mathematicshelp desk Computer Sciencemeet the Mathematics and Computer Science student group meet the We Are Comput er Science Associationdiscover research groups and focal points\\r\\nPupil s who are interested in the bachelor's degree in mathematics and/or comput er science are cordially invited to participate. X-ALT-DESC:On top of the information day of the University of Basel\, th e Department of Mathematics and Computer Science is offering an additional information event:

\n- help desk Mathematics
- help desk C omputer Science
- meet the Mathematics and Computer Science student group
- meet the We Are Computer Science Association
- discov er research groups and focal points

Pupils who are intereste d in the bachelor's degree in mathematics and/or computer science are cord ially invited to participate.

DTEND;TZID=Europe/Zurich:20210113T180000 END:VEVENT BEGIN:VEVENT UID:news1133@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210106T131600 DTSTART;TZID=Europe/Zurich:20210107T090000 SUMMARY:Bachelor Info Event DESCRIPTION:Find out more about the diverse range of courses at the Univers ity of Basel. The online information market on Thursday\, January 7th offe rs you in-depth insights and lots of information about the courses and sub jects.\\r\\nFurther information and links to the individual events can be found here [https://www.unibas.ch/de/Aktuell/-Veranstaltungen/Basler-Infot ag-Bachelor-2021.html] (in german). X-ALT-DESC:Find out more about the diverse range of courses at the Unive rsity of Basel. The online information market on Thursday\, January 7th of fers you in-depth insights and lots of information about the courses and s ubjects.

\nFurther information and links to the individual events ca
n be found **here** (in german).

The problem of maximal regularity in Lebesgue spaces is a hea vily studied question for linear PDEs that dates back to Calderón and Zyg mund for the Poisson equation and the potential theoretic approach develop ed by Ladyzhenskaya et al for the heat equation\, and represents the corne rstone in the analysis of many nonlinear PDEs. After a brief overview of t he linear theory\, in this talk I will focus on maximal L^q-regularity for viscous Hamilton-Jacobi equations with superlinear first order terms. I w ill first survey on recent results obtained for the stationary equation\, which answer positively to a conjecture raised by P.-L. Lions\, via a Bern stein-type argument. Then\, I will discuss Lipschitz and optimal L^q-regul arity for parabolic Hamilton-Jacobi equations that instead are tackled thr ough a refinement of the Evans’ nonlinear adjoint method\, thus exploiti ng fine regularity properties for advection-diffusion equations with “ro ugh” drifts\, providing new regularity results for systems of PDEs arisi ng in the theory of Mean Field Games. These are joint works with Marco Cir ant (Padova). \;

DTEND;TZID=Europe/Zurich:20201216T160000 END:VEVENT BEGIN:VEVENT UID:news1114@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201207T084253 DTSTART;TZID=Europe/Zurich:20201214T121500 SUMMARY:Bernoullis Tafelrunde: Philipp Mekler (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2755] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20201214T130000 END:VEVENT BEGIN:VEVENT UID:news1127@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210623T193706 DTSTART;TZID=Europe/Zurich:20201211T110000 SUMMARY:Seminar in Numerical Analysis: Heiko Gimperlein (Heriot-Watt Univer sity) DESCRIPTION:Diffusion processes beyond Brownian motion have recently attrac ted significant interest from different communities in mathematics\, the p hysical and biological sciences. They are described by partial differentia l equations involving nonlocal operators with singular non-integrable kern els\, such as fractional Laplacians. This talk discusses the challenges of their approximation by finite elements and discusses our recent results o n the a priori analysis of h\, p and hp-versions for the integral fraction al Laplacian\, as well as their preconditioning. \\r\\nFor further inform ation about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Diffusion processes beyond Brownian motion have recently attr acted significant interest from different communities in mathematics\, the physical and biological sciences. They are described by partial different ial equations involving nonlocal operators with singular non-integrable ke rnels\, such as fractional Laplacians. This talk discusses the challenges of their approximation by finite elements and discusses our recent results on the a priori analysis of h\, p and hp-versions for the integral fracti onal Laplacian\, as well as their preconditioning. \;

\nFor furt her information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20201211T120000 END:VEVENT BEGIN:VEVENT UID:news1131@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201208T113936 DTSTART;TZID=Europe/Zurich:20201210T173000 SUMMARY:Question and Answer Session with Turing Award Winner Leslie Lamport DESCRIPTION:As part of the Computer Science Bachelor seminar "Turing Award Winners and Their Contributions"\, the section of Computer Science is orga nizing a one-hour question and answer session with Turing Award Winner Les lie Lamport. The event is not limited to the seminar participants. All mem bers of the department\, especially students at all stages of their educat ion\, are more than welcome to join!\\r\\nLeslie Lamport received the Turi ng Award in 2013. The award citation reads "for fundamental contributions to the theory and practice of distributed and concurrent systems\, notably the invention of concepts such as causality and logical clocks\, safety a nd liveness\, replicated state machines\, and sequential consistency". In addition to these core scientific contributions\, he is also famous for in venting the LaTeX documentation preparation system.\\r\\nIn this Q&A sessi on\, we will ask him about his technical contributions and their impact\, his views on the past\, present and future of computer science\, and his t houghts on scientific writing and life as a researcher. The session uses a moderated format and is based primarily on questions provided by the semi nar participants. There will be an opportunity for the audience to ask liv e questions at the end. X-ALT-DESC:As part of the Computer Science Bachelor seminar "\;Turin g Award Winners and Their Contributions"\;\, the section of Computer S cience is organizing a one-hour question and answer session with Turing Aw ard Winner Leslie Lamport. The event is not limited to the seminar partici pants. All members of the department\, especially students at all stages o f their education\, are more than welcome to join!

\nLeslie Lamport received the Turing Award in 2013. The award citation reads "\;for fun damental contributions to the theory and practice of distributed and concu rrent systems\, notably the invention of concepts such as causality and lo gical clocks\, safety and liveness\, replicated state machines\, and seque ntial consistency"\;. In addition to these core scientific contributio ns\, he is also famous for inventing the LaTeX documentation preparation s ystem.

\nIn this Q&\;A session\, we will ask him about his techni cal contributions and their impact\, his views on the past\, present and f uture of computer science\, and his thoughts on scientific writing and lif e as a researcher. The session uses a moderated format and is based primar ily on questions provided by the seminar participants. There will be an op portunity for the audience to ask live questions at the end.

DTEND;TZID=Europe/Zurich:20201210T183000 END:VEVENT BEGIN:VEVENT UID:news1126@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201122T211830 DTSTART;TZID=Europe/Zurich:20201209T150000 SUMMARY:Seminar Analysis and Mathematical Physics: Mickaël Latocca (ENS Pa ris) DESCRIPTION:The possible growth of the Sobolev norms of the solution to the 2d (and 3d) Euler equations and its quantification remains ill-known. Th e only general bound is double exponential. Conversely\, such a double e xponential growth scenario occurs for specific initial data in the settin g of the disc (Kiselev-Sverak). In the setting of the torus\, only an exp onentially growing scenario has been exhibited (Zlatos). Could the double exponential scenario occur on the torus? What is the typical behaviour t hat could be expected? It is highly possible that on the torus\, Sobolev norms generically do not grow fast.In this talk\, I will present some resu lts obtained in this direction. We will construct invariant measures for the 2d Euler equation at high regularity ($H^s$\, $s>2$) and prove that o n the support of the measure\, Sobolev norms do not grow faster than poly nomially.Refining the method allows to construct an invariant measure to t he 3d Euler equations at high regularity ($H^s$\, $s>7/2$) and thus const ructglobal dynamics on the support of the measure\, exhibiting at most po lynomial growth.Finally\, it time permits we will discuss the properties o f the measures constructed. X-ALT-DESC:The possible growth of the Sobolev norms of the solution to the& nbsp\;2d (and 3d) Euler equations and its quantification remains ill-known . The \;only general bound is double exponential. Conversely\, such a double \;exponential growth scenario occurs for specific initial data in the \;setting of the disc (Kiselev-Sverak). In the setting of the t orus\, only an \;exponentially growing scenario has been exhibited (Zl atos). Could the \;double exponential scenario occur on the torus? Wha t is the typical \;behaviour that could be expected? It is highly poss ible that on the torus\, \;Sobolev norms generically do not grow fast.In this talk\, I will present some results obtained in this di rection. We \;will construct invariant measures for the 2d Euler equat ion at high \;regularity ($H^s$\, $s>\;2$) and prove that on the sup port of the measure\, \;Sobolev norms do not grow faster than polynomi ally.

Refining the method allows to construct an invariant meas ure to the 3d \;Euler equations at high regularity ($H^s$\, $s>\;7/2 $) and thus construct

global dynamics on the support of the measure\, exhibiting at most \;polynomial growth.

Finally\, it time permits we will discuss the properties of the measures \;constructed. DTEND;TZID=Europe/Zurich:20201209T160000 END:VEVENT BEGIN:VEVENT UID:news1106@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201116T100656 DTSTART;TZID=Europe/Zurich:20201209T140000 SUMMARY:Seminar Analysis and Mathematical Physics: Lea Bossmann (IST Austri a) DESCRIPTION:Abstract. \\r\\nWe consider a system of N bosons in the mean-f ield scaling regime in an external trapping potential. We derive an asymp totic expansion of the low-energy eigenstates and the corresponding ener gies\, which provides corrections to Bogoliubov theory to any order in 1/ N. We show that the structure of the ground state and of the non-degenera te low-energy eigenstates is preserved by the dynamics ifthe external trap is switched off. This talk is based on joint works with Sören Petrat\, Peter Pickl\, Robert Seiringer\, and Avy Soffer (arXiv:1912.11004 and arX iv:2006.09825). X-ALT-DESC:

Abstract. \;

\nWe consider a system of N bosons in
the mean-field scaling \;regime in an external trapping potential. We
derive an asymptotic \;expansion of the low-energy eigenstates and the
corresponding \;energies\, which provides corrections to Bogoliubov t
heory to any order \;in 1/N. We show that the structure of the ground
state and of the \;non-degenerate low-energy eigenstates is preserved
by the dynamics if

the external trap is switched off. This talk is ba
sed on joint works \;with Sören Petrat\, Peter Pickl\, Robert Seiring
er\, and Avy Soffer \;(arXiv:1912.11004 and arXiv:2006.09825).

We derive a simple criterion that ensures uniqueness\, Lipsch itz \;stability and global convergence of Newton's method for the fini te \;dimensional zero-finding problem of a continuously differentiable \, \;pointwise convex and monotonic function. Our criterion merely req uires \;to evaluate the directional derivative of the forward function at \;finitely many evaluation points and for finitely many directions .

\nWe then demonstrate that this result can be used to prove unique ness\, \;stability and global convergence for an inverse coefficient p roblem with \;finitely many measurements. We consider the problem of d etermining an \;unknown inverse Robin transmission coefficient in an e lliptic PDE. Using \;a relation to monotonicity and localized potentia ls techniques\, we show \;that a piecewise-constant coefficient on an a-priori known partition \;with a-priori known bounds is uniquely dete rmined by finitely many \;boundary measurements and that it can be uni quely and stably \;reconstructed by a globally convergent Newton itera tion. We derive a \;constructive method to identify these boundary mea surements\, calculate \;the stability constant and give a numerical ex ample.

\n

For further information about the seminar\, please v
isit this webpage.

Convex integration is a technique\, or rather a broad range o f techniques\, that originated in Nash's work on isometric embeddings of m anifolds in the 1950s. It serves to produce 'unexpected' solutions to vari ous geometric or analytic problems with peculiar behaviour. Convex integra tion has become very trendy again in the past ten years or so\, when it tu rned out that it surprisingly applies to the fundamental equations of flui d mechanics\, including the Euler and Navier-Stokes systems. Since contemp orary applications\, however\, have become increasingly technical\, it is often not easy to grasp the fundamental mechanism. I will attempt to prese nt this convex integration mechanism in a simple way\, and to discuss some applications to isometric embedding\, fluid dynamics\, and breakdown of t he chain rule for functions of low regularity.

END:VEVENT BEGIN:VEVENT UID:news1107@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201116T101053 DTSTART;TZID=Europe/Zurich:20201125T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Emanuela Giacomelli (LMU Munich) DESCRIPTION:Abstract: We consider N spin 1/2 fermions interacting wit h a positive and regular enough potential in three dimensions. We compute the ground state energy of the system in the dilute regime at second ord er in the particle density. We recover a well-know expression for the gro und state energy which depends on the interaction potentials only via its scattering length. A first proof of this result has been given by Lieb\, Seiringer and Solovej. We discuss a new derivation of this formula whic h makes use of the almost-bosonic nature of the low-energy excitations of the systems. Based on a joint work with Marco Falconi\, Christian Hain zl\, Marcello Porta. X-ALT-DESC:Abstract: \; \; \;

We consider N spin 1/2 f
ermions interacting with a positive \;

and regular enough potenti
al in three dimensions. We compute the ground \;

state energy of
the system in the dilute regime at second order in the \;

particl
e density. We recover a well-know expression for the ground state \;**energy which depends on the interaction potentials only via its \;
scattering length. A first proof of this result has been given by Li
eb\, \;Seiringer and Solovej. We discuss a new derivation of thi
s formula \;which \; makes use of the almost-bosonic nature
of the low-energy \;excitations of the systems. Based on a joint
work with Marco Falconi\, \;Christian Hainzl\, Marcello Porta.<
/p>
DTEND;TZID=Europe/Zurich:20201125T161500
END:VEVENT
BEGIN:VEVENT
UID:news1112@dmi.unibas.ch
DTSTAMP;TZID=Europe/Zurich:20201116T133110
DTSTART;TZID=Europe/Zurich:20201123T121500
SUMMARY:Bernoullis Tafelrunde: Raphael Erb (Universität Basel)
DESCRIPTION:abstract [t3://file?uid=2736]
X-ALT-DESC:**

We examine how time step adaptivity can be used to control&nb sp\;potential \;instability arising from \;non-Lipschitz \;ter ms \;for \;stochastic \;partial differential \;equations ( SPDEs). I will give a brief introduction to SPDEs and illustrate the stabi lity issue with the standard uniform step Euler method \;to \;moti vate the adaptive method. I \;will present a \;strong convergence& nbsp\;result and outline the \;steps of the proof. To illustrate the&n bsp\;method \;we \;examine the stochastic Allen-Cahn\, Swift-Hohen berg\, \; Kuramoto-Sivashinsky equations and finally will discuss a po tential use of the adaptivity for the deterministic system. This is joint work with Stuart Campbell.

DTEND;TZID=Europe/Zurich:20201120T120000 END:VEVENT BEGIN:VEVENT UID:news1093@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200915T131004 DTSTART;TZID=Europe/Zurich:20201119T170000 SUMMARY:PhD Defense Mathematics: Julia Schneider DESCRIPTION:The talk is open to members of the university. X-ALT-DESC:The talk is open to members of the university.

\n\n END:VEVENT BEGIN:VEVENT UID:news1108@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201116T132028 DTSTART;TZID=Europe/Zurich:20201116T121500 SUMMARY:Bernoullis Tafelrunde: Carina Santos (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2707] slides [t3://file?uid=2735] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20201116T130000 END:VEVENT BEGIN:VEVENT UID:news1102@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210623T193410 DTSTART;TZID=Europe/Zurich:20201113T110000 SUMMARY:Seminar in Numerical Analysis: Gilles Vilmart (Université de Genè ve) DESCRIPTION:We show that the Strang splitting method applied to a diffusion -reaction equation with inhomogeneous general oblique boundary conditions is of order two when the diffusion equation is solved with the Crank-Nic olson method\, while order reduction occurs in general if using other Ru nge-Kutta schemes or even the exact flow itself for the diffusion part. We also show that this method recovers stationary states in contrast with sp litting methods in general.We prove these results when the source term onl y depends on the space variable. Numerical experiments suggest that the s econd order of convergence persists with general nonlinearities.\\r\\nThi s is joint work with Guillaume Bertoli (Université de Genève) and Chris tophe Besse (Institut de Mathématiques de Toulouse).\\r\\nFor further inf ormation about the seminar\, please visit this webpage [t3://page?uid=111 5]. X-ALT-DESC:We show that the Strang splitting method applied to a diffusi on-reaction \;equation with inhomogeneous general oblique boundary con ditions is of \;order two when the diffusion equation is solved with t he Crank-Nicolson \;method\, while order reduction occurs in general i f using other \;Runge-Kutta schemes or even the exact flow itself for the diffusion part. We also show that this method recovers stationary stat es in contrast with splitting methods in general.We prove these results wh en the source term only depends on the space \;variable. Numerical exp eriments suggest that the second order of \;convergence persists with general nonlinearities.

\nThis is joint work with Guillaume Bertoli (Université de Genève) and \;Christophe Besse (Institut de Mathémat iques de Toulouse).

\nFor further information about the seminar\, pl ease visit this \;webpage.

DTEND;TZID=Europe/Zurich:20201113T120000 END:VEVENT BEGIN:VEVENT UID:news1100@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201102T110041 DTSTART;TZID=Europe/Zurich:20201111T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Lars Eric Hientzsch (Ins titut Fourier\, University of Grenoble Alpes) DESCRIPTION:The quantum Navier-Stokes (QNS) equations describe a compressib le fluid including a degenerate density dependent viscosity and a dispersi ve tensor accounting for capillarity effects. The system can be seen as vi scous correction of the Quantum Hydrodynamics (QHD) arising e.g. as protot ype model in the description of superfluidity. We consider the (QNS) syste m on the whole space with non-trivial farfield behaviour providing the sui table framework to study coherent structures and the incompressible limit. \\r\\nFirst\, we prove global existence of finite energy weak solutions (F EWS) in dimension two and three. To compensate for the lack of control of the velocity field around vacuum regions\, we construct approximate soluti ons to a truncated formulation of (QNS) on a sequence of invading domains. Suitable compactness properties are inferred from the Bresch-Desjadins en tropy estimates. This is joint work with P. Antonelli and S. Spirito.\\r\\ nSecond\, we address the low Mach number limit for FEWS to the (QNS) syste m (in collaboration with P. Antonelli and P. Marcati). The main novelty is a precise analysis of the acoustic dispersion altered by the presence of the dispersive capillarity tensor. The linearised system is governed by the Bogoliubov dispersion relation. The desired decay of the acoustic part follows from refined Strichartz estimates. X-ALT-DESC:The quantum Navier-Stokes (QNS) equations describe a compress ible fluid including a degenerate density dependent viscosity and a disper sive tensor accounting for capillarity effects. The system can be seen as viscous correction of the Quantum Hydrodynamics (QHD) arising e.g. as prot otype model in the description of superfluidity. We consider the (QNS) sys tem on the whole space with non-trivial farfield behaviour providing the s uitable framework to study coherent structures and the incompressible limi t.

\nFirst\, we prove global existence of finite energy weak solutio ns (FEWS) in dimension two and three. To compensate for the lack of contro l of the velocity field around vacuum regions\, we construct approximate s olutions to a truncated formulation of (QNS) on a sequence of invading dom ains. Suitable compactness properties are inferred from the Bresch-Desjadi ns entropy estimates. This is joint work with P. Antonelli and S. Spirito.

\nSecond\, we address the low Mach number limit for FEWS to the (QN S) system (in collaboration with P. Antonelli and P. Marcati). The main no velty is a precise analysis of the acoustic dispersion altered by the pres ence of the dispersive capillarity tensor. The \;linearised \;syst em is governed by the Bogoliubov dispersion relation. The desired decay of the acoustic part follows from refined Strichartz estimates. \;

DTEND;TZID=Europe/Zurich:20201111T160000 END:VEVENT BEGIN:VEVENT UID:news1119@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201116T160851 DTSTART;TZID=Europe/Zurich:20201109T121500 SUMMARY:Bernoullis Tafelrunde: Marta Dujella (Universität Basel) DESCRIPTION:abstract [t3://file?uid=2706] slides [t3://file?uid=2737] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20201109T130000 END:VEVENT BEGIN:VEVENT UID:news1036@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201024T154014 DTSTART;TZID=Europe/Zurich:20201104T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Marco Falconi (Universit y of Roma Tre) DESCRIPTION:Abstract. \\r\\nIn this talk I will overview variational proble ms arising from the study ofquantum matter interacting with a macroscopic force field. These interactions are verycommon in both solid state and con densed matter physics\, as well as in higher energysettings. In particular \, I will focus on the link between the effective and microscopicdescripti on of such variational problems\, using techniques of quasi-classical anal ysisdeveloped in recent years in collaboration with M. Correggi and M. Oli vieri. X-ALT-DESC:Abstract.

\nIn this talk I will overview variational p roblems arising from the study ofquantum matter interacting with a macrosc opic force field. These interactions are verycommon in both solid state an d condensed matter physics\, as well as in higher energysettings. In parti cular\, I will focus on the link between the effective and microscopicdesc ription of such variational problems\, using techniques of quasi-classical analysisdeveloped in recent years in collaboration with M. Correggi and M . Olivieri.

DTEND;TZID=Europe/Zurich:20201104T160000 END:VEVENT BEGIN:VEVENT UID:news1101@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20210623T193336 DTSTART;TZID=Europe/Zurich:20201030T110000 SUMMARY:Seminar in Numerical Analysis: Alfio Borzi (Universität Würzburg) DESCRIPTION:The Liouville equation is the fundamental building block of mod els that govern the evolution of density functions of multi-particle syst ems. These models include different Fokker-Planck and Boltzmann equations that arise in many application fields ranging from gas dynamics to pedes trians' motion where the need arises to control these systems.\\r\\nThis talk provides an introduction to the formulation and solution of optimal control problems governed by the Liouville equation and related models. T he purpose of this framework is the design of robust controls to steer th e motion of particles\, pedestrians\, etc.\, where these agents are repre sented in terms of density functions. For this purpose\, expected-value c ost functionals are considered that include attracting potentials and dif ferent costs of the controls\, whereas the control mechanism in the gover ning models is part of the drift or is included in a collision term.\\r\\ nIn this talk\, theoretical and numerical results concerning ensemble opt imal control problems with Liouville\, Fokker-Planck and linear Boltzmann equations are presented.\\r\\n For further information about the seminar\ , please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:The Liouville equation is the fundamental building block of m odels that \;govern the evolution of density functions of multi-partic le systems. These \;models include different Fokker-Planck and Boltzma nn equations that arise \;in many application fields ranging from gas dynamics to pedestrians' motion \;where the need arises to control the se systems.

\nThis talk provides an introduction to the formulation and solution \;of optimal control problems governed by the Liouville e quation \;and related models. The purpose of this framework \;is t he design of robust controls to steer the motion of particles\, pedestrian s\, etc.\, \;where these agents are represented in terms of density fu nctions. \;For this purpose\, expected-value cost functionals are cons idered \;that include attracting potentials and different costs of the controls\, whereas \;the control mechanism in the governing models is part of the drift \;or is included in a collision term.

\nIn th is talk\, theoretical and numerical results concerning ensemble \;opti mal control problems with Liouville\, Fokker-Planck and linear \;Boltz mann equations are presented.

\n

For further information about
the seminar\, please visit this webpage.

We propose an efficient algorithm for the treatment of Volter ra integral operators based on H2-matrix compression techniques. The algor ithm is built in an evolutionary manner\, and therefore\, is well suited f or the problems\, where the right hand side depends on the solution itself and is not known for all time steps a priori. The resulting algorithm is of linear complexity O(N) w.r.t. to the number of time steps\, and require s O(N) active memory. The memory consumption can be reduced to O(log N) fo r the kernels of convolution type using the Laplace inversion techniques i ntroduced by Lubich et al\; the connection to the FOCQ algorithm is drawn. We demonstrate the effectiveness of our algorithm on a series of numerica l examples.

\n

For further information about the seminar\, ple
ase visit this \;webpage.

The surface quasigeostrophic equation (SGQ) is a 2d physical model equation which emerges in meteorology. It has attracted the attentio n of the mathematical community since it shares many of the essential diff iculties of 3d fluid dynamics: in the supercritical regime for instance\, where dissipation is modelled by a fractional Laplacian of order less than 1/2\, it is not known whether or not smooth solutions blow-up in finite t ime. On the other hand\, the scheme of Leray still produces global-in-time weak solutions from any L^2-initial datum\, but their regularity is poorl y understood. In this talk\, I will propose a nonempty notion of "\;su itable weak solution"\; for the supercritical SQG equation and prove t hat those solutions are smooth outside a compact set of quantifiable Hausd orff dimension\; in particular they are smooth almost everywhere. I will a lso give a conjecture on what we believe to be an optimal dimension estima te. \;This is a joint work with Maria Colombo (EPFL).

DTEND;TZID=Europe/Zurich:20201014T160000 END:VEVENT BEGIN:VEVENT UID:news1088@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200923T091416 DTSTART;TZID=Europe/Zurich:20201007T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Klaus Widmayer (EPFL) DESCRIPTION:A point charge is a particularly basic and important equilibriu m of the Vlasov-Poisson equations\, and the study of its stability has ins pired several major contributions. In this talk we present some recent wor k\, which brings a fresh perspective on this problem. Our new approach com bines a Lagrangian analysis of the linearized problem with an Eulerian PDE framework in the nonlinear analysis\, all the while respecting the symple ctic structure. As a result\, for the case of radial initial data\, we see that solutions are global and in fact disperse to infinity via a modified scattering along trajectories of the linearized flow. This is joint work with Benoit Pausader (Brown University). X-ALT-DESC:A point charge is a particularly basic and important equilibr ium of the Vlasov-Poisson equations\, and the study of its stability has i nspired several major contributions. In this talk we present some recent w ork\, which brings a fresh perspective on this problem. Our new approach c ombines a Lagrangian analysis of the linearized problem with an Eulerian P DE framework in the nonlinear analysis\, all the while respecting the symp lectic structure. As a result\, for the case of radial initial data\, we s ee that solutions are global and in fact disperse to infinity via a modifi ed scattering along trajectories of the linearized flow. This is joint wor k with Benoit Pausader (Brown University).

DTEND;TZID=Europe/Zurich:20201007T160000 END:VEVENT BEGIN:VEVENT UID:news1095@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20201006T090928 DTSTART;TZID=Europe/Zurich:20201005T121500 SUMMARY:Bernoullis Tafelrunde: Martin Stoller (EPFL) DESCRIPTION:abstract [t3://file?uid=2646] slides [t3://file?uid=2677] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20201005T130000 END:VEVENT BEGIN:VEVENT UID:news1002@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200910T202733 DTSTART;TZID=Europe/Zurich:20200930T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Simone Dovetta (CNR-IMAT I\, Pavia) DESCRIPTION:The talk overviews some recent developments about nonlinear Sch roedinger equations (NLS) on metric graphs. Precisely\, we concentrate on variational problems for the NLS energy functional subject to the mass con straint. After a brief recap of the well-known behaviour of such model on the real line\, we address the existence of NLS ground states on noncompac t metric graphs\, with a specific focus on periodic graphs and infinite tr ees. The emergence of threshold phenomena rooted in the nature of these gr aphs is discussed. Finally\, we provide some insights on the uniqueness of ground states at fixed mass. On the one hand\, uniqueness is shown to hol d for two classes of graphs with halflines. On the other hand\, a countere xample to uniqueness in full generality is exhibited. The matter we discus s is part of a wider research line\, developed in collaboration with sever al authors. The results explicitly covered by the talk refer to a series o f papers\, some of which are joint works with Riccardo Adami\, Enrico Serr a and Paolo Tilli. X-ALT-DESC:The talk overviews some recent developments about nonlinear S chroedinger equations (NLS) on metric graphs. Precisely\, we concentrate o n variational problems for the NLS energy functional subject to the mass c onstraint. After a brief recap of the well-known behaviour of such model o n the real line\, we address the existence of NLS ground states on noncomp act metric graphs\, with a specific focus on periodic graphs and infinite trees. The emergence of threshold phenomena rooted in the nature of these graphs is discussed. Finally\, we provide some insights on the uniqueness of ground states at fixed mass. On the one hand\, uniqueness is shown to h old for two classes of graphs with halflines. On the other hand\, a counte rexample to uniqueness in full generality is exhibited. The matter we disc uss is part of a wider research line\, developed in collaboration with sev eral authors. The results explicitly covered by the talk refer to a series of papers\, some of which are joint works with Riccardo Adami\, Enrico Se rra and Paolo Tilli.

DTEND;TZID=Europe/Zurich:20200930T160000 END:VEVENT BEGIN:VEVENT UID:news1089@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200827T084304 DTSTART;TZID=Europe/Zurich:20200903T081500 SUMMARY:Symposium Data Analytics Systems DESCRIPTION:The event is open to all members of the University. X-ALT-DESC:The event is open to all members of the University.

DTEND;TZID=Europe/Zurich:20200903T160000 END:VEVENT BEGIN:VEVENT UID:news995@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200317T094345 DTSTART;TZID=Europe/Zurich:20200312T161500 SUMMARY:CANCELLED: Perlen-Kolloquium: Prof. Dr. Martin J. Gander (Universit é de Genève) DESCRIPTION:The Perlen-Kolloquium on March 12th is cancelled. \\r\\nItera tive methods for linear systems were invented for the same reasons as they are used today\, namely to reduce computational cost. Gauss states in a l etter to his friend Gerling in 1823: "you will in the future hardly elimin ate directly\, at least not when you have more than two unknowns". Richard son's paper from 1910 was then very influential\, and is a model of a mode rn numerical analysis paper: modeling\, discretization\, approximate solut ion of the discrete problem\, and a real application. More general vector extrapolation methods were then introduced and studied in the pioneering w ork of Bresinzki\, and they can be shown to be equivalent to Krylov method . It was however the work of Stiefel\, Hestenes and Lanczos in the early 1 950 that sparked the success story of Krylov methods with the invention of the conjugate gradient method\, and there are now many Krylov methods to choose from. For general linear systems\, they come in two main classes\, the ones that minimize the residual in a Krylov space\, and the ones that make the residual orthogonal to it. This will bring us finally to the mode rn iterative methods for solving partial differential equations\, which al so come in two main classes: domain decomposition methods and multigrid me thods. Domain decomposition methods go back to the alternating Schwarz met hod invented by Herman Amandus Schwarz in 1869 to close a gap in the proof of Riemann's famous Mapping Theorem. Multigrid goes back to the seminal w ork by Fedorenko in 1961\, with main contributions by Brandt and Hackbusch in the Seventies. X-ALT-DESC:**The Perlen-Kolloquium on March 12 ^{th} is cancelle
d.** \;

Iterative methods for linear systems were invented for the same reasons as they are used today\, namely to reduce computation al cost. Gauss states in a letter to his friend Gerling in 1823: "\;yo u will in the future hardly eliminate directly\, at least not when you hav e more than two unknowns"\;. Richardson's paper from 1910 was then ver y influential\, and is a model of a modern numerical analysis paper: model ing\, discretization\, approximate solution of the discrete problem\, and a real application. More general vector extrapolation methods were then in troduced and studied in the pioneering work of Bresinzki\, and they can be shown to be equivalent to Krylov method. It was however the work of Stief el\, Hestenes and Lanczos in the early 1950 that sparked the success story of Krylov methods with the invention of the conjugate gradient method\, a nd there are now many Krylov methods to choose from. For general linear sy stems\, they come in two main classes\, the ones that minimize the residua l in a Krylov space\, and the ones that make the residual orthogonal to it . This will bring us finally to the modern iterative methods for solving p artial differential equations\, which also come in two main classes: domai n decomposition methods and multigrid methods. Domain decomposition method s go back to the alternating Schwarz method invented by Herman Amandus Sch warz in 1869 to close a gap in the proof of Riemann's famous Mapping Theor em. Multigrid goes back to the seminal work by Fedorenko in 1961\, with ma in contributions by Brandt and Hackbusch in the Seventies.

\n\n END:VEVENT BEGIN:VEVENT UID:news1022@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200217T114353 DTSTART;TZID=Europe/Zurich:20200226T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Luigi De Rosa (EPF Lausa nne) DESCRIPTION:I will describe how convex integration techniques can be used t o show that wilddissipative solutions of the incompressible Euler equation s are typical in the Baire category sense. This also partially solves a co njecture by Philip Isett on the sharpness of the kinetic energy regularity for Hölder continuous solutions of the Euler equations. The talk will b e based on a recent work obtained in collaboration with Riccardo Tione. X-ALT-DESC:I will describe how convex integration techniques can be used to show that wilddissipative solutions of the incompressible Euler equati ons are typical in the Baire category sense. This also partially solves a conjecture by Philip Isett on the sharpness of the kinetic energy regulari ty \;for Hölder continuous solutions of the Euler equations. The talk will be based on a recent work obtained \;in collaboration with Ricca rdo Tione.

DTEND;TZID=Europe/Zurich:20200226T160000 END:VEVENT BEGIN:VEVENT UID:news1023@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200220T145956 DTSTART;TZID=Europe/Zurich:20200225T103000 SUMMARY:Seminar Algebra and Geometry: Anne Lonjou (Universität Basel) DESCRIPTION:A key tool to study the plane Cremona group is its action on a hyperbolic space. Saddly\, in higher rank such an action is not available. Recently in geometric group theory\, actions on CAT(0) cube complexes tur ned out to be a powerfull tool to study a large class of groups. \\r \\nIn this talk\, based on a common work with Christian Urech\, we will co nstruct such complexes on which Cremona groups of rank n act. We will then see which kind of results on these groups we can obtain. X-ALT-DESC:A key tool to study the plane Cremona group is its action on a hyperbolic space. Saddly\, in higher rank such an action is not availabl e. Recently in geometric group theory\, actions on CAT(0) cube complexes t urned out to be a powerfull tool to study a large class of groups. \; \; \;

\nIn this talk\, based on a common work with Christia n Urech\, we will construct such complexes on which Cremona groups of rank n act. We will then see which kind of results on these groups we can obta in.

DTEND;TZID=Europe/Zurich:20200225T120000 END:VEVENT BEGIN:VEVENT UID:news1027@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200219T095246 DTSTART;VALUE=DATE:20200221 SUMMARY:Workshop P2P Basel DESCRIPTION:Secure Scuttlebutt (SSB) is an application-level secure\, persi sted pub/sub system that has gained popularity in the decentralized Web mo vement. The aim of this workshop is to bring together researchers\, softwa re builders and members of the SSB community to study the properties and p otential of Secure Scuttlebutt. The workshop is open to other decentralize d approaches and networking technolgies e.g. DAT\, Holochain\, IPFS or SOL ID\, as problems and technologies often have considerable similarities. Al so\, a SSB tutorial preceds the workshop\, helping people to get familiar with the Secure Scuttlebutt technology and value system in short time. A t ravel and accommodation grant has been put in place to help facilitate att endance from people without institutional funding. For more information\, see p2p-basel.org [http://p2p-basel.org/].\\r\\nPlease register via christ ian.tschudin@unibas.ch. X-ALT-DESC:Secure Scuttlebutt (SSB) is an application-level secure\, per sisted pub/sub system that has gained popularity in the decentralized Web movement. The aim of this workshop is to bring together researchers\, soft ware builders and members of the SSB community to study the properties and potential of Secure Scuttlebutt. The workshop is open to other decentrali zed approaches and networking technolgies e.g. DAT\, Holochain\, IPFS or S OLID\, as problems and technologies often have considerable similarities. Also\, a SSB tutorial preceds the workshop\, helping people to get familia r with the Secure Scuttlebutt technology and value system in short time. A travel and accommodation grant has been put in place to help facilitate a ttendance from people without institutional funding. For more information\ , see p2p-basel.org.

\nPlea
se register via **christian.tschudin@unibas.ch**.

A formal proof is a proof within an axiomatic system\, where proof steps are either applications of axioms or applications of formally proven statements. Formal proofs have a long history within mathematics\, starting with Euclid's element's which had an axiomatic system for geometr ical reasoning. The main motivation of constructing a formal proof is obta ining unambiguous detailed proofs that can be mechanically checked. The ad vent of computer-based tools for formal proof\, such as automatic and inte ractive theorem provers\, made it feasible to produce formal versions of p roofs that would otherwise be impossible. In this talk I will give an over view of the state-of-the-art as well as my work on the applications of com puter-based formal proofs to computer science and mathematics\, with a spe cial emphasis on their use to construct trustworthy algorithms and softwar e systems.

\n\n\n END:VEVENT BEGIN:VEVENT UID:news997@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200129T121404 DTSTART;TZID=Europe/Zurich:20200213T141500 SUMMARY:Ostrowski Prize 2019 DESCRIPTION:The ceremony in honour of Prof. Dr. Assaf Naor\, recipient of t he Ostrowski Prize 2019\, will take place on February 13\, 2020 at 2:15 p. m. in lecture hall -101 at Alte Universität.\\r\\nWelcoming remarks: \\r\ \nGianluca Crippa\, Head of Department\\r\\n\\r\\nA.M. Ostrowski and the O strowski Prize:\\r\\nHelmut Harbrecht\, President of the Ostrowski Foundat ion\\r\\n\\r\\nLaudation about the work of Assaf Naor: \\r\\nTerence Tao\, University of California\, Los Angeles\\r\\n\\r\\nPresentation of the Med al from the Ostrowski Foundation\\r\\n\\r\\nThe 2019 Ostrowski Prize Lectu re by Assaf Naor\\r\\n\\r\\nAfter the ceremony\, an apéro will be offered . X-ALT-DESC:The ceremony in honour of Prof. Dr. Assaf Naor\, recipient of the Ostrowski Prize 2019\, will take place on February 13\, 2020 at 2:15 p.m. in lecture hall -101 at Alte Universität.

\nWelcoming remarks:

\nGianluca Crippa\, Head of Department

\n\nA.M. Ostrowski an d the Ostrowski Prize:

\nHelmut Harbrecht\, President of the Ostrows ki Foundation

\n\nLaudation about the work of Assaf Naor:

\nT erence Tao\, University of California\, Los Angeles

\n\nPresentation of the Medal from the Ostrowski Foundation

\n\nThe 2019 Ostrowski P rize Lecture by Assaf Naor

\n\nAfter the ceremony\, an apéro will b e offered.

END:VEVENT BEGIN:VEVENT UID:news993@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200113T090323 DTSTART;TZID=Europe/Zurich:20200206T161500 SUMMARY:Actuarial Science: Öffentliche Veranstaltung DESCRIPTION:Donnerstag\, 6. Februar 2020\, ab 16:15\\r\\nAm 6. Februar 193 9 wurde Versicherungslehre an der Universität Basel als selbständiges Examensfach eingeführt. Anlässlich des 80jährigen Bestehens wurde im Februar 2019 AlumniActuarialScience gegründet. \\r\\nIn Zusammenarbeit m it dem Masterstudiengang organisiert AlumniActuarialScience exakt ein Jah r später eine 2. Reunion. Drei Actuarial Science-Studentinnen stellen ih re Abschlussarbeiten vor und Prof.em.Dr. Herbert Lüthy gibt einen kurzen Überblick zur Entwicklung der Versicherungsmathematik. Beim anschliesse nden Apéro bietet sich Gelegenheit\, Studienkolleg*innen und Dozent*inne n wiederzusehen sowie andere Aktuar*innen aus der Region kennenzulernen.\ \r\\nAlle Interessierten sind herzlich eingeladen. \\r\\nAnmeldungFür di e Vorträge und den anschliessenden Apéro in der Alten Universität ist k eine Anmeldung erforderlich. \\r\\nDas AlumniEssen findet im Restaurant Zu m Isaak statt und ist für Mitglieder AlumniActuarialScience und solche\, die es gerne werden wollen. Bitte anmelden bis am 26. Januar 2020 an info@ AlumniActuarialScience.ch [mailto:info@AlumniActuarialScience.ch]. \\r\\nA lumniActuarialScience werdenMitglied werden in der Fachalumni Actuarial Sc ience können ehemalige Studierende Actuarial Science/Versicherungsmathema tik\, Dozierende und Emeriti\, SAV-Hörer*innen und alle am Studiengang in teressierten Privatpersonen und Institutionen. \\r\\nWeitere Informationen : AlumniActuarialScience [t3://page?uid=991]. X-ALT-DESC:Am 6. Februar 1939 wurde Versicherungslehre an der Universität Basel als selbständiges Examensfach eingeführt. Anlässlich des 80jährigen Best ehens wurde im Februar 2019 AlumniActuarialScience gegründet.

\nIn Zusammenarbeit mit dem Masterstudiengang organisiert AlumniActuarialSci ence exakt ein Jahr später eine 2. Reunion. Drei Actuarial Science-Stude ntinnen stellen ihre Abschlussarbeiten vor und Prof.em.Dr. Herbert Lüthy gibt einen kurzen Überblick zur Entwicklung der Versicherungsmathematik . Beim anschliessenden Apéro bietet sich Gelegenheit\, Studienkolleg*inn en und Dozent*innen wiederzusehen sowie andere Aktuar*innen aus der Regio n kennenzulernen.

\nAlle Interessierten sind herzlich eingeladen.&nb sp\;

\n**Anmeldung**

Für die Vorträge und den anschliessen
den Apéro in der Alten Universität ist keine Anmeldung erforderlich.

Das AlumniEssen findet im Restaurant *Zum Isaak* statt und ist
für Mitglieder *AlumniActuarialScience* und solche\, die es gerne we
rden wollen. Bitte anmelden bis am 26. Januar 2020 an info@AlumniActuarialScience.ch.**<
/b>**

*AlumniActuarialScience ***werden**

Mitgl
ied werden in der Fachalumni Actuarial Science können ehemalige Studieren
de Actuarial Science/Versicherungsmathematik\, Dozierende und Emeriti\, SA
V-Hörer*innen und alle am Studiengang interessierten Privatpersonen und I
nstitutionen.

Weitere Informationen: AlumniActuarialScience.< /p> DTEND;TZID=Europe/Zurich:20200206T190000 END:VEVENT BEGIN:VEVENT UID:news999@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200116T145410 DTSTART;TZID=Europe/Zurich:20200117T180000 SUMMARY:DBIS research group at Museumsnacht Basel DESCRIPTION:If you always wanted to take a closer look at the «Basler Mün sterschatz»\, the 20th Museumsnacht Basel [https://museumsnacht.ch/] migh t be the right event for you! On Friday\, January 17th parts of the digiti zed cathedral treasure will be on display in the Virtual Museum of the Dat abase and Information Systems (DBIS) research group [https://dbis.dmi.unib as.ch/] of the University of Basel at Barfüsserkirche. X-ALT-DESC:

If you always wanted to take a closer look at the «Basler M ünsterschatz»\, the 20th Museums nacht Basel might be the right event for you! On Friday\, January 17th parts of the digitized cathedral treasure will be on display in the Virtu al Museum of the Database and I nformation Systems (DBIS) research group of the University of Basel at Barfüsserkirche.

\n\n DTEND;TZID=Europe/Zurich:20200118T020000 END:VEVENT BEGIN:VEVENT UID:news992@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20200107T115203 DTSTART;TZID=Europe/Zurich:20200109T090000 SUMMARY:Bachelor Information Day DESCRIPTION:On Thursday\, January 9\, 2020\, the time has come again: Thous ands of prospective students will come to Basel and visit the "Bachelor In formation Day" [https://dmi.unibas.ch/typo3/On%20Thursday\,%20January%209\ ,%202020\,%20the%20time%20has%20come%20again:%20Thousands%20of%20prospecti ve%20students%20will%20come%20to%20Basel%20and%20visit%20the%20%22Bachelor %20Information%20Day%22%20at%20the%20University%20of%20Basel.%20The%20Depa rtment%20of%20Mathematics%20and%20Computer%20Science%20presents%20itself%2 0from%209:00%20a.m.%20at%20Kollegienhaus%20as%20well%20as%20Bio-%20and%20P harmaceutical%20Center\,%20where%20lecturers%20and%20students%20will%20be% 20happy%20to%20answer%20questions.%20In%20addition\,%20prospective%20stude nts%20have%20the%20opportunity%20to%20visit%20the%20Department%20at%20Spie gelgasse%201%20to%20get%20a%20deeper%20insight.%20The%20visit%20can%20be%2 0designed%20freely%20and%20individually.] (link is only available in Germa n) at the University of Basel. The Department of Mathematics and Computer Science presents itself from 9:00 a.m. at Kollegienhaus as well as Bio- an d Pharmaceutical Center\, where lecturers and students will be happy to an swer questions. In addition\, prospective students have the opportunity to visit the Department at Spiegelgasse 1 to get a deeper insight. The visit can be designed freely and individually. X-ALT-DESC:On Thursday\, January 9\, 2020\, the time has come again: Tho usands of prospective students will come to Basel and visit the "\;Bachelor Information Day"\; (link is only ava ilable in German) at the University of Basel. The Department of Mathematic s and Computer Science presents itself from 9:00 a.m. at Kollegienhaus as well as Bio- and Pharmaceutical Center\, where lecturers and students will be happy to answer questions. In addition\, prospective students have the opportunity to visit the Department at Spiegelgasse 1 to get a deeper ins ight. The visit can be designed freely and individually.

\n\n DTEND;TZID=Europe/Zurich:20200109T170000 END:VEVENT BEGIN:VEVENT UID:news939@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191125T124030 DTSTART;TZID=Europe/Zurich:20191220T110000 SUMMARY:Seminar in Numerical Analysis: Kristin Kirchner (ETH Zürich) DESCRIPTION:Many models in spatial statistics are based on Gaussian Matérn fields. Motivated by the relation between this class of Gaussian random f ields and stochastic partial differential equations (PDEs)\, we consider t he numerical solution of fractional-order elliptic stochastic PDEs with ad ditive spatial white noise on a bounded Euclidean domain.We propose an app roximation supported by a rigorous error analysis which shows different no tions of convergence at explicit and sharp rates. We furthermore discuss t he computational complexity of the proposed method. Finally\, we present s everal numerical experiments\, which attest the theoretical outcomes\, as well as a statistical application where we use the method for inference\, i.e.\, for parameter estimation given data\, and for spatial prediction.\\ r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:Many models in spatial statistics are based on Gaussian Maté
rn fields. Motivated by the relation between this class of Gaussian random
fields and stochastic partial differential equations (PDEs)\, we consider
the numerical solution of fractional-order elliptic stochastic PDEs with
additive spatial white noise on a bounded Euclidean domain.

We
propose an approximation supported by a rigorous error analysis which show
s different notions of convergence at explicit and sharp rates. We further
more discuss the computational complexity of the proposed method. Finally\
, we present several numerical experiments\, which attest the theoretical
outcomes\, as well as a statistical application where we use the method fo
r inference\, i.e.\, for parameter estimation given data\, and for spatial
prediction.

For further information about the seminar\, please vi sit this \;webpage.

DTEND;TZID=Europe/Zurich:20191220T120000 END:VEVENT BEGIN:VEVENT UID:news951@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191217T190150 DTSTART;TZID=Europe/Zurich:20191219T121500 SUMMARY:Bernoullis Tafelrunde: Pascal Oswald DESCRIPTION:Abstract [t3://file?uid=2159] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20191219T130000 END:VEVENT BEGIN:VEVENT UID:news931@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191210T105146 DTSTART;TZID=Europe/Zurich:20191213T110000 SUMMARY:Seminar in Numerical Analysis: Théophile Chaumont-Frelet (INRIA\, Nice/Sophia Antipolis) DESCRIPTION:The Helmholtz equation models the propagation of a time-harmoni c wave. It has received much attention since it is widely employed in appl ications\, but still challenging to numerically simulate in the high-frequ ency regime. In this seminar\, we focus on acoustic waves for the sake of simplicity and consider finite element discretizations. The main goal of the presentation is to highlight the improved performance of high order me thods (as compared to linear finite elements) when the frequency is large. We will very briefly cover the zero-frequency case\, that corresponds to the well-studied Poisson equation. We take advantage of this classical se tting to recall central concepts of the finite element theory such as quas i-optimality and interpolation error. The second part of the seminar is d evoted to the high-frequency case. We show that without restrictive assump tions on the mesh size\, the finite element method is unstable\, and quasi -optimality is lost. We provide a detailed analysis\, as well as numerical examples\, which show that higher order methods are less affected by this phenomena\, and thus more suited to discretize high-frequency problems. Before drawing our main conclusions\, we briefly discuss advanced topics\, such as the use of unfitted meshes in highly heterogeneous media and mesh refinements around re-entrant corners.\\r\\nFor further information about the seminar\, please visit this webpage [t3://page?uid=1115]. X-ALT-DESC:The Helmholtz equation models the propagation of a time-harmo
nic wave.

It has received much attention since it is widely employed
in applications\,

but still challenging to numerically simulate in
the high-frequency regime.

In this seminar\, we focus on acou
stic waves for the sake of simplicity

and consider finite element di
scretizations. The main goal of the

presentation is to highlight the
improved performance of high order

methods (as compared to linear f
inite elements) when the frequency is large.

We will very bri
efly cover the zero-frequency case\, that corresponds to the well-studied
Poisson equation. We take advantage of this classical setting to recall ce
ntral concepts of the finite element theory such as quasi-optimality and i
nterpolation error.

The second part of the seminar is devoted
to the high-frequency case.

We show that without restrictive assump
tions on the mesh size\,

the finite element method is unstable\, and
quasi-optimality is lost.

We provide a detailed analysis\, as well
as numerical examples\, which

show that higher order methods are les
s affected by this phenomena\,

and thus more suited to discretize hi
gh-frequency problems.

Before drawing our main conclusions\,
we briefly discuss advanced topics\,

such as the use of unfitted mes
hes in highly heterogeneous media

and mesh refinements around re-ent
rant corners.

For further information about the seminar\, please v isit this \;webpage.

DTEND;TZID=Europe/Zurich:20191213T120000 END:VEVENT BEGIN:VEVENT UID:news983@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191204T110725 DTSTART;TZID=Europe/Zurich:20191212T161500 SUMMARY:Public inaugural lecture of Prof. Dr. Pierre Le Boudec DESCRIPTION:The Department Mathematics and Computer Science kindly invites you to the inaugural lecture of Prof. Dr. Pierre Le Boudec. After the lec ture an aperitif will be offered. X-ALT-DESC:The Department Mathematics and Computer Science kindly invit es you to the inaugural lecture of Prof. Dr. Pierre Le Boudec. After the l ecture an aperitif will be offered.

\n\n DTEND;TZID=Europe/Zurich:20191212T171500 END:VEVENT BEGIN:VEVENT UID:news950@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191217T185546 DTSTART;TZID=Europe/Zurich:20191212T121500 SUMMARY:Bernoullis Tafelrunde: Ramon Locher DESCRIPTION:Abstract [t3://file?uid=2146] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20191212T130000 END:VEVENT BEGIN:VEVENT UID:news987@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191206T022316 DTSTART;TZID=Europe/Zurich:20191209T150000 SUMMARY:Seminar Algebra and Geometry: Michel van Garrel (Warwick) DESCRIPTION:In this joint work with Christian Böhning and Hans-Christian von Bothmer we apply Voisin's criterion of existence of a decomposition o f the diagonal to semistable degenerations. In doing so\, we obtain partia l results towards proving that very general cubic threefolds are stably ir rational. X-ALT-DESC:In this joint work with Christian \;Böhning \;and Hans- Christian von Bothmer we apply Voisin's criterion of existence of a decomp osition of the diagonal to semistable degenerations. In doing so\, we obta in partial results towards proving that very general cubic threefolds are stably irrational. DTEND;TZID=Europe/Zurich:20191209T163000 END:VEVENT BEGIN:VEVENT UID:news926@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191130T081127 DTSTART;TZID=Europe/Zurich:20191206T110000 SUMMARY:Seminar in Numerical Analysis: Ira Neitzel (Universität Bonn) DESCRIPTION:joint work with Dominik Hafemeyer\, Florian Mannel and Boris Ve xler\\r\\n We consider a convex optimal control problem governed by a par tial differential equation in one space dimension which is controlled by a right-hand-side living in the space of functions with bounded variation . These functions tend to favor optimal controls that are piecewise const ant with often finitely many jump poins. We are interested in deriving fi nite element discretization error estimates for the controls when the sta te ist discretized with usual piecewise linear finite elements\, and the c ontrols is either variationally discrete or piecwise constant. Due to the structure of the objective function\, usual techniques for estimating th e control error cannot be applied. Instead\, these have to be derived fro m (suboptimal) error estimates for the state\, which can later be improved . \\r\\nFor further information about the seminar\, please visit this web page [t3://page?uid=current]. X-ALT-DESC:joint work with Dominik Hafemeyer\, Florian Mannel and Boris Vexler

\n

We consider a convex optimal control problem govern
ed by a partial differential equation in one space dimension which is con
trolled by a right-hand-side living in the space of functions with bounde
d variation. These functions tend to favor optimal controls that are piece
wise constant with often finitely many jump poins. We are interested in
deriving finite element discretization error estimates for the controls w
hen the state ist discretized with usual piecewise linear finite elements\
, and the controls is either variationally discrete or piecwise constant.
Due to the structure of the objective function\, usual techniques for es
timating the control error cannot be applied. Instead\, these have to be
derived from (suboptimal) error estimates for the state\, which can later
be improved.

For further information about the seminar\, please v isit this \;webpage.

DTEND;TZID=Europe/Zurich:20191206T120000 END:VEVENT BEGIN:VEVENT UID:news949@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191127T105351 DTSTART;TZID=Europe/Zurich:20191205T121500 SUMMARY:Bernoullis Tafelrunde: Erik Paemurru DESCRIPTION:Abstract [t3://file?uid=2114] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20191205T130000 END:VEVENT BEGIN:VEVENT UID:news922@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191127T114131 DTSTART;TZID=Europe/Zurich:20191203T103000 SUMMARY:Seminar Algebra and Geometry: Erik Paemurru (University of Loughbor ough) DESCRIPTION:It is known that quasismooth 3-fold Fano hypersurfaces with ind ex 1 in weighted projective spaces over ℂ are birationally rigid (not bi rational to any other Fano 3-folds\, conic bundles or del Pezzo fibrations ). But very little is known when they carry non-orbifold singularities. I consider sextic double solids\, one of the simplest such 3-folds\, which h ave an isolated cA_n singularity. I have shown that n is at most 8\, and t hat rigidity fails for n > 3. In this talk\, I will illustrate this phenom enon by giving some examples. X-ALT-DESC:It is known that quasismooth 3-fold Fano hypersurfaces with inde x 1 in weighted projective spaces over ℂ are birationally rigid (not bir ational to any other Fano 3-folds\, conic bundles or del Pezzo fibrations) . But very little is known when they carry non-orbifold singularities. I c onsider sextic double solids\, one of the simplest such 3-folds\, which ha ve an isolated cA_n singularity. I have shown that n is at most 8\, and th at rigidity fails for n >\; 3. In this talk\, I will illustrate this phe nomenon by giving some examples. DTEND;TZID=Europe/Zurich:20191203T120000 END:VEVENT BEGIN:VEVENT UID:news948@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191122T134744 DTSTART;TZID=Europe/Zurich:20191128T121500 SUMMARY:Bernoullis Tafelrunde: Pascale Vögtli DESCRIPTION:abstract [t3://file?uid=2100] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20191128T130000 END:VEVENT BEGIN:VEVENT UID:news924@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191112T123824 DTSTART;TZID=Europe/Zurich:20191126T103000 SUMMARY:Seminar Algebra and Geometry: Carlos Amendola (University of Munich ) DESCRIPTION:We study the maximum likelihood estimation problem for several classes of toric Fano models. We start by exploring the maximum likelihood degree for all 2-dimensional Gorenstein toric Fano varieties. We show tha t the ML degree is equal to the degree of the surface in every case except for the quintic del Pezzo surface with two singular points of type A1 and provide explicit expressions that allow to compute the maximum likelihood estimate in closed form whenever the ML degree is less than 5. We then ex plore the reasons for the ML degree drop using A-discriminants and interse ction theory. Based on joint work with Dimitra Kosta and Kaie Kubjas. X-ALT-DESC:We study the maximum likelihood estimation problem for several c lasses of toric Fano models. We start by exploring the maximum likelihood degree for all 2-dimensional Gorenstein toric Fano varieties. We show that the ML degree is equal to the degree of the surface in every case except for the quintic del Pezzo surface with two singular points of type A1 and provide explicit expressions that allow to compute the maximum likelihood estimate in closed form whenever the ML degree is less than 5. We then exp lore the reasons for the ML degree drop using A-discriminants and intersec tion theory. Based \;on joint work with Dimitra Kosta and Kaie Kubjas. DTEND;TZID=Europe/Zurich:20191126T120000 END:VEVENT BEGIN:VEVENT UID:news918@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191030T110831 DTSTART;TZID=Europe/Zurich:20191125T161500 SUMMARY:PhD Defense Mathematics: Gabriel Dill DESCRIPTION:Unlikely Intersections with Isogeny Orbits X-ALT-DESC:Unlikely Intersections with Isogeny Orbits END:VEVENT BEGIN:VEVENT UID:news848@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191105T121925 DTSTART;TZID=Europe/Zurich:20191122T151500 SUMMARY:Perlen-Kolloquium: PD Dr. Andreas Verdun (University of Berne) DESCRIPTION:The talk is organized as a joint event with the Department of P hysics within the Physics-Colloquium. After the talk the vernissage of the volume II/26 of Opera Omnia of Leonhard Euler will take place\, followed by an apero. \\r\\nFurther details can be found on the website of the De partment of Physics [https://www.physik.unibas.ch/aktuell/seminars-colloqu ia/events-details/events/486-joint-colloquium-of-the-department-of-physics -and-the-department-of-mathematics-and-computer-sc.html]. X-ALT-DESC:The talk is organized as a joint event with the Department of Physics within the Physics-Colloquium. After the talk the vernissage of t he volume II/26 of Opera Omnia of Leonhard Euler will take place\, followe d by an apero. \;

\nFurther details can be found on the website of the Department of Physics.

END:VEVENT BEGIN:VEVENT UID:news916@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191107T090541 DTSTART;TZID=Europe/Zurich:20191121T161500 SUMMARY:PhD Defense Mathematics: Silvia Ligabue DESCRIPTION:The talk is open to members of the university. X-ALT-DESC:The talk is open to members of the university.

END:VEVENT BEGIN:VEVENT UID:news965@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191110T111301 DTSTART;TZID=Europe/Zurich:20191115T171500 SUMMARY:BZ Seminar in Analysis: Paolo Antonelli (GSSI L'Aquila) DESCRIPTION:The quantum hydrodynamics (QHD) system is a model used to descr ibe macroscopic objects exhibiting quantum features\, as for instance in s uperfluidity\, Bose-Einstein condensation or semiconductor devices. They a re characterized by a compressible\, inviscid flow subject to a stress ten sor depending on the particle density and its derivatives\, that adds disp ersive effects in the system. The Cauchy theory for finite energy weak sol utions exploits the analogy between the QHD system and nonlinear Schrödin ger (NLS) dynamics\, through the Madelung transform. By using a polar fact orization approach it is possible to make this analogy rigorous in the spa ce of finite energy weak solutions. Furthermore the hydrodynamic formulati on allows to include some dissipative effects which cannot be treated with the NLS dynamics. The polar decomposition can also be exploited to study the problem with non-trivial conditions at infinity. This analysis is moti vated by future applications to quantized vortex dynamics. The main drawba ck of this approach is that the initial data for the hydrodynamical system need to be consistent with a wave function by means of the Madelung trans form\; at present it is not clear what is the degree of generality of such initial data. We show that in the one-dimensional case we can eliminate t his assumption and we prove global existence of finite energy weak solutio ns to the QHD system with general initial data. Moreover\, by introducing a novel functional we are also able to determine a class of solutions for which we can prove stability\, namely given a sequence of solutions satisf ying some uniform bounds there is a subsequence converging to a weak solut ion to the QHD system. This talk is based on a series of works done in col laboration with P. Marcati and our PhD students L. E. Hientzsch and H. Zhe ng. X-ALT-DESC:The quantum hydrodynamics (QHD) system is a model used to des cribe macroscopic objects exhibiting quantum features\, as for instance in superfluidity\, Bose-Einstein condensation or semiconductor devices. They are characterized by a compressible\, inviscid flow subject to a stress t ensor depending on the particle density and its derivatives\, that adds di spersive effects in the system. The Cauchy theory for finite energy weak s olutions exploits the analogy between the QHD system and nonlinear Schröd inger (NLS) dynamics\, through the Madelung transform. By using a polar fa ctorization approach it is possible to make this analogy rigorous in the s pace of finite energy weak solutions. Furthermore the hydrodynamic formula tion allows to include some dissipative effects which cannot be treated wi th the NLS dynamics. The polar decomposition can also be exploited to stud y the problem with non-trivial conditions at infinity. This analysis is mo tivated by future applications to quantized vortex dynamics. The main draw back of this approach is that the initial data for the hydrodynamical syst em need to be consistent with a wave function by means of the Madelung tra nsform\; at present it is not clear what is the degree of generality of su ch initial data. We show that in the one-dimensional case we can eliminate this assumption and we prove global existence of finite energy weak solut ions to the QHD system with general initial data. Moreover\, by introducin g a novel functional we are also able to determine a class of solutions fo r which we can prove stability\, namely given a sequence of solutions sati sfying some uniform bounds there is a subsequence converging to a weak sol ution to the QHD system. This talk is based on a series of works done in c ollaboration with P. Marcati and our PhD students L. E. Hientzsch and H. Z heng.

DTEND;TZID=Europe/Zurich:20191115T180000 END:VEVENT BEGIN:VEVENT UID:news964@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191106T190030 DTSTART;TZID=Europe/Zurich:20191115T161500 SUMMARY:BZ Seminar in Analysis: Juan J. L. Velázquez (University of Bonn) DESCRIPTION:It is well known that in kinetic models satisfying the so-calle d detailed balance condition\, it is possible to construct an entropy func tional which can be used to derive convergence to equilibrium results. On the other hand\, there are many physical situations (typically open system s) where it is natural to use kinetic equations for which the detailed bal ance condition fails. In these cases more complicated dynamical behaviours can arise\, for instance oscillatory behaviours. A class of kinetic equat ions where it is not a priori obvious if temporal oscillations can take pl ace are the coagulation-fragmentation equations. These equations have been extensively used to model chemical systems. In this talk I will describe two examples of coagulation-fragmentation models for which the onset of pe riodic oscillations can be rigorously proved. One of the models describes the formation of large clusters in a kinetic equation having a source of m onomers. The second model is a closed coagulation-fragmentation model with out external monomer sources\, but in which the detailed balance condition fails at one of the reactions. X-ALT-DESC:It is well known that in kinetic models satisfying the so-called detailed balance condition\, it is possible to construct an entropy funct ional which can be used to derive convergence to equilibrium results. On t he other hand\, there are many physical situations (typically open systems ) where it is natural to use kinetic equations for which the detailed bala nce condition fails. In these cases more complicated dynamical behaviours can arise\, for instance oscillatory behaviours. A class of kinetic equati ons where it is not a priori obvious if temporal oscillations can take pla ce are the coagulation-fragmentation equations. These equations have been extensively used to model chemical systems. In this talk I will describe t wo examples of coagulation-fragmentation models for which the onset of per iodic oscillations can be rigorously proved. One of the models describes t he formation of large clusters in a kinetic equation having a source of mo nomers. The second model is a closed coagulation-fragmentation model witho ut external monomer sources\, but in which the detailed balance condition fails at one of the reactions. DTEND;TZID=Europe/Zurich:20191115T170000 END:VEVENT BEGIN:VEVENT UID:news930@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191107T104152 DTSTART;TZID=Europe/Zurich:20191115T110000 SUMMARY:Seminar in Numerical Analysis: Michael Multerer (USI Lugano) DESCRIPTION:The numerical simulation of physical phenomena is very well und erstood given that the input data are given exactly. However\, in practic e\, the collection of these data is usually subjected to measurement erro rs. The goal of uncertainty quantification is to assess those errors and their possible impact on simulation results.In this talk\, we address diff erent numerical aspects of uncertainty quantification in elliptic partial differential equations on random domains. Starting from the modelling of random domains via random vector fields\, wediscuss how the corresponding Karhunen-Loève expansion can efficiently becomputed. For the discretisat ion of the partial differential equation\, we apply an adaptive Galerkin framework. An a posteriori error estimator is presented\, which allows fo r the problem-dependent iterative refinement of all discretisation paramet ers and the assessment of the achieved error reduction. The proposed appr oach is demonstrated in numerical benchmark problems.\\r\\nFor further in formation about the seminar\, please visit this webpage [t3://page?uid=11 15]. X-ALT-DESC:The numerical simulation of physical phenomena is very well u nderstood given that \;the input data are given exactly. However\, in practice\, the collection of these \;data is usually subjected to meas urement errors. The goal of uncertainty quantification \;is to assess those errors and their possible impact on simulation results.In this talk\ , we address different numerical aspects of uncertainty quantification&nbs p\;in elliptic partial differential equations on random domains. \;Sta rting from the modelling of random domains via random vector fields\, wedi scuss how the corresponding Karhunen-Loève expansion can efficiently beco mputed. For the discretisation of the partial differential equation\, \;we apply an adaptive Galerkin framework. An a posteriori error estimator is presented\, \;which allows for the problem-dependent iterative ref inement of all discretisation parameters \;and the assessment of the a chieved error reduction. The proposed approach is demonstrated \;in nu merical benchmark problems.

\nFor further information about the semi nar\, please visit this \;webpage.

DTEND;TZID=Europe/Zurich:20191115T120000 END:VEVENT BEGIN:VEVENT UID:news910@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191203T141548 DTSTART;TZID=Europe/Zurich:20191114T161500 SUMMARY:Perlen-Kolloquium: Prof. Dr. Jürgen Hausen (Universität Tübingen ) DESCRIPTION:We begin with a short introduction to the theory of toric varie ties\, that means\, equivariant embeddings of the algebraic torus (k✲)n . Then we indicate how the methods of toric geometry can be extended to more general torus actions. As an application\, we discuss recent classif ication results for Fano varieties.\\r\\nFlyer [t3://file?uid=2017] X-ALT-DESC:We begin with a short introduction to the theory of toric var
ieties\, that means\, equivariant embeddings of the algebraic torus (k✲
)^{n}. Then we indicate how the methods of toric geometry can be
extended to more general torus actions. As an application\, we discuss re
cent classification results for Fano varieties.

DTEND;TZID=Europe/Zurich:20191112T120000 END:VEVENT BEGIN:VEVENT UID:news920@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191104T081039 DTSTART;TZID=Europe/Zurich:20191108T110000 SUMMARY:Seminar in Numerical Analysis: Omar Lakkis (University of Sussex) DESCRIPTION:Aposteriori error estimates provide a rigorous foundation for t he derivation of efficient adaptive algorithms for the approximation of so lutions of partial differential equations (PDEs). While the literature i s rich with results for the approximation of elliptic and parabolic PDEs\, it is much less developed for the hyperbolic equations such as the acoust ic or elastic wave equations. In this talk\, I will review some of the " standard" aposteriori results for the scalar linear wave equation\, includ ing those of [1] and [2]\, and present recent improvements and further dev elopments to lower order Sobolev norms based on Baker’s Trick [3] for ba ckward Euler schemes. Subsequent focus will be given to practically rele vant methods such as Verlet\, Cosine\, or Newmark methods\, a popular exam ple of which is the Leap-frog method [4].\\r\\nNotes: This is based on joi nt work with E.H. Georgoulis\, C. Makridakis and J.M. Virtanen.\\r\\nRefer ences:\\r\\n[1] W. Bangerth and R. Rannacher\, J. Comput. Acoust. 9(2):575 –591\, 2001.[2] C. Bernardi and E. Süli\, Math. Models Methods Appl. Sc i. 15(2):199--225\, 2005.[3] E. H. Georgoulis\, O. Lakkis\, and C. Makrida kis. IMA J. Numer. Anal.\, 33(4):1245–1264\, 2013\, http://arxiv.org/abs /1003.3641[4] E. H. Georgoulis\, O. Lakkis\, C. Makridakis\, and J. M. Vir tanen. SIAM J. Numer. Anal.\, 54(1)\, 2016\, http://arxiv.org/abs/1411.757 2 \\r\\nFor further information about the seminar\, please visit this web page [t3://page?uid=1115]. X-ALT-DESC:

Aposteriori error estimates provide a rigorous foundation for the derivation of efficient adaptive algorithms for the approximation of solutions of partial differential equations (PDEs). \;While the liter ature is rich with results for the approximation of elliptic and parabolic PDEs\, it is much less developed for the hyperbolic equations such as the acoustic or elastic wave equations. \;In this talk\, I will review s ome of the "\;standard"\; aposteriori results for the scalar linea r wave equation\, including those of [1] and [2]\, and present recent impr ovements and further developments to lower order Sobolev norms based on Ba ker’s Trick [3] for backward Euler schemes. \;Subsequent focus will be given to practically relevant methods such as Verlet\, Cosine\, or New mark methods\, a popular example of which is the Leap-frog method [4].

\n

Notes: This is based on joint work with E.H. Georgoulis\, C. Ma
kridakis and J.M. Virtanen.

References:

\n[1] W. Bange
rth and R. Rannacher\, J. Comput. Acoust. 9(2):575–591\, 2001.

[2]
C. Bernardi and E. Süli\, Math. Models Methods Appl. Sci. 15(2):199--225\
, 2005.

[3] E. H. Georgoulis\, O. Lakkis\, and C. Makridakis. IMA J.
Numer. Anal.\, 33(4):1245–1264\, 2013\, http://arxiv.org/abs/1003.3641**[4] E. H. Georgoulis\, O. Lakkis\, C. Makridakis\, and J. M. Virtanen.
SIAM J. Numer. Anal.\, 54(1)\, 2016\, http://arxiv.org/abs/1411.7572 **

For further information about the seminar\, please visit this \;< a href="t3://page?uid=1115" title="Opens internal link in current window" class="internal-link">webpage.

DTEND;TZID=Europe/Zurich:20191108T120000 END:VEVENT BEGIN:VEVENT UID:news947@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191022T224439 DTSTART;TZID=Europe/Zurich:20191106T111500 SUMMARY:Bernoullis Tafelrunde: ShengYuan Zhao DESCRIPTION:Abstract [t3://file?uid=2000] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20191106T120000 END:VEVENT BEGIN:VEVENT UID:news925@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191020T194626 DTSTART;TZID=Europe/Zurich:20191105T103000 SUMMARY:Seminar Algebra and Geometry: Shengyuan Zhao (University of Rennes) DESCRIPTION:Let Y be a smooth complex projective surface. Let U be a connec ted Euclidean open set of Y. Let G be a subgroup of Bir(Y) which acts by h olomorphic diffeomorphisms on U (i.e. preserves U and without indeterminac y points in U)\, in a free\, properly discontinuous and cocompact way\, so that the quotient X=U/G is a compact complex surface. Such a birational t ransformation group G\, or more precisely such a quadruple (Y\,U\,G\,X)\, will be called a birational Kleinian group. Once we have a birational Klei nian group\, the quotient surface is equipped with a birational structure\ , i.e. an atlas of local charts with rational changes of coordinates. I wi ll present some basic properties and subtleties of birational structures\, compared to the classical geometric structures. Then I will begin by stud ying birational structures on a special type of non-algebraic surfaces\, t he Inoue surfaces\, to reveal some of the general strategy. Using classifi cation of solvable and abelian groups of the Cremona group\, and by relati ng the foliations on Inoue surfaces with some birational dynamical systems via Ahlfors-Nevanlinna currents\, I will show that the Inoue surfaces hav e one unique birational structure. Then I will move on to the general stud y of birational Kleinian groups with the additional hypothesis that the qu otient surface is projective. I will explain how to use powerful results f rom Cremona groups\, holomorphic foliations and non-abelian Hodge theory t o get an almost complete classification of such birational Kleinian groups . X-ALT-DESC:Traditional explicit Runge--Kutta schemes\, though computatio
nally inexpensive\, are inefficient for the integration of stiff ordinary
differential equations due to stability issues. Conversely\, implicit sche
mes are stable but can be overly expensive due to the solution of possibly
large nonlinear systems with Newton-like methods\, whose convergence is n
either guaranteed for large time steps. Explicit stabilized schemes such a
s the Runge--Kutta--Chebyshev method (RKC) \; represent a viable compr
omise\, as the width of their stability domain grows quadratically with re
spect to the number of function evaluations\, thus presenting enhanced sta
bility properties with a reasonable computational cost. These methods are
particularly efficient for systems arising from the space discretization o
f parabolic partial differential equations (PDEs).

The efficiency of
these methods deteriorates as the system becomes stiffer\, even if stiffne
ss is induced by only few degrees of freedom. In the framework of discreti
zed parabolic PDEs\, the number of function evaluations has to be chosen i
nversely proportional to the smallest element size in order to achieve sta
bility\, thus largely wasting computational resources on locally-refined m
eshes. We first tackle this issue by replacing the right hand side of the
PDE with an averaged force\, which is obtained by damping the high modes d
own using the dissipative effect of the equation itself and which is cheap
to evaluate. Combining RKC methods with the averaged force we give rise t
o multirate RKC schemes\, for which the number of expensive function evalu
ations is independent of the small elements' size.

The stability prop
erties of our method are demonstrated on a model problem and numerical exp
eriments confirm that the stability bottleneck caused by a few of fine mes
h elements can be overcome without sacrificing accuracy.

For furth er information about the seminar\, please visit this \;webpage.

DTEND;TZID=Europe/Zurich:20191101T120000 END:VEVENT BEGIN:VEVENT UID:news946@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191022T224411 DTSTART;TZID=Europe/Zurich:20191031T121500 SUMMARY:Bernoullis Tafelrunde: Gabriel Dill DESCRIPTION:Abstract [t3://file?uid=1999] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20191031T130000 END:VEVENT BEGIN:VEVENT UID:news944@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191021T121301 DTSTART;TZID=Europe/Zurich:20191029T181500 SUMMARY:Was machst du mit deinem Matheabschluss? DESCRIPTION:The speech is held in English and is interesting also for stude nts of actuarial science.\\r\\nLink to the Flyer [t3://file?uid=1980]\\r\\ n\\r\\nNext event:\\r\\nNovember 12\, 2019\\r\\nOrhan Yildirim\, Data Scie ntist at IWB (Deutsch) X-ALT-DESC:The speech is held in English and is interesting also for stu dents of actuarial science.

\n\n\n**Next event:**

November 12\, 2019

\nOrhan Yi ldirim\, Data Scientist at IWB (Deutsch)

\n\n DTEND;TZID=Europe/Zurich:20191029T190000 END:VEVENT BEGIN:VEVENT UID:news923@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191004T195327 DTSTART;TZID=Europe/Zurich:20191029T103000 SUMMARY:Seminar Algebra and Geometry: Stavros Papadakis (University of Ioan nina) DESCRIPTION:Un projection theory\, initiated by Miles Reid\, aims to constr uct and analyze complicated commutative rings in terms of simpler ones. It can also be considered as an algebraic language for birational geometry. \\r\\nThe main purpose of the talk is to give a short introduction to the theory and describe some of its applications. X-ALT-DESC:Un projection theory\, initiated by Miles Reid\, aims to constru ct and analyze complicated commutative rings in terms of simpler ones. It can also be considered as an algebraic language for birational geometry. \ nThe main purpose of the talk is to give a short introduction to the theor y and describe some of its applications. DTEND;TZID=Europe/Zurich:20191029T120000 END:VEVENT BEGIN:VEVENT UID:news945@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191022T224336 DTSTART;TZID=Europe/Zurich:20191024T121500 SUMMARY:Bernoullis Tafelrunde: Gerold Schefer DESCRIPTION:Abstract [t3://file?uid=1991] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20191024T130000 END:VEVENT BEGIN:VEVENT UID:news929@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191015T153025 DTSTART;TZID=Europe/Zurich:20191023T141500 SUMMARY:Seminar Analysis and Mathematical Physics: Fabian Ziltener (Utrecht University) DESCRIPTION:The goal of this talk is to show in an example how analysis and symplectic geometry are related in several ways.Symplectic geometry origi nated from classical mechanics\, where the canonical symplectic form on ph ase space appears in Hamilton's equation. A (smooth) diffeomorphism on a s ymplectic manifold is called a symplectomorphism iff it preserves the symp lectic form. This happens iff the diffeomorphism solves a certain inhomoge neous quadratic first order system of PDE's. In classical mechanics symple ctomorphisms play the role of canonical transformations.A famous result by Eliashberg and Gromov states that the set of symplectomorphisms is $C^0$- closed in the set of all diffeomorphisms. This is remarkable\, since in ge neral\, the $C^0$-limit of a sequence of solutions of a first order system of PDE's need not solve the system. A well-known proof of the Eliashberg- Gromov theorem is based on Gromov's symplectic nonsqueezing theorem for ba lls.In my talk I will sketch this proof. Furthermore\, I will present a sy mplectic nonsqueezing result for spheres that sharpens Gromov's theorem. T he proof of this result is based on the existence of a holomorphic map fro m the (real) two-dimensional unit disk to a certain symplectic manifold\, satisfying some Lagrangian boundary condition. Such a map solves the Cauch y-Riemann equation for a certain almost complex structure. X-ALT-DESC:The goal of this talk is to show in an example how analysis and symplectic geometry are related in several ways.Symplectic geo metry originated from classical mechanics\, where the canonical symplectic form on phase space appears in Hamilton's equation. A (smooth) diffeomorp hism on a symplectic manifold is called a symplectomorphism iff it preserv es the symplectic form. This happens iff the diffeomorphism solves a certa in inhomogeneous quadratic first order system of PDE's. In classical mecha nics symplectomorphisms play the role of canonical transformations.

< br />A famous result by Eliashberg and Gromov states that the set of sympl ectomorphisms is $C^0$-closed in the set of all diffeomorphisms. This is r emarkable\, since in general\, the $C^0$-limit of a sequence of solutions of a first order system of PDE's need not solve the system. A well-known p roof of the Eliashberg-Gromov theorem is based on Gromov's symplectic nons queezing theorem for balls.

In my talk I will sketch this proof . Furthermore\, I will present a symplectic nonsqueezing result for sphere s that sharpens Gromov's theorem. The proof of this result is based on the existence of a holomorphic map from the (real) two-dimensional unit disk to a certain symplectic manifold\, satisfying some Lagrangian boundary con dition. Such a map solves the Cauchy-Riemann equation for a certain almost complex structure. DTEND;TZID=Europe/Zurich:20191023T160000 END:VEVENT BEGIN:VEVENT UID:news943@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191021T120830 DTSTART;TZID=Europe/Zurich:20191022T181500 SUMMARY:Was machst du mit deinem Matheabschluss? DESCRIPTION:The speech is held in English and is interesting also for stude nts of actuarial science.\\r\\nLink to the Flyer [t3://file?uid=1980]\\r\\ n\\r\\nNext events:\\r\\nOctober 29\, 2019\\r\\nChristian Graf\, Non-life pricing for commercial lines at Allianz Suisse (English)\\r\\n-------\\r\\ nNovember 12\, 2019\\r\\nOrhan Yildirim\, Data Scientist at IWB (Deutsch) X-ALT-DESC:

The speech is held in English and is interesting also for stu dents of actuarial science.

\n\n\n**Next events:**

October 29\, 2019

\nChristia n Graf\, Non-life pricing for commercial lines at Allianz Suisse (English)

\n-------

\nNovember 12\, 2019

\nOrhan Yildirim\, Data Scientist at IWB (Deutsch)

\n\n DTEND;TZID=Europe/Zurich:20191022T190000 END:VEVENT BEGIN:VEVENT UID:news914@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190903T092822 DTSTART;TZID=Europe/Zurich:20191017T161500 SUMMARY:PhD Defense Mathematics: Jet Hoe Tang DESCRIPTION:The talk is open to members of the university. X-ALT-DESC:The talk is open to members of the university. END:VEVENT BEGIN:VEVENT UID:news940@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191022T224307 DTSTART;TZID=Europe/Zurich:20191017T121500 SUMMARY:Bernoullis Tafelrunde: Christiane Scherb DESCRIPTION:Abstract [t3://file?uid=1964] X-ALT-DESC: DTEND;TZID=Europe/Zurich:20191017T130000 END:VEVENT BEGIN:VEVENT UID:news934@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191004T195339 DTSTART;TZID=Europe/Zurich:20191015T103000 SUMMARY:Seminar Algebra and Geometry: Tomasz Pełka (University of Bern) DESCRIPTION:ℚ-homology planes satisfying the Negativity Conjecture X-ALT-DESC:ℚ-homology planes satisfying the Negativity Conjecture DTEND;TZID=Europe/Zurich:20191015T120000 END:VEVENT BEGIN:VEVENT UID:news936@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191007T112822 DTSTART;TZID=Europe/Zurich:20191010T121500 SUMMARY:Bernoullis Tafelrunde: Anna Bot DESCRIPTION:Abstract [t3://file?uid=1931] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20191010T130000 END:VEVENT BEGIN:VEVENT UID:news933@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20191004T195349 DTSTART;TZID=Europe/Zurich:20191008T103000 SUMMARY:Seminar Algebra and Geometry: Christian Urech (EPFL) DESCRIPTION:Julie Déserti showed that every automorphism of the plane Crem ona group is inner up to a field automorphism of the base-field. In this t alk we generalize this result to Cremona groups of arbitrary rank\, howeve r\, only under the additional restriction that the automorphisms are also homeomorphisms with respect to the Zariski or the Euclidean topology on th e Cremona group. We will consider similar questions for groups of polynomi al automorphisms and groups of birational diffeomorphisms. This is joint w ork with Susanna Zimmermann. X-ALT-DESC: Julie Déserti showed that every automorphism of the plane Crem ona group is inner up to a field automorphism of the base-field. In this t alk we generalize this result to Cremona groups of arbitrary rank\, howeve r\, only under the additional restriction that the automorphisms are also homeomorphisms with respect to the Zariski or the Euclidean topology on th e Cremona group. We will consider similar questions for groups of polynomi al automorphisms and groups of birational diffeomorphisms. This is joint w ork with Susanna Zimmermann. DTEND;TZID=Europe/Zurich:20191008T120000 END:VEVENT BEGIN:VEVENT UID:news928@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092719 DTSTART;TZID=Europe/Zurich:20191003T121500 SUMMARY:Bernoullis Tafelrunde: Philipp Mekler DESCRIPTION:Abstract [t3://file?uid=1894] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20191003T130000 END:VEVENT BEGIN:VEVENT UID:news903@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190910T145802 DTSTART;TZID=Europe/Zurich:20190918T100000 SUMMARY:PhD Defense Mathematics: Christine Bürli DESCRIPTION:The talk is open to members of the university. X-ALT-DESC:The talk is open to members of the university. END:VEVENT BEGIN:VEVENT UID:news897@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190618T172419 DTSTART;TZID=Europe/Zurich:20190912T163000 SUMMARY:Horizon 2020 - Information and Networking in "Information and Commu nication Technologies\, ICT" DESCRIPTION:The aim of this event is to provide an overview about research funding opportunities from the European programme Horizon 2020 in the fi eld of “Information and Communication Technologies (ICT)”. Representa tives from academia and industry will meet and get informed on how Europe an funding can support them in the implementation of projects in ICT. \\r \\nIn addition\, information is provided how to identify topics of interes t and find partners to submit proposals from basic research to market appl ication. \\r\\nHorizon 2020 project winners from academia and industry wil l give insights into running projects. \\r\\nFor the 2020 Work Programme\ , the areas of Artificial Intelligence (AI)\, digitizing European Industr y\, HPC\, Big Data\, Cloud technologies\, 5G\, Next Generation Internet ( NGI) and key technologies for digital transformation from photonics to so ftware\, advanced and smart connectivity are prioritized. \\r\\n\\r\\nPle ase register online [https://www.euresearch.ch/en/events/event-detail/show Uid/927/]. X-ALT-DESC:The aim of this event is to provide an overview about research funding opportunities from the European programme Horizon 2020 in the fie ld of “Information and Communication Technologies (ICT)”. Representat ives from academia and industry will meet and get informed on how Europea n funding can support them in the implementation of projects in ICT. \nIn addition\, information is provided how to identify topics of interest and find partners to submit proposals from basic research to market applicati on. \nHorizon 2020 project winners from academia and industry will give in sights into running projects. \nFor the 2020 Work Programme\, the areas o f Artificial Intelligence (AI)\, digitizing European Industry\, HPC\, Big Data\, Cloud technologies\, 5G\, Next Generation Internet (NGI) and key technologies for digital transformation from photonics to software\, adva nced and smart connectivity are prioritized. \n\nPlease register onlin e. DTEND;TZID=Europe/Zurich:20190912T190000 END:VEVENT BEGIN:VEVENT UID:news907@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190814T084956 DTSTART;TZID=Europe/Zurich:20190904T083000 SUMMARY:PhD Summer School: "Ethical\, Legal\, and Societal Implications of Big Data and Data Analytics" DESCRIPTION:Education and training in Data Analytics and Big Data usually f ocuses on technical aspects\, especially w. r. t. the underlying methods f or linking existing data collections and for analyzing such integrated col lections. While these methods are essential in concrete applications\, als o awareness on non-technical aspects like the implications of Data Analyti cs on society\, legal aspects\, and ethical aspect are equally important. This summer school aims at providing an introduction to these three areas for members of the PhD program Data Analytics by experts from the humaniti es\, ethics\, and law.\\r\\nMore information on the summer school and a li nk for the enrollment can be found here [t3://page?uid=1805]. X-ALT-DESC:Education and training in Data Analytics and Big Data usually fo cuses on technical aspects\, especially w. r. t. the underlying methods fo r linking existing data collections and for analyzing such integrated coll ections. While these methods are essential in concrete applications\, also awareness on non-technical aspects like the implications of Data Analytic s on society\, legal aspects\, and ethical aspect are equally important. T his summer school aims at providing an introduction to these three areas f or members of the PhD program Data Analytics by experts from the humanitie s\, ethics\, and law.\nMore information on the summer school and a link fo r the enrollment can be found here. DTEND;TZID=Europe/Zurich:20190906T160000 END:VEVENT BEGIN:VEVENT UID:news864@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190430T141355 DTSTART;VALUE=DATE:20190708 SUMMARY:Conference in Analysis: GMT and PDEs in Basel DESCRIPTION:https://erc-flirt.dmi.unibas.ch/en/gmt-pde-2019/ [https://erc-f lirt.dmi.unibas.ch/en/gmt-pde-2019/] X-ALT-DESC:\nhttps://erc-flirt.dmi.unibas.ch/en/gmt-pde-2019/ DTEND;VALUE=DATE:20190710 END:VEVENT BEGIN:VEVENT UID:news898@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190619T152715 DTSTART;TZID=Europe/Zurich:20190703T103000 SUMMARY:Seminar Algebra and Geometry: Stéphane Lamy (Université de Toulou se) DESCRIPTION:The group of tame polynomial automorphisms of the n-dimensional complex affine space is the group generated by linear maps and polynomial transvections. I will describe an action of this group on a metric space whose construction is inspired from the theory of affine Bruhat-Tits build ings. In dimension n = 3\, we show that this space is simply connected wit h non-positive curvature. This allows to get a description of the finite s ubgroups of the 3-dimensional tame group. (Joint work with P. Przytycki) X-ALT-DESC:The group of tame polynomial automorphisms of the n-dimensional complex affine space is the group generated by linear maps and polynomial transvections. I will describe an action of this group on a metric space w hose construction is inspired from the theory of affine Bruhat-Tits buildi ngs. In dimension n = 3\, we show that this space is simply connected with non-positive curvature. This allows to get a description of the finite su bgroups of the 3-dimensional tame group. (Joint work with P. Przytycki) DTEND;TZID=Europe/Zurich:20190703T120000 END:VEVENT BEGIN:VEVENT UID:news899@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190624T131914 DTSTART;TZID=Europe/Zurich:20190626T150000 SUMMARY:PhD Defense Mathematics: Lars Bugiera DESCRIPTION:The talk is open to members of the university. X-ALT-DESC:The talk is open to members of the university. END:VEVENT BEGIN:VEVENT UID:news901@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190624T143705 DTSTART;TZID=Europe/Zurich:20190626T143000 SUMMARY:PhD Defense Computer Science: Dmytro Shulga DESCRIPTION:ABSTRACT:\\r\\nSolutions of Partial Differential Equations (PDE s) form the basis of many mathematical models\\r\\nin physics and medicine . In this work\, a novel Tensor B-spline methodology for numerical solutio ns of linear second-order PDEs is proposed. The methodology applies the B- spline signal processing framework and computational tensor algebra in ord er to construct high- performance numerical solvers for PDEs. The method a llows high-order approximations\, is mesh-free\, matrix-free and computati onally and memory efficient. The first chapter introduces the main ideas o f the Tensor B-spline method\, depicts the main contributions of the thesi s and outlines the thesis structure. The second chapter provides an introd uction to PDEs\, reviews the numerical methods for solving PDEs\, introduc es splines and signal processing techniques with B-splines\, and describes tensors and the computational tensor algebra. The third chapter describes the principles of the Tensor B-spline methodology. The main aspects are 1 ) discretization of the PDE variational formulation via B-spline represent ation of the solution\, the coefficients\, and the source term\, 2) introd uction to the tensor B-spline kernels\, 3) application of tensors and comp utational tensor algebra to the discretized variational formulation of the PDE\, 4) tensor-based analysis of the problem structure\, 5) derivation o f the efficient computational techniques\, and 6) efficient boundary proce ssing and numerical integration procedures. The fourth chapter describes 1 ) different computational strategies of the Tensor B-spline solver and an evaluation of their performance\, 2) the application of the method to the forward problem of the Optical Diffusion Tomography and an extensive compa rison with the state- of-the-art Finite Element Method on synthetic and re al medical data\, 3) high-performance multicore CPU- and GPU-based impleme ntations\, and 4) the solution of large-scale problems on hardware with li mited memory resources.\\r\\n\\r\\n\\r\\nThe talk is open to members of th e university. X-ALT-DESC:\nABSTRACT:\nSolutions of Partial Differential Equations (PDEs) form the basis of many mathematical models\nin physics and medicine. In th is work\, a novel Tensor B-spline methodology for numericalsolution s of linear second-order PDEs is proposed. The methodology applies the B-s pline

signal processing framework and computational tensor algebra i n order to construct high-

performance numerical solvers for PDEs. T he method allows high-order approximations\, is

mesh-free\, matrix-f ree and computationally and memory efficient.

The first chapter intr oduces the main ideas of the Tensor B-spline method\, depicts the main

contributions of the thesis and outlines the thesis structure.

Th e second chapter provides an introduction to PDEs\, reviews the numerical methods for

solving PDEs\, introduces splines and signal processing techniques with B-splines\, and describes

tensors and the computatio nal tensor algebra.

The third chapter describes the principles of th e Tensor B-spline methodology. The main

aspects are 1) discretizatio n of the PDE variational formulation via B-spline representation

of the solution\, the coefficients\, and the source term\, 2) introduction to the tensor B-spline

kernels\, 3) application of tensors and computa tional tensor algebra to the discretized variational

formulation of the PDE\, 4) tensor-based analysis of the problem structure\, 5) derivatio n of

the efficient computational techniques\, and 6) efficient bound ary processing and numerical

integration procedures.

The fourt h chapter describes 1) different computational strategies of the Tensor B- spline

solver and an evaluation of their performance\, 2) the applic ation of the method to the forward

problem of the Optical Diffusion Tomography and an extensive comparison with the state-

of-the-art Fi nite Element Method on synthetic and real medical data\, 3) high-performan ce

multicore CPU- and GPU-based implementations\, and 4) the solutio n of large-scale problems

on hardware with limited memory resources. \n\n\nThe talk is open to members of the university. END:VEVENT BEGIN:VEVENT UID:news833@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190529T183455 DTSTART;TZID=Europe/Zurich:20190529T141500 SUMMARY:Seminar Analysis: Mikaela Iacobelli (ETH Zürich) DESCRIPTION:The Vlasov-Poisson system is a kinetic equation that models col lisionless plasma. A plasma has a characteristic scale called the Debye le ngth\, which is typically much shorter than the scale of observation. In t his case the plasma is called ‘quasineutral’. This motivates studying the limit in which the ratio between the Debye length and the observation scale tends to zero. Under this scaling\, the formal limit of the Vlasov-P oisson system is the Kinetic Isothermal Euler system.The Vlasov-Poisson sy stem itself can formally be derived as the limit of a system of ODEs descr ibing the dynamics of a system of N interacting particles\, as the number of particles approaches infinity. The rigorous justification of this mean field limit remains a fundamental open problem.In this talk we present how the mean field and quasineutral limits can be combined to derive the Kine tic Isothermal Euler system from a regularised particle model. X-ALT-DESC:\nThe Vlasov-Poisson system is a kinetic equation that models co llisionless plasma. A plasma has a characteristic scale called the Debye l ength\, which is typically much shorter than the scale of observation. In this case the plasma is called ‘quasineutral’. This motivates studying the limit in which the ratio between the Debye length and the observation scale tends to zero. Under this scaling\, the formal limit of the Vlasov- Poisson system is the Kinetic Isothermal Euler system.

The Vlasov-Poi sson system itself can formally be derived as the limit of a system of ODE s describing the dynamics of a system of N interacting particles\, as the number of particles approaches infinity. The rigorous justification of thi s mean field limit remains a fundamental open problem.

In this talk w e present how the mean field and quasineutral limits can be combined to de rive the Kinetic Isothermal Euler system from a regularised particle model . DTEND;TZID=Europe/Zurich:20190529T160000 END:VEVENT BEGIN:VEVENT UID:news887@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190514T111137 DTSTART;TZID=Europe/Zurich:20190525T110000 SUMMARY:Seminar in Numerical Analysis: Florian Faucher (Université de Pau) DESCRIPTION:We study the inverse problem associated with the propagation of time-harmonic waves. In the seismic context\, the available measurements correspond with partial reflection data\, obtained from one side illuminat ion (only from the Earth surface). The inverse problem aims at recovering the subsurface Earth medium parameters and we employ the Full Waveform Inv ersion (FWI) method\, which relies on an iterative minimization algorithm of the difference between the measurement and simulation. \\r\\nWe investi gate the deployment of new devices developed in the acoustic setting: the dual-sensors\, which are able to capture both the pressure field and the v ertical velocity of the waves. For solving the inverse problem\, we define a new cost function\, adapted to these two types of data and based upon t he reciprocity. We first note that the stability of the problem can be sho wn to be Lipschitz\, assuming piecewise linear parameters. In addition\, r eciprocity waveform inversion allows a separation between the observationa l and numerical acquisitions. In fact\, the numerical sources do not have to coincide with the observational ones\, offering new possibilities to cr eate adapted computational acquisitions\, consequently reducing the numeri cal cost. We illustrate our approach with three-dimensional medium reconst ructions\, where we start with minimal information on the target models. W e also extend the methodology for elasticity. \\r\\nEventually\, if time a llows\, we shall explore the model representation in numerical seismic inv ersion\, where the adaptive eigenspace method appears as a promising appro ach to have a compromise between number of unknowns and resolution. \\r\\nReferences \\r\\n[1] G. Alessandrini\, M. V. de Hoop\, F. Faucher\, R. Gaburro and E. Sincich\, Inverse problem for the Helmholtz e quation with Cauchy data: reconstruction with conditional well-posedness d riven iterative regularization\, ESAIM: M2AN (2019). \\r\\n[2] E. Berett a\, M. V. De Hoop\, F. Faucher\, and O. Scherzer\, Inverse boundary value problem for the Helmholtz equation: quantitative conditional Lipschitz sta bility estimates. SIAM Journal on Mathematical Analysis\, 48(6)\, pp.3962- 3983 (2016).\\r\\n[3] M. J. Grote\, M. Kray\, and U. Nahum\, Adaptive ei genspace method for inverse scattering problems in the frequency domain. I nverse Problems\, 33(2)\, 025006 (2017). \\r\\n[4] H. Barucq\, F. Fauche r\, and O. Scherzer\, Eigenvector Model Descriptors for Solving an Inverse Problem of Helmholtz Equation. arXiv preprint arXiv:1903.08991 (2019).For further information about the seminar\, please visit this webpage. X-ALT-DESC:We study the inverse problem associated with the propagation of time-harmonic waves. In the seismic context\, the available measurements c orrespond with partial reflection data\, obtained from one side illuminati on (only from the Earth surface). The inverse problem aims at recovering t he subsurface Earth medium parameters and we employ the Full Waveform Inve rsion (FWI) method\, which relies on an iterative minimization algorithm o f the difference between the measurement and simulation. \nWe investigate the deployment of new devices developed in the acoustic setting: the dual- sensors\, which are able to capture both the pressure field and the vertic al velocity of the waves. For solving the inverse problem\, we define a ne w cost function\, adapted to these two types of data and based upon the re ciprocity. We first note that the stability of the problem can be shown to be Lipschitz\, assuming piecewise linear parameters. In addition\, recipr ocity waveform inversion allows a separation between the observational and numerical acquisitions. In fact\, the numerical sources do not have to co incide with the observational ones\, offering new possibilities to create adapted computational acquisitions\, consequently reducing the numerical c ost. We illustrate our approach with three-dimensional medium reconstructi ons\, where we start with minimal information on the target models. We als o extend the methodology for elasticity. \nEventually\, if time allows\, w e shall explore the model representation in numerical seismic inversion\, where the adaptive eigenspace method appears as a promising approach to ha ve a compromise between number of unknowns and resolution.

\nReferences \n[1] \;G. Alessandrini\, M. V. de Hoop\, F. Faucher\, R. Gaburro and E. Sincich\, Inverse problem for the Helmholtz e quation with Cauchy data: reconstruction with conditional well-posedness d riven iterative regularization\, ESAIM: M2AN (2019). \n[2] \;E. Beret ta\, M. V. De Hoop\, F. Faucher\, and O. Scherzer\, Inverse boundary value problem for the Helmholtz equation: quantitative conditional Lipschitz st ability estimates. SIAM Journal on Mathematical Analysis\, 48(6)\, pp.3962 -3983 (2016).\n[3] \;M. J. Grote\, M. Kray\, and U. Nahum\, Adaptive eigenspace method for inverse scattering problems in the frequency domain. Inverse Problems\, 33(2)\, 025006 (2017). \n[4] \;H. Barucq\, F. Fau cher\, and O. Scherzer\, Eigenvector Model Descriptors for Solving an Inve rse Problem of Helmholtz Equation. arXiv preprint arXiv:1903.08991 (2019).

For further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20190524T120000 END:VEVENT BEGIN:VEVENT UID:news890@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190523T151917 DTSTART;TZID=Europe/Zurich:20190523T170000 SUMMARY:Dr. Brian Amberg: Computer Vision and Machine Learning at Apple DESCRIPTION:Abstract The talk will present some of the successful projects at Apple where Computer Vision and Machine Learning was used. It will inc lude a deeper dive into the technology behind the real time facial motion capture on iPhone. Bio Dr. Brian Amberg studied „Information Science Co gnition“ in Freiburg i. Brsg. From 2005 until 2010\, he was a PhD in the research group of Prof. Dr. Vetter. In 2012\, Amberg co-founded at EPF L faceshift\, a startup specialised in motion capture technology. faceshif t was acquired in 2015 by Apple. X-ALT-DESC:

The talk will present some of the successf ul projects at Apple \;where Computer Vision and Machine Learning was used. It will include a deeper dive into the technology behind the real ti me facial motion capture on iPhone.

Dr. Bria n Amberg studied „Information Science Cognition“ in Freiburg i. Brsg. From 2005 until \;2010\, he \;was a \;PhD in the research grou p of Prof. Dr. Vetter. In 2012\, Amberg co-founded at EPFL

For further information about the seminar\, pleas e visit this webpage. DTEND;TZID=Europe/Zurich:20190517T120000 END:VEVENT BEGIN:VEVENT UID:news886@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092726 DTSTART;TZID=Europe/Zurich:20190516T121500 SUMMARY:Bernoullis Tafelrunde: Pascal Schmid DESCRIPTION:Abstract [t3://file?uid=1713] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20190516T130000 END:VEVENT BEGIN:VEVENT UID:news882@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190507T123529 DTSTART;TZID=Europe/Zurich:20190514T181500 SUMMARY:Studium! ... was dann? DESCRIPTION:"Data Science @ SBB"\\r\\n\\r\\nWie sieht Deine berufliche Zuku nft aus? Diese Vortragsreihe [t3://file?uid=1544]zeigt Dir spannende Karr ierewege.\\r\\nDer Vortrag findet um 18.15 Uhr im Seminarraum 00.003 in de r Spiegelgasse 1 (Departement Mathematik und Informatik) statt.\\r\\n\\r\\ nLink zum Plakat [t3://file?uid=1546] X-ALT-DESC:

Principal Scientist\, Computat ional Biology

Pharmaceutical Sciences\, Pharma Research and Early Dev elopment

Roche Innovation Center Basel\n

Senior Scientist\, Scientific Solution Engineering &\; Archite cture

Pharma Research and Early Development Informatics

Roche In novation Center Basel

HR Campu s Marketing Manager/University Relations

F. Hoffmann-La Roche Ltd.\n\ nAlle Vorträge sind auf Englisch und sind für Studierende der Mathematik \, Computer Science und Computational Science geeignet.\nDer anschliessend e Apéro findet im Foyer der Aula vom Kollegienhaus statt.\nLink zum Plak at\n\n\n END:VEVENT BEGIN:VEVENT UID:news862@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190425T114045 DTSTART;TZID=Europe/Zurich:20190510T171500 SUMMARY:BZ Seminar in Analysis: Mathieu Lewin (Paris Dauphine) DESCRIPTION:Density Functional Theory (DFT) is the main method used in prac tical computations to approximate solutions of the many-body Schrödinger equation. The main idea is to express everything in terms of the one-par ticle density instead of the many-body wave function. The Local Density A pproximation (LDA) is the simplest nonlinear functional used in this cont ext and it has played a central role in the construction of better empiri cal approximations since the 60s.In this talk I will first explain what D FT and LDA are. I will then give the first rigorous justification of the LDA. More precisely\, I will show that the exact Levy-Lieb functional of DFT converges to the LDA in the limit of very flat densities. Joint work with Elliott H. Lieb (Princeton) and Robert Seiringer (IST Austria). X-ALT-DESC:\nDensity Functional Theory (DFT) is the main method used in pra ctical \;computations to approximate solutions of the many-body Schrö dinger equation. \;The main idea is to express everything in terms of the one-particle density \;instead of the many-body wave function. The Local Density Approximation (LDA) \;is the simplest nonlinear functio nal used in this context and it has played a \;central role in the con struction of better empirical approximations since the \;60s.

In this talk I will first explain what DFT and LDA are. I will then giv e the \;first rigorous justification of the LDA. More precisely\, I wi ll show that the \;exact Levy-Lieb functional of DFT converges to the LDA in the limit of very \;flat densities. Joint work with Elliott H. Lieb (Princeton) and Robert \;Seiringer (IST Austria). DTEND;TZID=Europe/Zurich:20190510T181500 END:VEVENT BEGIN:VEVENT UID:news854@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190425T114048 DTSTART;TZID=Europe/Zurich:20190510T160000 SUMMARY:BZ Seminar in Analysis: Diego Cordoba (ICMAT Madrid) DESCRIPTION:I will discuss a new result on the existence of a stationary so lution with a fluid-squeezing singularity for the two-fluid incompressible Euler equations. The proof is based on a new set of estimates that perm its us to analyze a fluid squeezed by a self-intersecting interface. We wi ll exploit these estimates in the dynamical case and show a local existenc e result starting from a fluid-squeezing singularity. X-ALT-DESC:\nI will discuss a new result on the existence of a stationary s olution with a fluid-squeezing singularity for the two-fluid incompressibl e Euler equations. The proof is based on a new set of \;estimates tha t permits us to analyze a fluid squeezed by a self-intersecting interface. We will exploit these estimates in the dynamical case and show a local ex istence result starting from a fluid-squeezing singularity. DTEND;TZID=Europe/Zurich:20190510T170000 END:VEVENT BEGIN:VEVENT UID:news846@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190430T141302 DTSTART;TZID=Europe/Zurich:20190507T103000 SUMMARY:Seminar Algebra and Geometry: Yuri Prokhorov (Steklov Mathematical Institute\, Moscow) DESCRIPTION:A conic bundle f: X\\to S is a flat morphism of smooth varietie s whose fibers are plane conics. In this talk\, I will first discuss application of Sarkisov program to the rationality problem of algebraic varieties having conic bundle structures. Then I concentrate on some spec ial\, so-called tetragonal types of conic bundles\, which lie on the " boundary" between birationally rigid and non-rigid ones and are especiall y interesting for this reason. The second part of the talk is based on the joint work in progress with V. Shokurov. X-ALT-DESC:A conic bundle f: X\\to S is a flat morphism of smooth varieties whose \; fibers are plane conics. \; \;

In this talk\, I will first discuss application of \; Sarkisov program to the rational ity problem of algebraic varieties having conic bundle structures. \;< br />Then I concentrate on some special\, so-called \;

The second part of the talk is based on the joint work \;in progress with V. Shokurov. DTEND;TZID=Europe/Zurich:20190507T120000 END:VEVENT BEGIN:VEVENT UID:news865@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190502T110801 DTSTART;TZID=Europe/Zurich:20190506T180000 SUMMARY:Berufe nach dem Studium der Mathematik DESCRIPTION:In ihrem Vortrag (auf Englisch) erzählt Stephanie Meier-Rohr a us ihrem Berufsalltag.\\r\\nIm Anschluss daran sind alle herzlich zu einem kleinen Apéro eingeladen.\\r\\nLink zum Plakat [t3://file?uid=1677] X-ALT-DESC:In ihrem Vortrag (auf Englisch) erzählt Stephanie Meier-Rohr au s ihrem Berufsalltag.\nIm Anschluss daran sind alle herzlich zu einem klei nen Apéro eingeladen.\nLink zum Plakat\n\n\n END:VEVENT BEGIN:VEVENT UID:news861@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190423T105445 DTSTART;TZID=Europe/Zurich:20190503T110000 SUMMARY:Seminar in Numerical Analysis: Rémi Abgrall (Universität Zürich) DESCRIPTION:Since the work of B. Wendroff and P. Lax\, we know what should be the correct form of the numerical approximation of conservation law. W e also know\, after Hou and Le Floch\, what kind of problems we are facin g when the flux form is not respected. However\, this is not the end of the story. All these works use a one dimensional way of thinking: the mai n player is the normal flux across cell interfaces. In addition there are several excellent numerical methods that do not fit the form of the lax Wendroff theorem. In that talk\, I will introduce a more general setting and show that any reasonable scheme for conservation law can be put in th at framework. In addition\, I will show that an equivalent flux formulati on\, with a suitable definition of what is a flux\, can be explicitly c onstructed (and computed)\, so that any reasonable scheme can be put in a finite volume form. I will end the talk by showing some applications: h ow to systematically construct entropy stable scheme\, or starting from t he non conservative form of a system-say the Euler equations-\, how to construct a suitable discretisation. And more. This is a joint work with P. Bacigaluppi (now postdoc at ETH) and S. Tokareva (now at Los Alamos). For further information about the seminar\, please visit this webpage. X-ALT-DESC: Since the work of B. Wendroff and P. Lax\, we know what should be the correct form of the numerical approximation of conservation law. W e also know\, after Hou and Le Floch\, what kind of problems we are facin g when the flux form is not respected.

However\, this is not the end of the story. All these works use a one dimensional way of think ing: the main player is the normal flux across cell interfaces. In additi on there are several excellent numerical methods that do not fit the form of the lax Wendroff theorem.

In that talk\, I will introduce a more general setting and show that any reasonable scheme for conservat ion law can be put in that framework. In addition\, I will show that an e quivalent flux formulation\, with a suitable definition of what is a flux \, \; can be explicitly constructed (and computed)\, so that any reas onable scheme can be put in a finite volume form.

I will end the talk by showing some applications: how to systematically construct e ntropy stable scheme\, or starting from the non conservative form of \; a system-say the Euler equations-\, how to construct a suitable discre tisation. And more.

This is a joint work with P. Bacigaluppi (now postdoc at ETH) and S. Tokareva (now at Los Alamos).

For further information about the seminar\, please visit this webpage.

DTEND;TZID=Europe/Zurich:20190503T120000 END:VEVENT BEGIN:VEVENT UID:news866@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092733 DTSTART;TZID=Europe/Zurich:20190502T121500 SUMMARY:Bernoullis Tafelrunde: Simone Steinbrüchel DESCRIPTION:Abstract [t3://file?uid=1683] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20190502T130000 END:VEVENT BEGIN:VEVENT UID:news860@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092741 DTSTART;TZID=Europe/Zurich:20190425T121500 SUMMARY:Bernoullis Tafelrunde: Elise le Mélédo DESCRIPTION:Abstract [t3://file?uid=1650] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20190425T130000 END:VEVENT BEGIN:VEVENT UID:news856@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190410T101051 DTSTART;TZID=Europe/Zurich:20190424T141500 SUMMARY:Seminar Analysis: Giorgio Stefani (Scuola Normale Superiore di Pisa ) DESCRIPTION:Somewhat surprisingly\, the first appearance of the concept of a fractional derivative is found in a letter written to de l'Hôpital by L eibniz in 1695. Since then\, Fractional Calculus has fascinated generation s of mathematicians and several definitions of fractional derivatives have appeared. In more recent years\, the fractional operator defined as the g radient of the Riesz potential has received particular attention\, since i t has revealed to be a useful tool for the study of fractional-order PDEs and fractional Sobolev spaces. In a joint work with G. E. Comi\, combining the PDE approach developed by Spector and his collaborators with the dist ributional point of view adopted by Šilhavý\, we introduced new notions of fractional variation and fractional Caccioppoli perimeter in analogy w ith the classical BV theory. Within this framework\, we were able to parti ally extend De Giorgi’s Blow-up Theorem to sets of locally finite fracti onal Caccioppoli perimeter\, proving existence of blow-ups and giving a fi rst characterisation of these (possibly non-unique) limit sets. In this ta lk\, after a quick overview on Fractional Calculus\, I will introduce the main features of the fractional operators involved and then give an accoun t on the main results on the fractional variation we were able to achieve so far. X-ALT-DESC:\nSomewhat surprisingly\, the first appearance of the concept of a fractional derivative is found in a letter written to de l'Hôpital by Leibniz in 1695. Since then\, Fractional Calculus has fascinated generatio ns of mathematicians and several definitions of fractional derivatives hav e appeared. In more recent years\, the fractional operator defined as the gradient of the Riesz potential has received particular attention\, since it has revealed to be a useful tool for the study of fractional-order PDEs and fractional Sobolev spaces. In a joint work with G. E. Comi\, combinin g the PDE approach developed by Spector and his collaborators with the dis tributional point of view adopted by Šilhavý\, \;we introduced new n otions of fractional variation and fractional Caccioppoli perimeter in ana logy with the classical BV theory. Within this framework\, we were able to partially extend De Giorgi’s Blow-up Theorem to sets of locally finite fractional Caccioppoli perimeter\, proving existence of blow-ups and givin g a first characterisation of these (possibly non-unique) limit sets. In t his talk\, after a quick overview on Fractional Calculus\, I will introduc e the main features of the fractional operators involved and then give an account on the main results on the fractional variation we were able to ac hieve so far. DTEND;TZID=Europe/Zurich:20190424T160000 END:VEVENT BEGIN:VEVENT UID:news845@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190327T160809 DTSTART;TZID=Europe/Zurich:20190416T103000 SUMMARY:Seminar Algebra and Geometry: Matilde Manzaroli (École Polytechniq ue and Université de Nantes) DESCRIPTION:The study of the topology of real algebraic varieties dates bac k to the work of Harnack\, Klein and Hilbert in the 19th century\; in part icular\, the isotopy type classification of real algebraic curves with a f ixed degree in the real projective plane is a classical subject that has u ndergone considerable evolution. On the other hand\, apart from studies co ncerning Hirzebruch surfaces and at most degree 3 surfaces in the real pro jective space\, not much is known for more general ambient surfaces. In pa rticular\, this is because varieties constructed using the patchworking me thod are hypersurfaces of toric varieties. However\, there are many other real algebraic surfaces. Among these are the real rational surfaces\, and more particularly the real minimal surfaces. In this talk\, we present som e results about the classification of topological types realized by real a lgebraic curves in real minimal del Pezzo surfaces of degree. X-ALT-DESC:The study of the topology of real algebraic varieties dates back to the work of Harnack\, Klein and Hilbert in the 19th century\; in parti cular\, the isotopy type classification of real algebraic curves with a fi xed degree in the real projective plane is a classical subject that has un dergone considerable evolution. On the other hand\, apart from studies con cerning Hirzebruch surfaces and at most degree 3 surfaces in the real proj ective space\, not much is known for more general ambient surfaces. In par ticular\, this is because varieties constructed using the patchworking met hod are hypersurfaces of toric varieties. However\, there are many other r eal algebraic surfaces. Among these are the real rational surfaces\, and m ore particularly the real minimal surfaces. In this talk\, we present some results about the classification of topological types realized by real al gebraic curves in real minimal del Pezzo surfaces of degree. DTEND;TZID=Europe/Zurich:20190416T120000 END:VEVENT BEGIN:VEVENT UID:news857@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190402T151711 DTSTART;TZID=Europe/Zurich:20190412T110000 SUMMARY:Seminar in Numerical Analysis: Chris Stolk (University of Amsterdam ) DESCRIPTION:In this talk I discuss a recently developed finite difference d iscretisation of the Helmholtz equation and some solution methods for the resulting linear systems. In high-frequency Helmholtz problems\, pollution errors\, due to numerical dispersion\, are a main source of error. We wil l show that such errors can be strongly reduced compared to other schemes\ , including high-order finite elements\, by selecting coefficients for the discrete system that maximise the accuracy of geometrical optics phases a nd amplitudes. Such low dispersion schemes are of interest by themselves\, but can also be used to improve the efficiency of multigrid schemes. Comp utation times for a solver combining a multigrid method with domain decomp osition compare well to those of alternative methods.For further informati on about the seminar\, please visit this webpage. X-ALT-DESC: In this talk I discuss a recently developed finite difference d iscretisation of the Helmholtz equation and some solution methods for the resulting linear systems. In high-frequency Helmholtz problems\, pollution errors\, due to numerical dispersion\, are a main source of error. We wil l show that such errors can be strongly reduced compared to other schemes\ , including high-order finite elements\, by selecting coefficients for the discrete system that maximise the accuracy of geometrical optics phases a nd amplitudes. Such low dispersion schemes are of interest by themselves\, but can also be used to improve the efficiency of multigrid schemes. Comp utation times for a solver combining a multigrid method with domain decomp osition compare well to those of alternative methods.

For furth er information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20190412T120000 END:VEVENT BEGIN:VEVENT UID:news828@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190327T120936 DTSTART;TZID=Europe/Zurich:20190410T141500 SUMMARY:Seminar Analysis: Dominik Inauen (University of Zurich) DESCRIPTION:The problem of embedding abstract Riemannian manifolds isometri cally (i.e. preserving the lengths) into Euclidean space stems from the co nceptually fundamental question of whether abstract Riemannian manifolds a nd submanifolds of Euclidean space are the same. As it turns out\, such em beddings have a drastically different behaviour at low regularity (i.e. C^ 1) than at high regularity (i.e. C^2): for example\, it's possible to find C^1 isometric embeddings of the standard 2-sphere into arbitrarily small balls in R^3\, and yet\, in the C^2 category there is (up to translation a nd rotation) just one isometric embedding\, namely the standard inclusion. Analoguous to the Onsager conjecture\, one might ask if there is a regula rity threshold in the Hölder scale which distinguishes these behaviours. In my talk I will give an overview of what is known concerning the latter question. X-ALT-DESC:\nThe problem of embedding abstract Riemannian manifolds isometr ically (i.e. preserving the lengths) into Euclidean space stems from the c onceptually fundamental question of whether abstract Riemannian manifolds and submanifolds of Euclidean space are the same. As it turns out\, such e mbeddings have a drastically different behaviour at low regularity (i.e. C ^1) than at high regularity (i.e. C^2): for example\, it's possible to fin d C^1 isometric embeddings of the standard 2-sphere into arbitrarily small balls in R^3\, and yet\, in the C^2 category there is (up to translation and rotation) just one isometric embedding\, namely the standard inclusion . Analoguous to the Onsager conjecture\, one might ask if there is a regul arity threshold in the Hölder scale which distinguishes these behaviours. In my talk I will give an overview of what is known concerning the latter question. \; DTEND;TZID=Europe/Zurich:20190410T160000 END:VEVENT BEGIN:VEVENT UID:news855@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092749 DTSTART;TZID=Europe/Zurich:20190404T121500 SUMMARY:Bernoullis Tafelrunde: Benjamin Kessler DESCRIPTION:Abstract [t3://file?uid=1606] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20190404T130000 END:VEVENT BEGIN:VEVENT UID:news844@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190320T092425 DTSTART;TZID=Europe/Zurich:20190329T110000 SUMMARY:Seminar in Numerical Analysis: Robert Scheichl (Universität Heidel berg) DESCRIPTION:Sample-based multilevel uncertainty quantification tools\, such as multilevel Monte Carlo\, multilevel quasi-Monte Carlo or multilevel stochastic collocation\, have recently gained huge popularity due to thei r potential to efficiently compute robust estimates of quantities of inte rest (QoI) derived from PDE models that are subject to uncertainties in t he input data (coefficients\, boundary conditions\, geometry\, etc). Espe cially for problems with low regularity\, they are asymptotically optimal in that they can provide statistics about such QoIs at (asymptotically) the same cost as it takes to compute one sample to the target accuracy. H owever\, when the data uncertainty is localised at random locations\, suc h as for manufacturing defects in composite materials\, the cost per samp le can be reduced significantly by adapting the spatial discretisation in dividually for each sample. Moreover\, the adaptive process typically pro duces coarser approximations that can be used directly for the multilevel uncertainty quantification. In this talk\, I will present two novel deve lopments that aim to exploit these ideas. In the first part I will presen t Continuous Level Monte Carlo (CLMC)\, a generalisation of multilevel Mo nte Carlo (MLMC) to a continuous framework where the level parameter is a continuous variable. This provides a natural framework to use sample-wis e adaptive refinement strategy\, with a goal-oriented error estimator as our new level parameter. We introduce a practical CLMC estimator (and alg orithm) and prove a complexity theorem showing the same rate of complexit y as for MLMC. Also\, we show that it is possible to make the CLMC estima tor unbiased with respect to the true quantity of interest. Finally\, we provide two numerical experiments which test the CLMC framework alongsid e a sample-wise adaptive refinement strategy\, showing clear gains over a standard MLMC approach with uniform grid hierarchies. In the second part \, I will show how to extend the sample-adaptive strategy to multilevel s tochastic collocation (MLSC) methods providing a complexity estimate and numerical experiments for a MLSC method that is fully adaptive in the dim ension\, in the polynomial degrees and in the spatial discretisation. Thi s is joint work with Gianluca Detommaso (Bath)\, Tim Dodwell (Exeter) and Jens Lang (Darmstadt).For further information about the seminar\, please visit this webpage. X-ALT-DESC: Sample-based multilevel uncertainty quantification tools\, such as multilevel Monte Carlo\, multilevel quasi-Monte Carlo or multilevel stochastic collocation\, have recently gained huge popularity due to thei r potential to efficiently compute robust estimates of quantities of inte rest (QoI) derived from PDE models that are subject to uncertainties in t he input data (coefficients\, boundary conditions\, geometry\, etc). Espe cially for problems with low regularity\, they are asymptotically optimal in that they can provide statistics about such QoIs at (asymptotically) the same cost as it takes to compute one sample to the target accuracy. H owever\, when the data uncertainty is localised at random locations\, suc h as for manufacturing defects in composite materials\, the cost per samp le can be reduced significantly by adapting the spatial discretisation in dividually for each sample. Moreover\, the adaptive process typically pro duces coarser approximations that can be used directly for the multilevel uncertainty quantification. In this talk\, I will present two novel deve lopments that aim to exploit these ideas. In the first part I will presen t Continuous Level Monte Carlo (CLMC)\, a generalisation of multilevel Mo nte Carlo (MLMC) to a continuous framework where the level parameter is a continuous variable. This provides a natural framework to use sample-wis e adaptive refinement strategy\, with a goal-oriented error estimator as our new level parameter. We introduce a practical CLMC estimator (and alg orithm) and prove a complexity theorem showing the same rate of complexit y as for MLMC. Also\, we show that it is possible to make the CLMC estima tor unbiased with respect to the true quantity of interest. Finally\, we provide two numerical experiments which test the CLMC framework alongsid e a sample-wise adaptive refinement strategy\, showing clear gains over a standard MLMC approach with uniform grid hierarchies. In the second part \, I will show how to extend the sample-adaptive strategy to multilevel s tochastic collocation (MLSC) methods providing a complexity estimate and numerical experiments for a MLSC method that is fully adaptive in the dim ension\, in the polynomial degrees and in the spatial discretisation.

This is joint work with Gianluca Detommaso (Bath)\, Tim Dodwell (Exete r) and Jens Lang (Darmstadt).

For further information about the seminar\, please visit this webpage . DTEND;TZID=Europe/Zurich:20190329T120000 END:VEVENT BEGIN:VEVENT UID:news847@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092756 DTSTART;TZID=Europe/Zurich:20190328T121500 SUMMARY:Bernoullis Tafelrunde: Jonas Bayer DESCRIPTION:Abstract [t3://file?uid=1585]\, slides [t3://file?uid=1600] X-ALT-DESC: Abstract\, slides DTEND;TZID=Europe/Zurich:20190328T130000 END:VEVENT BEGIN:VEVENT UID:news830@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190327T081509 DTSTART;TZID=Europe/Zurich:20190327T141500 SUMMARY:Seminar Analysis: Tobias Weth (University of Frankfurt) DESCRIPTION:I will report on some recent results - obtained in joint work w ith Huyuan Chen - on Dirichlet problems for the Logarithmic Laplacian Oper ator\, which arises as formal derivative of fractional Laplacians at order s= 0. I will discuss the functional analytic framework for these problems and show how it allows to characterize the asymptotics of principal Diric hlet eigenvalues and eigenfunctions of fractional Laplacians as the order tends to zero. Furthermore\, I will discuss necessary and sufficient condi tions on domains giving rise to weak and strong maximum principles for the logarithmic Laplacian. If time permits\, I will also discuss regularity e stimates for solutions to corresponding Poisson problems. X-ALT-DESC:\nI will report on some recent results - obtained in joint work with Huyuan Chen - on Dirichlet problems for the Logarithmic Laplacian Ope rator\, which arises as formal derivative of fractional Laplacians at orde r s= 0. I will discuss the functional analytic framework for these problem s and show how it allows to characterize the asymptotics of principal Diri chlet eigenvalues and eigenfunctions of fractional Laplacians as the order tends to zero. Furthermore\, I will discuss necessary and sufficient cond itions on domains giving rise to weak and strong maximum principles for th e logarithmic Laplacian. If time permits\, I will also discuss regularity estimates for solutions to corresponding Poisson problems. DTEND;TZID=Europe/Zurich:20190327T160000 END:VEVENT BEGIN:VEVENT UID:news838@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092805 DTSTART;TZID=Europe/Zurich:20190321T121500 SUMMARY:Bernoullis Tafelrunde: Severin Schraven DESCRIPTION:Abstract [t3://file?uid=1571]\, slides [t3://file?uid=1580] X-ALT-DESC:Abstract\, slides DTEND;TZID=Europe/Zurich:20190321T130000 END:VEVENT BEGIN:VEVENT UID:news637@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190314T120420 DTSTART;TZID=Europe/Zurich:20190319T103000 SUMMARY:Seminar Algebra and Geometry: Mirko Mauri (Imperial College London) DESCRIPTION:The geometric P=W conjecture is a conjectural description of th e asymptotic behavior of a celebrated correspondence in non-abelian Hodge theory. In particular\, it is expected that the dual boundary complex of the compactification of character varieties is a sphere. In a joint wo rk with Enrica Mazzon and Matthew Stevenson\, we manage to compute the fi rst non-trivial examples of dual complexes in the compact case. This requ ires to develop a new theory of essential skeletons over a trivially-value d field. As a byproduct\, inspired by these constructions\, we show that certain character varieties appear in degenerations of compact hyper-Kä hler manifolds. In this talk we will explain how these new non-archime dean techniques can shed new light into classical algebraic geometry prob lems. X-ALT-DESC:The geometric P=W conjecture is a conjectural description of the asymptotic behavior of a celebrated correspondence in non-abelian Hodge&n bsp\;theory. In particular\, it is expected \;that the dual boundary&n bsp\;complex of the compactification of character varieties \;is a sph ere. In a joint work with Enrica Mazzon and Matthew Stevenson\, we manage to compute \;the first non-trivial \;examples of dual complexes in the compact case. This requires to develop a new theory of essential skel etons over a trivially-valued field. \;As a byproduct\, inspired by th ese constructions\, we show \;that certain character varieties appear in \;degenerations of compact hyper-Kähler manifolds. \; \;In this talk we will explain how these new \;non-archimedean techniques& nbsp\;can shed new light into classical algebraic geometry problems. \ ; DTEND;TZID=Europe/Zurich:20190319T120000 END:VEVENT BEGIN:VEVENT UID:news832@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092812 DTSTART;TZID=Europe/Zurich:20190307T131500 SUMMARY:Bernoullis Tafelrunde: Sokratis Zikas DESCRIPTION:Abstract [t3://file?uid=1555] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20190307T140000 END:VEVENT BEGIN:VEVENT UID:news831@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092821 DTSTART;TZID=Europe/Zurich:20190307T120500 SUMMARY:Bernoullis Tafelrunde: Pascal Fong DESCRIPTION:Abstract [t3://file?uid=1554] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20190307T125000 END:VEVENT BEGIN:VEVENT UID:news821@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190222T141344 DTSTART;TZID=Europe/Zurich:20190305T103000 SUMMARY:Seminar Algebra and Geometry: Federico Lo Bianco (Université de Ma rseille) DESCRIPTION:We consider a holomorphic (singular) foliation F on a projectiv e manifold X and a group G of birational transformations of X which preser ve F (i.e. it permutes the set of leaves). We say that the transverse acti on of G is finite if some finite index subgroup of G fixes each leaf of F. \\r\\nI will briefly recall a criterion for the finiteness of the transve rse action in the case of algebraically integrable foliations (i.e. foliat ions whose leaves coincide with the fibres of a fibration). Then I will ex plain how the presence of certain transverse structures on the foliation a llow to recover the same result\; in this case\, one can study the monodro my of such a structure (which is defined in an analogous way as that of a more familiar (G\,X)-structure) and apply factorization results in order t o reduce the problem to subvarieties of quotients of the product of unit d iscs\, whose geometry is now quite well understood. X-ALT-DESC:We consider a holomorphic (singular) foliation F on a projective manifold X and a group G of birational transformations of X which preserv e F (i.e. it permutes the set of leaves). We say that the transverse actio n of G is finite if some finite index subgroup of G fixes each leaf of F. \nI will briefly recall a criterion for the finiteness of the transverse a ction in the case of algebraically integrable foliations (i.e. foliations whose leaves coincide with the fibres of a fibration). Then I will explain how the presence of certain transverse structures on the foliation allow to recover the same result\; in this case\, one can study the monodromy of such a structure (which is defined in an analogous way as that of a more familiar (G\,X)-structure) and apply factorization results in order to red uce the problem to subvarieties of quotients of the product of unit discs\ , whose geometry is now quite well understood. DTEND;TZID=Europe/Zurich:20190305T120000 END:VEVENT BEGIN:VEVENT UID:news764@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T104547 DTSTART;VALUE=DATE:20190301 SUMMARY:Doktoratskolloquium Mathematik: Stefan Schmid DTEND;VALUE=DATE:20190228 END:VEVENT BEGIN:VEVENT UID:news829@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190225T091300 DTSTART;TZID=Europe/Zurich:20190301T110000 SUMMARY:Seminar in Numerical Analysis: Markus Zimmermann (Technische Univer sität München) DESCRIPTION:Solution spaces are sets of engineering solutions\, i.e.\, desi gns that satisfy all engineering requirements. Seeking solution spaces rat her than just one possibly optimal solution is numerically challenging\, b ut it can significantly simplify the development of systems in the presenc e of uncertainty and complexity. For different system components\, solutio n spaces are decomposed into independent target regions that enable distri buted development work and encompass uncertainty without particular underl ying uncertainty model. A basic stochastic algorithm to maximize so-called box-shaped solution spaces is presented. Two recent extensions are discus sed: first\, representations as Cartesian product of two- and higher-dimen sional spaces and\, second\, so-called solution-compensation spaces\, wher e design variables are grouped according to the order in which they need t o be specified. Applications to vehicle development for crash and driving dynamics are presented.For further information about the seminar\, please visit this webpage. X-ALT-DESC: Solution spaces are sets of engineering solutions\, i.e.\, desi gns that satisfy all engineering requirements. Seeking solution spaces rat her than just one possibly optimal solution is numerically challenging\, b ut it can significantly simplify the development of systems in the presenc e of uncertainty and complexity. For different system components\, solutio n spaces are decomposed into independent target regions that enable distri buted development work and encompass uncertainty without particular underl ying uncertainty model. A basic stochastic algorithm to maximize so-called box-shaped solution spaces is presented. Two recent extensions are discus sed: first\, representations as Cartesian product of two- and higher-dimen sional spaces and\, second\, so-called solution-compensation spaces\, wher e design variables are grouped according to the order in which they need t o be specified. Applications to vehicle development for crash and driving dynamics are presented.

For further information about the semin ar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20190301T120000 END:VEVENT BEGIN:VEVENT UID:news825@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;TZID=Europe/Zurich:20190228T141500 SUMMARY:Number Theory Seminar: Yuri Bilu (Université de Bordeaux) DESCRIPTION:The celebrated André-Oort conjecture about special point on Sh imura varieties is now proved conditionally to the GRH in full generality and unconditionally in many important special cases. In particular\, Pi la (2011) proved it for products of modular curves\, adapting a method p reviously developed by Pila and Zannier in the context of the Manin-Mumfo rd conjecture. Unfortunately\, Pila's argument is non-effective\, using t he Siegel-Brauer inequality. Since 2012 various special cases of the Andr é-Oort conjecture has been proved effectively\, most notably in the work of Lars Kühne. In my talk I will restrict to the case of the "Shimura v ariety" C^n and will try to explain on some simple examples how the effec tive approach of Kühne works. No previous knowledge about André-Oort co njecture is required\, I will give all the necessary background. X-ALT-DESC: The celebrated André-Oort conjecture about special point on Sh imura varieties is now proved conditionally to the GRH in full generality and unconditionally in many important special cases. In particular\, Pi la (2011) proved it for products of modular curves\, adapting a method p reviously developed by Pila and Zannier in the context of the Manin-Mumfo rd conjecture. Unfortunately\, Pila's argument is non-effective\, using t he Siegel-Brauer inequality.

Since 2012 various special cases of the André-Oort conjecture has been proved effectively\, most notably in the work of Lars Kühne. In my talk I will restrict to the case of the "\;Shimura variety"\; C^n and will try to explain on some simple examples how the effective approach of Kühne works.

No prev ious knowledge about André-Oort conjecture is required\, I will give all the necessary background. DTEND;TZID=Europe/Zurich:20190228T151500 END:VEVENT BEGIN:VEVENT UID:news826@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190220T080203 DTSTART;TZID=Europe/Zurich:20190226T121500 SUMMARY:Computer Science Colloquium: Dr. Etzard Stolte\, Global Head Knowle dge Management Roche\, Switzerland DESCRIPTION:Abstract:\\r\\nThe time to develop new drugs can be dramaticall y reduced through intelligent data-integration and re-use. To reduce this time by a factor of 10\, Roche Technical Development\, an organisation of 2500 colleagues\, has embraced a central information integration approach . In this talk I will present our vision and technology platform\, give an update on where we are on our journey\, and mention some of the barriers we encountered. \\r\\nOur approach to balance real world needs with accura cy and speed has gained some good success over the course of the last four years for a complex information landscape with hundreds of information en tities.\\r\\nSpeaker Bio:\\r\\nEtzard leads the global Information / Knowl edge Management effort in Pharma Technical Development for F. Hoffmann-La Roche in Basel\, with a focus on processes and tools for effective knowled ge utilisation. Etzard has worked at the interface of the Life- and Comput er-Sciences for more than 20 years\, in technical\, managerial as well as strategic roles. \\r\\nBefore joining Roche\, Etzard worked as CIO at the Jackson Lab (a US based genomics research institutes with 1800 employees)\ , and was CTO for the Life Sciences at Hewlett Packard. Etzard has earned academic degrees in Biology\, Bio-Informatics and Informatics\, with a PhD in Computer Science from ETH Zurich on “A Scalable Architecture for Sci entific Databases”.\\r\\nically and socially responsible participatory s haring economies. X-ALT-DESC:Abstract:\nThe time to develop new drugs can be dramatically red uced through intelligent data-integration and re-use. \;To reduce this time by a factor of 10\, Roche Technical Development\, an organisation of 2500 colleagues\, has embraced a central information integration approach . In this talk I will present our vision and technology platform\, give an update on where we are on our journey\, and mention some of the barriers we encountered. \nOur approach to balance real world needs with accuracy a nd speed has gained some good success over the course of the last four yea rs for a complex information landscape with hundreds of information entiti es.\nSpeaker Bio:\nEtzard leads the global Information / Knowledge Managem ent effort in Pharma Technical Development for F. Hoffmann-La Roche in Bas el\, with a focus on processes and tools for effective knowledge utilisati on. Etzard has worked at the interface of the Life- and Computer-Sciences for more than 20 years\, in technical\, managerial as well as strategic ro les. \nBefore joining Roche\, Etzard worked as CIO at the Jackson Lab (a U S based genomics research institutes with 1800 employees)\, and was CTO fo r the Life Sciences at Hewlett Packard. Etzard has earned academic degrees in Biology\, Bio-Informatics and Informatics\, with a PhD in Computer Sci ence from ETH Zurich on “A Scalable Architecture for Scientific Database s”.\nically and socially responsible participatory sharing economies.\n\ n DTEND;TZID=Europe/Zurich:20190226T140000 END:VEVENT BEGIN:VEVENT UID:news823@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190214T222417 DTSTART;TZID=Europe/Zurich:20190222T110000 SUMMARY:Seminar in Numerical Analysis: Edwin Mai (Universität der Bundesw ehr München) DESCRIPTION:With an increasing range of applications\, Shape Optimisation p roblems receive more and more interest in the engineering community\, whil e solving such problems is still a demanding task. In this talk the exampl e of a Stokes channel flow with the objective to reduce the energy dissipa tion is considered\, on which an optimise-then-discretize approach shall b e applied. Starting with a gradient descent method\, based on the analytic al shape derivative and the adjoint approach\, an initial optimisation pro cedure is discussed and differences in the shape derivative representation and their numerical implications are highlighted. Subsequently a possible way to derive shape hessian information in a so-called tangent-on-reverse method\, i.e. combining the adjoint and sensitivity approach\, is introdu ced. The shape hessian is utilised in a reduced SQP method for the equally constrained channel flow problem comprising of the objective\, PDE and ad ditional geometric constraints. In contrary to a one-shot approach the red uced approach requires the state and adjoint equations to be solved exactl y for each optimisation step. Finally\, some features of the numerical imp lementation using the finite element software package FEniCS and the obtai ned results are presented to show superiority of using hessian information .For further information about the seminar\, please visit this webpage. X-ALT-DESC: With an increasing range of applications\, Shape Optimisation p roblems receive more and more interest in the engineering community\, whil e solving such problems is still a demanding task. In this talk the exampl e of a Stokes channel flow with the objective to reduce the energy dissipa tion is considered\, on which an optimise-then-discretize approach shall b e applied. Starting with a gradient descent method\, based on the analytic al shape derivative and the adjoint approach\, an initial optimisation pro cedure is discussed and differences in the shape derivative representation and their numerical implications are highlighted. Subsequently a possible way to derive shape hessian information in a so-called tangent-on-reverse method\, i.e. combining the adjoint and sensitivity approach\, is introdu ced. The shape hessian is utilised in a reduced SQP method for the equally constrained channel flow problem comprising of the objective\, PDE and ad ditional geometric constraints. In contrary to a one-shot approach the red uced approach requires the state and adjoint equations to be solved exactl y for each optimisation step. Finally\, some features of the numerical imp lementation using the finite element software package FEniCS and the obtai ned results are presented to show superiority of using hessian information .

For further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20190222T120000 END:VEVENT BEGIN:VEVENT UID:news822@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190926T092828 DTSTART;TZID=Europe/Zurich:20190221T121500 SUMMARY:Bernoullis Tafelrunde: Ammar Yasir Kilic DESCRIPTION:Abstract [t3://file?uid=1460] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20190221T130000 END:VEVENT BEGIN:VEVENT UID:news635@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190122T113843 DTSTART;TZID=Europe/Zurich:20190206T161500 SUMMARY:80 Jahre Versicherungsmathematik an der Universität Basel DESCRIPTION:Mittwoch\, 6. Februar 2019\, ab 16:15\\r\\nJubiläumsveranstalt ung und Gründung AlumniActuarialScienceAm 6. Februar 1939 wurde Versicher ungslehre an der Universität Basel als selbständiges Examensfach eingef ührt. Anlässlich des 80jährigen Bestehens findet am Mittwoch\, 6. Febru ar 2019\, im Hörsaal 101 der Alten Universität eine Jubiläumsveranstalt ung [t3://file?uid=1331] statt mit Gründung der Fachalumni Actuarial Scie nce.\\r\\nAlle Interessierten sind herzlich eingeladen. Der Besuch der Ve ranstaltung ist von der SAV als Weiterbildung anerkannt (1 Credit Point SA V). \\r\\nAnmeldung für AlumniEssenFür die Vorträge und den anschliesse nden Apéro in der Alten Universität ist keine Anmeldung erforderlich. \\ r\\nDas AlumniEssen findet im Restaurant Zum Isaak statt und ist für Mitg lieder AlumniActuarialScience und solche\, die es gerne werden wollen. Bit te anmelden bis am 27. Januar 2019 an info@AlumniActuarialScience.ch [mail to:info@AlumniActuarialScience.ch]. \\r\\nAlumniActuarialScience werdenMit glied werden in der Fachalumni Actuarial Science können ehemalige Studier ende Actuarial Science/Versicherungsmathematik\, Dozierende und Emeriti\, SAV-Hörer*innen und alle am Studiengang interessierten Privatpersonen und Institutionen. \\r\\nWeitere Informationen: AlumniActuarialScience [t3:// page?uid=991]. X-ALT-DESC:

Am 6. Februar 1939 wurde Versicherungslehre an der Universität Basel als se lbständiges Examensfach eingeführt. Anlässlich des 80jährigen Bestehen s findet am Mittwoch\, 6. Februar 2019\, im Hörsaal 101 der Alten Univers ität eine Jubiläumsveranstaltung statt mit Gründung der Fachalumni Actuarial Science.\nAlle Interessierten sind herzlich eingeladen. Der Be such der Veranstaltung ist von der SAV als Weiterbildung anerkannt (1 Cred it Point SAV). \n

Für die Vorträge und den anschliessenden Apéro in der Alten Universität ist keine Anmeld ung erforderlich. \nDas AlumniEssen findet im Restaurant

Mitglied werden in der Fachalumni Actuarial Science können ehemalige St udierende Actuarial Science/Versicherungsmathematik\, Dozierende und Emeri ti\, SAV-Hörer*innen und alle am Studiengang interessierten Privatpersone n und Institutionen. \nWeitere Informationen: AlumniActuarialScience. DTEND;TZID=Europe/Zurich:20190206T190000 END:VEVENT BEGIN:VEVENT UID:news411@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181220T165902 DTSTART;TZID=Europe/Zurich:20181220T171500 SUMMARY:DMI-Colloquium: Dr. Florian Pommerening (University of Basel) DESCRIPTION:Dr. Florian Pommerening (Research Group Artificial Intelligence / Prof. Dr. Malte Helmert) was awarded for his PhD thesis with the facult y prize of the Faculty of Science at this year's Dies Academicus.\\r\\nThe re will be an apero after the talk. X-ALT-DESC:

Dr. Florian Pommerening (Research Group Artificial Intelli gence / Prof. Dr. Malte Helmert) was awarded for his PhD thesis with the f aculty prize of the Faculty of Science at this year's Dies Academicus.

Computer security is no longer about dat a\; it's about life and property. This change makes an enormous difference \, and will shake up our industry in many ways. First\, data authenticatio n and integrity will become more important than confidentiality. And secon d\, our largely regulation-free Internet will become a thing of the past. Soon we will no longer have a choice between government regulation and no government regulation. Our choice is between smart government regulation a nd stupid government regulation. Given this future\, it's vital that we lo ok back at what we've learned from past attempts to secure these systems\, and forward at what technologies\, laws\, regulations\, economic incentiv es\, and social norms we need to secure them in the future.\n

Bruce Schneier is an internationally renowned security technol ogist\, called a security guru by the Economist. He is the author of 14 bo oks -- including the best-seller Click Here to Kill Everybody -- as well a s hundreds of articles\, essays\, and academic papers. His influential new sletter Crypto-Gram and blog Schneier on Security are read by over

25 0\,000 people. Schneier is a fellow at the Berkman Klein Center for Intern et and Society at Harvard University\; a Lecturer in Public Policy at the Harvard Kennedy School\; a board member of the Electronic Frontier Foundat ion\, AccessNow\, and the Tor Project\; and an advisory board member of EP IC and VerifiedVoting.org. He is also a special advisor to IBM Security an d the Chief Technology Officer of IBM Resilient.\n\n END:VEVENT BEGIN:VEVENT UID:news355@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181030T094303 DTSTART;TZID=Europe/Zurich:20181212T110000 SUMMARY:Seminar in probability theory: Ioan Manolescu (Fribourg) DESCRIPTION:TBA X-ALT-DESC:TBA END:VEVENT BEGIN:VEVENT UID:news410@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T082628 DTSTART;TZID=Europe/Zurich:20181211T103000 SUMMARY:Seminar Algebra and Geometry: Luca Studer (University of Bern) DESCRIPTION:In the talk we discuss how Oka theory helps to solve systems of equations with complex analytic entries. A classical example is the fact that for every pair of complex analytic functions a\, b: C^n -> C with no common zero there are complex analytic functions x\, y: C^n -> C satisfyin g the Bézout identity ax+by=1. A more recent example is Leiterer's work\, where the solvability of xax^{-1}=b for complex analytic matrix-valued ma ps a\, b: C^n -> Mat(n x n\, C) is investigated. Both examples are brought into the context of the speakers research. X-ALT-DESC:In the talk we discuss how Oka theory helps to solve systems of equations with complex analytic entries. A classical example is the fact t hat for every pair of complex analytic functions a\, b: C^n ->\; C with no common zero there are complex analytic functions x\, y: C^n ->\; C sa tisfying the Bézout identity ax+by=1. A more recent example is Leiterer's work\, where the solvability of xax^{-1}=b for complex analytic matrix-va lued maps a\, b: C^n ->\; Mat(n x n\, C) is investigated. Both examples are brought into the context of the speakers research. DTEND;TZID=Europe/Zurich:20181211T120000 END:VEVENT BEGIN:VEVENT UID:news409@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181203T104240 DTSTART;TZID=Europe/Zurich:20181207T110000 SUMMARY:Seminar in Numerical Analysis: Zakaria Belhachmi (LMIA - Universit é de Haute-Alsace) DESCRIPTION:We present some ideas on modelling with diffusion operators so me PDEs based geometry inpainting problems. The objective is to provide a closed loop continuous to discrete models. The loop consists of an initi al family of simple PDEs depending on some parameters selected at the dis crete level from a posteriori informations. The choice of these parameter s modify dynamically the system of equations and the resulting models con verge (in the Gamma-convergence sense) to a limit -continuous- model that capture the jump set of the restaured image. We also discuss the compress ion-based inpainting within this approach.For further information about t he seminar\, please visit this webpage. X-ALT-DESC: We present some ideas on modelling with diffusion operators so me PDEs based geometry inpainting problems. The objective is to provide a closed loop continuous to discrete models. The loop consists of an initi al family of simple PDEs depending on some parameters selected at the dis crete level from a posteriori informations. The choice of these parameter s modify dynamically the system of equations and the resulting models con verge (in the Gamma-convergence sense) to a limit -continuous- model that capture the jump set of the restaured image. We also discuss the compress ion-based inpainting within this approach.

For further informa tion about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20181207T120000 END:VEVENT BEGIN:VEVENT UID:news395@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181203T170020 DTSTART;TZID=Europe/Zurich:20181206T121500 SUMMARY:Bernoullis Tafelrunde: Philippe Wenk DESCRIPTION:Abstract [t3://file?uid=1364] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20181206T130000 END:VEVENT BEGIN:VEVENT UID:news348@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T083213 DTSTART;TZID=Europe/Zurich:20181204T103000 SUMMARY:Seminar Algebra and Geometry: Bruno Laurent (Grenoble) DESCRIPTION:The varieties which are homogeneous under the action of an alge braic group are very symmetric objects. More generally\, we get a much wid er class of objects\, having a very rich geometry\, by allowing the variet ies to have not a unique orbit\, but a dense orbit. Such varieties are sai d to be almost homogeneous\; this includes the case of toric varities\, wh en the group is an algebraic torus.In this talk\, I will explain how to cl assify the pairs (X\,G) where X is a curve or a surface and G is a smo oth and connected algebraic group acting on X with a dense orbit.For cur ves\, I will mainly focus on the regular ones\, defined over an arbitrary field. Over an algebraically closed field\, the "natural" notion of non-si ngularity is "smoothness". However\, over an arbitrary field\, the weaker notion of "regularity" is more suitable. I will recall the difference betw een those two notions and show that there exist regular homogeneous curves which are not smooth.For surfaces\, I will restrict to the smooth ones\, defined over an algebraically closed field. The situation is more complica ted than for curves. Moreover\, new phenomena and several difficulties app ear in positive characteristic\, and I will highlight them. X-ALT-DESC:The varieties which are homogeneous under the action of an algeb raic group are very symmetric objects. More generally\, we get a much wide r class of objects\, having a very rich geometry\, by allowing the varieti es to have not a unique orbit\, but a dense orbit. Such varieties are said to be almost homogeneous\; this includes the case of toric varities\, whe n the group is an algebraic torus.

In this talk\, I will explai n how to classify the pairs (X\,G) where \;X \;is a curve or a sur face and \;G \;is a smooth and connected algebraic group acting on \;X \;with a dense orbit.

For curves\, I will mainly f ocus on the regular ones\, defined over an arbitrary field. Over an algebr aically closed field\, the "\;natural"\; notion of non-singularity is "\;smoothness"\;. However\, over an arbitrary field\, the weak er notion of "\;regularity"\; is more suitable. I will recall the difference between those two notions and show that there exist regular hom ogeneous curves which are not smooth.

For surfaces\, I will res trict to the smooth ones\, defined over an algebraically closed field. The situation is more complicated than for curves. Moreover\, new phenomena a nd several difficulties appear in positive characteristic\, and I will hig hlight them. DTEND;TZID=Europe/Zurich:20181204T120000 END:VEVENT BEGIN:VEVENT UID:news321@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;TZID=Europe/Zurich:20181129T141500 SUMMARY:Number Theory Seminar: Ana Maria Botero (Univ. of Regensburg) DTEND;TZID=Europe/Zurich:20181129T151500 END:VEVENT BEGIN:VEVENT UID:news377@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T134044 DTSTART;TZID=Europe/Zurich:20181129T121500 SUMMARY:Bernoullis Tafelrunde: André Opris DESCRIPTION:Abstract [t3://file?uid=1264]\, slides [t3://file?uid=1388] X-ALT-DESC:Abstract\, slides DTEND;TZID=Europe/Zurich:20181129T130000 END:VEVENT BEGIN:VEVENT UID:news329@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T174428 DTSTART;TZID=Europe/Zurich:20181128T141500 SUMMARY:Seminar Analysis: Stefano Spirito (Università dell'Aquila) DESCRIPTION:In this talk I will present some results concerning the analysi s of finite energy weak solutions of the Navier-Stokes-Korteweg equations\ , which model the dynamic of a viscous compressible fluid with diffuse int erface. A general theory of global existence is still missing\, however for some particular cases of physical interest I will present results rega rding the global existence and the compactness of finite energy weak solut ions. The talk is based on a series of joint works with Paolo Antonelli (G SSI - Gran Sasso Science Institute\, L’Aquila). X-ALT-DESC:\nIn this talk I will present some results concerning the analys is of finite energy weak solutions of the Navier-Stokes-Korteweg equations \, which model the dynamic of a viscous compressible fluid with diffuse in terface. \;A general theory of global existence is still missing\, ho wever for some particular cases of physical interest I will present result s regarding the global existence and the compactness of finite energy weak solutions. The talk is based on a series of joint works with Paolo Antone lli (GSSI - Gran Sasso Science Institute\, L’Aquila). DTEND;TZID=Europe/Zurich:20181128T160000 END:VEVENT BEGIN:VEVENT UID:news354@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181030T094136 DTSTART;TZID=Europe/Zurich:20181128T110000 SUMMARY:Seminar in probability theory: Gaultier Lambert (University of Zuri ch) DESCRIPTION:TBA X-ALT-DESC:TBA END:VEVENT BEGIN:VEVENT UID:news339@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T163958 DTSTART;TZID=Europe/Zurich:20181123T161500 SUMMARY:Buchpräsentation des Bernoulli-Euler-Zentrums: Der Briefwechsel Le onhard Eulers mit Korrespondenten aus dem Umfeld der Universiät Halle (17 41 - 1771) DESCRIPTION:16:15Vortrag von Thomas Steiner\, Basel:Briefe Johann Andreas v on Segners an Leonhard Euler:Streiflichter auf Leben und Werk des "Vaters der Turbine"17:15Apéro mit Präsentation eines neuen Bandes der Euler-Edi tion durch das Bernoulli-Euler-Zentrum\, das Departement Mathematik und In formatik der Universität Basel und Birkhäuser BaselLeonhardi Euleri Oper a Omnia\, Bd. IVA/8:Briefwechsel mit Th. Abbt\, B. Brauser\, J.P. Eberhard \, F.Ch. Jetze\, W.J.G. Karsten\, Ch.A. Körber\,Ch.G. Kratzenstein\, J.G. Krüger\, J.J. Lange\, J.A. Osiander\, J.E. Philippi\, J.H. Schulze\, J.A . von Segner und J.W. von SegnerHerausgegeben von Andreas Kleinert und Tho mas Steiner18:15Vortrag von Andreas Kleinert\, Halle/Saale:Eulers hallesch e Korrespondenten\\r\\n\\r\\nFlyer [t3://file?uid=1073] X-ALT-DESC:

16:15 | Vortrag von Thomas Steine
r\, Basel: |

17:15 | Apéro mit Präsentation e ines neuen Bandes der Euler-Edition durch das Bernoulli-Euler-Zentrum\, da s Departement Mathematik und Informatik der Universität Basel und Birkhä user Basel Leonhardi Euleri Opera Omnia\, Bd. IVA/8: Herausgegeben von Andreas Klei
nert und Thomas Steiner |

18:15 | Vortrag von
Andreas Kleinert\, Halle/Saale:Eulers hallesche Korrespondenten<
/i> |

In the second part of t he talk\, we will discuss a Bayesian approach for inverse problems involv ing elliptic partial differential equations with multiple scales. Computi ng repeated forward problems in a multiscale context is computationnally too expensive and we propose a new strategy \;based on the use of&nb sp\; "\;effective"\; forward models originating from homogenizati on theory. Convergence of the true posterior distribution for the paramet ers of interest towards the homogenized posterior is established via G-co nvergence for the Hellinger metric. A computational approach based on num erical homogenization and reduced basis methods is proposed for an effici ent evaluation of the forward model in a Markov Chain Monte-Carlo proced ure. \;

References:

A. Abdulle\, G. Garegnani\, R andom time step probabilistic methods for uncertainty quantification in c haotic and geometric numerical integration\, Preprint (2018)\, submitted for publication.

A. Abdulle\, A. Di Blasio\, Numerical homogenizati on and model order reduction for multiscale inverse problems\, to appear in SIAM MMS.

A. Abdulle\, A. Di Blasio\, A Bayesian numerical homog enization method for elliptic multiscale inverse problems\, Preprint (201 8)\, submitted for publication.

For further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20181123T120000 END:VEVENT BEGIN:VEVENT UID:news320@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;TZID=Europe/Zurich:20181122T141500 SUMMARY:Number Theory Seminar: Amador Martin-Pizarro (Univ. of Freiburg) DESCRIPTION:Lascar showed that the group of automorphisms of the complex fi eld which fix the algebraic closure of the prime field is simple. For this \, he first showed that there are no non-trivial bounded automorphisms. An automorphism is bounded if there is a finite set A such that the image of every element b is algebraic over A together with b. The same result hold s for a "universal" differentially closed field of characteristic zero\, w here we replace algebraic by differentially algebraic. Together with T. Bl ossier and C. Hardouin\, we provided in https://arxiv.org/abs/1505.03669 [ https://arxiv.org/abs/1505.03669] a complete classification of bounded aut omorphisms in various fields equipped with operators\, among others\, for generic difference fields in all characteristics or for Hasse-Schmidt diff erential fields in positive characteristic. X-ALT-DESC: Lascar showed that the group of automorphisms of the complex fi eld which fix the algebraic closure of the prime field is simple. For this \, he first showed that there are no non-trivial bounded automorphisms. An automorphism is bounded if there is a finite set A such that the image of every element b is algebraic over A together with b. The same result hold s for a "\;universal"\; differentially closed field of characteris tic zero\, where we replace algebraic by differentially algebraic. Togethe r with T. Blossier and C. Hardouin\, we provided in https://arxiv.org/abs/1505.03669 a complete class ification of bounded automorphisms in various fields equipped with operato rs\, among others\, for generic difference fields in all characteristics o r for Hasse-Schmidt differential fields in positive characteristic. DTEND;TZID=Europe/Zurich:20181122T151500 END:VEVENT BEGIN:VEVENT UID:news394@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181119T150248 DTSTART;TZID=Europe/Zurich:20181122T121500 SUMMARY:Bernoullis Tafelrunde: Eva Schnider DESCRIPTION:Abstract [t3://file?uid=1293] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20181122T130000 END:VEVENT BEGIN:VEVENT UID:news95@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T174437 DTSTART;TZID=Europe/Zurich:20181121T141500 SUMMARY:Seminar Analysis: Elia Bruè (Scuola Normale Superiore di Pisa) DESCRIPTION:Since the work by DiPerna and Lions (1989) the continuity and t ransport equation under mild regularity assumptions on the vector field ha ve been extensively studied\, becoming a florid research field. The applic ability of this theory is very wide\, especially in the study of partial d ifferential equations and very recently also in the field of non-smooth ge ometry.\\r\\nThe aim of this talk is to give an overview of the quantitati ve side of the theory initiated by Crippa and De Lellis. We address the pr oblem of mixing and propagation of regularity for solutions to the continu ity equation drifted by Sobolev fields. The problem is well understood whe n the vector field enjoys a Sobolev regularity with integrability exponent p>1 and basically nothing is known (at the quantitative level) in the cas e p=1.\\r\\nWe present sharp regularity estimates for the case p>1 and new attempts to attack the challenging question in the case p=1. This is a jo in work with Quoc-Hung Nguyen. X-ALT-DESC:\nSince the work by DiPerna and Lions (1989) the continuity and transport equation under mild regularity assumptions on the vector field h ave been extensively studied\, becoming a florid research field. The appli cability of this theory is very wide\, especially in the study of partial differential equations and very recently also in the field of non-smooth g eometry.\nThe aim of this talk is to give an overview of the quantitative side of the theory initiated by Crippa and De Lellis. We address the probl em of mixing and propagation of regularity for solutions to the continuity equation drifted by Sobolev fields. The problem is well understood when t he vector field enjoys a Sobolev regularity with integrability exponent p& gt\;1 and basically nothing is known (at the quantitative level) in the ca se p=1.\nWe present sharp regularity estimates for the case p>\;1 and ne w attempts to attack the challenging question in the case p=1. This is a j oin work with Quoc-Hung Nguyen. DTEND;TZID=Europe/Zurich:20181121T160000 END:VEVENT BEGIN:VEVENT UID:news326@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181103T093011 DTSTART;TZID=Europe/Zurich:20181121T110000 SUMMARY:Seminar in probability theory: Antti Knowles (Geneva) DESCRIPTION:We consider the adjacency matrix of the Erdos-Renyi graph G(N\, p) in the supercritical regime pN > C log N for some universal constant C . We show that the eigenvalue density is with high probability well appr oximated by the semicircle law on all spectral scales larger than the typ ical eigenvalue spacing. We also show that all eigenvectors are completel y delocalized with high probability. Both results are optimal in the sens e that they are known to be false for pN < log N. A key ingredient of the proof is a new family of large deviation estimates for multilinear forms of sparse vectors. \\r\\nJoint work with Yukun He and Matteo Marcozzi. X-ALT-DESC: We consider the adjacency matrix of the Erdos-Renyi graph G(N\, p) in the supercritical regime pN >\; C log N for some universal consta nt C. We show that the eigenvalue density is with high probability well approximated by the semicircle law on all spectral scales larger than the typical eigenvalue spacing. We also show that all eigenvectors are compl etely delocalized with high probability. Both results are optimal in the sense that they are known to be false for pN <\; log N. A key ingredien t of the proof is a new family of large deviation estimates for multiline ar forms of sparse vectors. \nJoint work with Yukun He and Matteo Marcozz i. END:VEVENT BEGIN:VEVENT UID:news341@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T082628 DTSTART;TZID=Europe/Zurich:20181120T103000 SUMMARY:Seminar Algebra and Geometry: Nikon Kurnosov (University of Georgia \, Athens\, US) DESCRIPTION:Hyperkähler manifolds are higher-dimensional generalizations o f K3 surfaces. The Beauville conjecture predicts that the number of deform ation types of compact irreducible hyperkähler manifolds is finite in any dimension. In this talk I will briefly discuss some basic notions of the theory\, explain why hyperkähler manifolds play a very important role in classification of complex manifolds\, and then explain what are the eviden ces for Beauville's conjecture. X-ALT-DESC:Hyperkähler manifolds are higher-dimensional generalizations of K3 surfaces. The Beauville conjecture predicts that the number of deforma tion types of compact irreducible hyperkähler manifolds is finite in any dimension. In this talk I will briefly discuss some basic notions of the t heory\, explain why hyperkähler manifolds play a very important role in c lassification of complex manifolds\, and then explain what are the evidenc es for Beauville's conjecture. DTEND;TZID=Europe/Zurich:20181120T120000 END:VEVENT BEGIN:VEVENT UID:news307@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181024T123048 DTSTART;TZID=Europe/Zurich:20181116T113000 SUMMARY:Seminar in Numerical Analysis: Ludovic Métivier (Université Greno ble Alpes) DESCRIPTION:Full waveform inversion (FWI) is a powerful high resolution sei smic imaging method\, used in the academy for global and regional scale imaging\, and in the oil & gas industry for exploration purposes. It can be understood as a PDE constrained optimization problem: the misfit betwe en recorded seismic data and synthetic seismic data computed as the solut ion of a wave propagation problem is reduced over a space of parameters c ontrolling the wave propagation. One of the main limitation of FWI is its dependency on the accuracy of the initial guess of the solution. This li mitation is due to the non-convexity of the standard least-squares misfit function used to measure the discrepancy between recorded and synthetic data\, and the use of local optimization techniques to reduce this misfi t. In recent studies\, we have studied the interest for using a misfit fu nction based on an optimal transport distance to mitigate this issue. The convexity of this distance with respect to shifted patterns is the main reason why we are interested in this distance\, as it can be seen as a pr oxy for the convexity with respect to the wave velocities we want to re construct. In this talk\, we will give an overview of this work\, startin g by introducing basic concepts on optimal transport\, before detailing the difficulties for using the optimal transport distance in the framewor k of FWI\, and reviewing the solutions we have proposed.\\r\\nFor further information about the seminar\, please visit this webpage. X-ALT-DESC: Full waveform inversion (FWI) is a powerful high resolution sei smic imaging method\, used in the academy for global and regional scale imaging\, and in the oil &\; gas industry for exploration purposes. It can be understood as a PDE constrained optimization problem: the misfit between recorded seismic data and synthetic seismic data computed as the solution of a wave propagation problem is reduced over a space of paramet ers controlling the wave propagation. One of the main limitation of FWI i s its dependency on the accuracy of the initial guess of the solution. Th is limitation is due to the non-convexity of the standard least-squares m isfit function used to measure the discrepancy between recorded and synt hetic data\, and the use of local optimization techniques to reduce this misfit. In recent studies\, we have studied the interest for using a misf it function based on an optimal transport distance to mitigate this issue . The convexity of this distance with respect to shifted patterns is the main reason why we are interested in this distance\, as it can be seen as a proxy for the convexity with respect to the wave velocities we want to \; reconstruct. In this talk\, we will give an overview of this work \, starting by introducing basic concepts on optimal transport\, before d etailing the difficulties for using the optimal transport distance in the framework of FWI\, and reviewing the solutions we have proposed.\nFor fu rther information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20181116T123000 END:VEVENT BEGIN:VEVENT UID:news376@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175648 DTSTART;TZID=Europe/Zurich:20181115T121500 SUMMARY:Bernoullis Tafelrunde: Carlo Seppi DESCRIPTION:Abstract [t3://file?uid=1261] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20181115T130000 END:VEVENT BEGIN:VEVENT UID:news353@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181103T092837 DTSTART;TZID=Europe/Zurich:20181114T110000 SUMMARY:Seminar in probability theory: Marius Schmidt (Basel) DESCRIPTION:Consider the hypercube as a graph with vertex set {0\,1}^N and edges between two vertices if they are only one coordinate flip apart. C hoosing independent standard exponentially distributed lengths for all ed ges and asking how long the shortest directed paths from (0\,..\,0) to (1 \,..\,1) is defines oriented first passage percolation on the hypercube. We will discuss the conceptual steps needed to answer this question to th e precision of extremal process following the two paper series "Oriented first passage percolation in the mean field limit" by Nicola Kistler\, Ad rien Schertzer and Marius A. Schmidt: arXiv:1804.03117 and arXiv:1808.0459 8. X-ALT-DESC: Consider the hypercube as a graph with vertex set {0\,1}^N and edges between two vertices if they are only one coordinate flip apart. C hoosing independent standard exponentially distributed lengths for all ed ges and asking how long the shortest directed paths from (0\,..\,0) to (1 \,..\,1) is defines oriented first passage percolation on the hypercube. We will discuss the conceptual steps needed to answer this question to th e precision of extremal process following the two paper series "\;Ori ented first passage percolation in the mean field limit"\; by Nicola Kistler\, Adrien Schertzer and Marius A. Schmidt: arXiv:1804.03117 and arX iv:1808.04598. END:VEVENT BEGIN:VEVENT UID:news361@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T082628 DTSTART;TZID=Europe/Zurich:20181113T103000 SUMMARY:Seminar Algebra and Geometry: Lukas Lewark (University of Bern) DESCRIPTION:This talk will explore different notions of positivity of knots \, how to encode such knots as graphs\, and how to unknot them. Joint resu lts with Baader/Liechti and Feller/Lobb will make appearances. No prerequi sites in knot theory will be necessary. X-ALT-DESC:This talk will explore different notions of positivity of knots\ , how to encode such knots as graphs\, and how to unknot them. Joint resul ts with Baader/Liechti and Feller/Lobb will make appearances. No prerequis ites in knot theory will be necessary. DTEND;TZID=Europe/Zurich:20181113T120000 END:VEVENT BEGIN:VEVENT UID:news359@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181031T192501 DTSTART;TZID=Europe/Zurich:20181109T110000 SUMMARY:Seminar in Numerical Analysis: Stefan Sauter (Universität Zürich) DESCRIPTION:In our talk we consider the Maxwell equations in the frequency domain\, discretized by Nédélec-hp-finite elements. We develop a stabili ty and convergence analysis which is explicit with respect to the wave nu mber k\, the mesh size h\, and the local polynomial degree p. It turns ou t that\, for the choice p>=log(k) \, the discretization does not suffer f rom the so-called pollution effect. This is known for high-frequency acous tic scattering. However\, the analysis of Maxwell equations requires the development of twelve additional theoretical tools which we call "the twel ve apostels". In our talk\, we explain these "apostels" and how they are n eeded to prove the stability and convergence of our method.\\r\\nThis tal k comprises joint work with Prof. Markus Melenk\, TU Wien. \\r\\nFor furth er information about the seminar\, please visit this webpage. X-ALT-DESC: In our talk we consider the Maxwell equations in the frequency domain\, discretized by Nédélec-hp-finite elements. We develop a stabili ty and convergence analysis which is explicit with respect to the wave nu mber k\, the mesh size h\, and the local polynomial degree p. It turns ou t that\, for the choice p>\;=log(k) \, the discretization does not suff er from the so-called pollution effect. This is known for high-frequency a coustic scattering. However\, the analysis of Maxwell equations requires the development of twelve additional theoretical tools which we call " \;the twelve apostels"\;. In our talk\, we explain these "\;aposte ls"\; and how they are needed to prove the stability and convergence of our method.\nThis talk comprises joint work with Prof. Markus Melenk\, TU Wien. \nFor further information about the seminar\, please visit this < link de/forschung/mathematik/seminar-in-numerical-analysis/ - - "Opens int ernal link in current window">webpage. DTEND;TZID=Europe/Zurich:20181109T120000 END:VEVENT BEGIN:VEVENT UID:news346@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T174842 DTSTART;TZID=Europe/Zurich:20181108T161500 SUMMARY:Computer Science Colloquium: Dr. Evangelos Pournaras\, ETH Zürich DESCRIPTION:Abstract:\\r\\nThe Internet of Things equips citizens with phen omenal new means for online participation in sharing economies. When agent s self-determine options from which they choose\, for instance their resou rce consumption and production\, while these choices have a collective sys tem-wide impact\, optimal decision-making turns into a combinatorial optim ization problem known as NP-hard. In such challenging computational proble ms\, centrally managed (deep) learning systems often require personal data with implications on privacy and citizens’ autonomy. This paper envisio ns an alternative unsupervised and decentralized collective learning appro ach that preserves privacy\, autonomy and participation of multi-agent sys tems self-organized into a hierarchical tree structure. \\r\\nRemote inter actions orchestrate a highly efficient process for decentralized collectiv e learning. This disruptive concept is realized by I-EPOS\, the Iterative Economic Planning and Optimized Selections\, accompanied by a paradigmatic software artifact. Strikingly\, I-EPOS outperforms related algorithms tha t involve non-local brute-force operations or exchange full information. T his paper contributes new experimental findings about the influence of n etwork topology and planning on learning efficiency as well as findings on techno-socio-economic trade-offs and global optimality. Experimental ev aluation with real-world data from energy and bike sharing pilots demonstr ates the grand potential of collective learning to design ethically and so cially responsible participatory sharing economies. X-ALT-DESC:\nAbstract:\nThe Internet of Things equips citizens with phenome nal new means for online participation in sharing economies. When agents s elf-determine options from which they choose\, for instance their resource consumption and production\, while these choices have a collective system -wide impact\, optimal decision-making turns into a combinatorial optimiza tion problem known as NP-hard. In such challenging computational problems\ , centrally managed (deep) learning systems often require personal data wi th implications on privacy and citizens’ autonomy. This paper envisions an alternative unsupervised and decentralized collective learning approach that preserves privacy\, autonomy and participation of multi-agent system s self-organized into a hierarchical tree structure. \nRemote interactions orchestrate a highly efficient process for decentralized collective learn ing. This disruptive concept is realized by I-EPOS\, the Iterative Economi c Planning and Optimized Selections\, accompanied by a paradigmatic softwa re artifact. Strikingly\, I-EPOS outperforms related algorithms that invol ve non-local brute-force operations or exchange full information. This pap er contributes new experimental \;findings about the influence of net work topology and planning on learning efficiency as well as \;findin gs on techno-socio-economic trade-offs and global optimality. Experimental evaluation with real-world data from energy and bike sharing pilots demon strates the grand potential of collective learning to design ethically and socially responsible participatory sharing economies.\n\n DTEND;TZID=Europe/Zurich:20181108T180000 END:VEVENT BEGIN:VEVENT UID:news319@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;TZID=Europe/Zurich:20181108T141500 SUMMARY:Number Theory Seminar: David Masser (Univ. of Basel) DESCRIPTION:Inspired by Schanuel's Conjecture\, Boris Zilber has proposed a ``Nullstellensatz'' (also conjectural) asserting which sorts of polynomia l-exponential equations in several variables have a complex solution. Last year Dale Brownawell and I published a proof in the situation which can b e regarded as ``typical''. But it does not cover all situations for two va riables\, some of which involve simply stated problems in one variable lik e finding complex $z \\neq 0$ with $e^z+e^{1/z}=1$. Recently Vincenzo Mant ova and I have settled the general case of two variables. We describe our methods -- for example\, to solve $$e^z+e^{\\root 9 \\of {1-z^9}}=1$$ one approach uses theta functions on ${\\bf C}^{28}$. X-ALT-DESC: Inspired by Schanuel's Conjecture\, Boris Zilber has proposed a ``Nullstellensatz'' (also conjectural) asserting which sorts of polynomia l-exponential equations in several variables have a complex solution. Last year Dale Brownawell and I published a proof in the situation which can b e regarded as ``typical''. But it does not cover all situations for two va riables\, some of which involve simply stated problems in one variable lik e finding complex $z \\neq 0$ with $e^z+e^{1/z}=1$. Recently Vincenzo Mant ova and I have settled the general case of two variables. We describe our methods -- for example\, to solve

$$e^z+e^{\\root 9 \\of {1-z^9}}=1$ $

one approach uses theta functions on ${\\bf C}^{28}$. DTEND;TZID=Europe/Zurich:20181108T151500 END:VEVENT BEGIN:VEVENT UID:news360@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175658 DTSTART;TZID=Europe/Zurich:20181108T121500 SUMMARY:Bernoullis Tafelrunde: Francesco Campagna DESCRIPTION:Abstract [t3://file?uid=1216]\, slides [t3://file?uid=1260] X-ALT-DESC:Abstract\, slides DTEND;TZID=Europe/Zurich:20181108T130000 END:VEVENT BEGIN:VEVENT UID:news352@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181103T092627 DTSTART;TZID=Europe/Zurich:20181107T110000 SUMMARY:Seminar in probability theory: Dominik Schröder (IST Austria) DESCRIPTION:For Wigner-type matrices\, i.e. Hermitian random matrices with independent\, not necessarily identically distributed entries above the diagonal\, we show that at any cusp singularity of the limiting eigenvalu e distribution the local eigenvalue statistics are universal and form a P earcey process. Since the density of states typically exhibits only squar e root or cubic root cusp singularities\, our work complements previous r esults on the bulk and edge universality and it thus completes the resolu tion of the Wigner-Dyson-Mehta universality conjecture for the last remai ning universality type. X-ALT-DESC: For Wigner-type matrices\, i.e. Hermitian random matrices with independent\, not necessarily identically distributed entries above the diagonal\, we show that at any cusp singularity of the limiting eigenvalu e distribution the local eigenvalue statistics are universal and form a P earcey process. Since the density of states typically exhibits only squar e root or cubic root cusp singularities\, our work complements previous r esults on the bulk and edge universality and it thus completes the resolu tion of the Wigner-Dyson-Mehta universality conjecture for the last remai ning universality type. END:VEVENT BEGIN:VEVENT UID:news358@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T174933 DTSTART;TZID=Europe/Zurich:20181106T121500 SUMMARY:Computer Science Colloquium: Dr. Tanja Christina Kaeser\, Stanford University DESCRIPTION:Abstract:\\r\\nLearning technologies are becoming increasingly important in today's education. This includes game-based learning and simu lations\, which produce high volume output\, and MOOCs (massive open onlin e courses)\, which reach a broad and diverse audience at scale. The users of such systems often are of very different backgrounds\, for example in t erms of age\, prior knowledge\, and learning speed. Adaptation to the spec ific needs of the individual user is therefore essential. In this talk\, I will present two of my contributions on modeling and predicting student l earning in computer-based environments with the goal to enable individuali zation. The first contribution introduces a new model and algorithm for re presenting and predicting student knowledge. The new approach is efficient and has been demonstrated to outperform previous work regarding predictio n accuracy. The second contribution introduces models\, which are able to not only take into account the accuracy of the user\, but also the inquiry strategies of the user\, improving prediction of future learning. Further more\, students can be clustered into groups with different strategies and targeted interventions can be designed based on these strategies. Finally \, I will also describe lines of future research. X-ALT-DESC:\nAbstract:\nLearning technologies are becoming increasingly imp ortant in today's education. This includes game-based learning and simulat ions\, which produce high volume output\, and MOOCs (massive open online c ourses)\, which reach a broad and diverse audience at scale. The users of such systems often are of very different backgrounds\, for example in term s of age\, prior knowledge\, and learning speed. Adaptation to the specifi c needs of the individual user is therefore essential. In this talk\, I wi ll present two of my contributions on modeling and predicting student lear ning in computer-based environments with the goal to enable individualizat ion. The first contribution introduces a new model and algorithm for repre senting and predicting student knowledge. The new approach is efficient an d has been demonstrated to outperform previous work regarding prediction a ccuracy. The second contribution introduces models\, which are able to not only take into account the accuracy of the user\, but also the inquiry st rategies of the user\, improving prediction of future learning. Furthermor e\, students can be clustered into groups with different strategies and ta rgeted interventions can be designed based on these strategies. Finally\, I will also describe lines of future research. DTEND;TZID=Europe/Zurich:20181106T133000 END:VEVENT BEGIN:VEVENT UID:news340@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T082628 DTSTART;TZID=Europe/Zurich:20181106T103000 SUMMARY:Seminar Algebra and Geometry: Juliette Bavard (University of Rennes ) DESCRIPTION:The plane minus a Cantor set and its mapping class group appear in many dynamical contexts\, including group actions on surfaces\, the study of groups of homeomorphisms on a Cantor set\, and complex dynamics. In this talk\, I will motivate the study of this 'big mapping class grou ps'. I will then present the 'ray graph'\, which is a Gromov-hyperbolic graph on which this group acts by isometries. X-ALT-DESC:The plane minus a Cantor set and its mapping class group appear in many dynamical contexts\, including \;group \;actions on surfac es\, the study of groups of homeomorphisms on a Cantor set\, and complex d ynamics. \;In this talk\, I will motivate the study of this 'big mappi ng class groups'. I will then present the 'ray \;graph'\, which is a G romov-hyperbolic \;graph \;on which this \;group \;acts by isometries. \; \;

DTEND;TZID=Europe/Zurich:20181106T120000 END:VEVENT BEGIN:VEVENT UID:news350@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181023T144703 DTSTART;TZID=Europe/Zurich:20181102T110000 SUMMARY:Seminar in Numerical Analysis: Maryna Kachanovska (ENSTA ParisTech) DESCRIPTION:In this work we consider the problem of the sound propagation in a bronchial network. Asymptotically\, this phenomenon can be modelled by a weighted wave equation posed on a fractal (i.e. self-similar) 1D tre e. The principal difficulty for the numerical resolution of the problem is the 'infiniteness' of the geometry. To deal with this issue\, we will present transparent boundary conditions\, used to truncate the computati onal domain to a finite subtree.\\r\\nThe construction of such transpare nt conditions relies on the approximation of the Dirichlet-to-Neumann (Dt N) operator\, whose symbol is a meromorphic function that satisfies a ce rtain non-linear functional equation. We present two approaches to approx imate the DtN in the time domain\, alternative to the low-order absorbing boundary conditions\, which appear inefficient in this case.\\r\\n The f irst approach stems from the use of the convolution quadrature (cf. [Lubi ch 1988]\, [Banjai\, Lubich\, Sayas 2016])\, which consists in constructi ng an exact DtN for a semi-discretized in time problem. In this case the combination of the explicit leapfrog method for the volumic terms and the implicit trapezoid rule for the boundary terms leads to a second-order s cheme stable under the classical CFL condition.\\r\\nThe second approach is motivated by the Engquist-Majda ABCs (cf. [Engquist\, Majda 1977])\, a nd consists in approximating the DtN by local operators\, obtained from th e truncation of the meromorphic series which represents the symbol of the DtN. We show how the respective error can be controlled and provide some complexity estimates.\\r\\nThis is a joint work with Patrick Joly (INRIA \, France) and Adrien Semin (TU Darmstadt\, Germany). \\r\\nFor further in formation about the seminar\, please visit this webpage. X-ALT-DESC: In this work we consider the problem of the sound propagation in a bronchial network. Asymptotically\, this phenomenon can be modelled by a weighted wave equation posed on a fractal (i.e. self-similar) 1D tre e. The principal difficulty for the numerical resolution of the problem is the 'infiniteness' of the geometry. To deal with this issue\, we will present transparent boundary conditions\, used to truncate the computati onal domain to a finite subtree.\nThe construction of such transparent c onditions relies on the approximation of the Dirichlet-to-Neumann (DtN) o perator\, whose symbol is a meromorphic function that satisfies a certai n non-linear functional equation. We present two approaches to approximat e the DtN in the time domain\, alternative to the low-order absorbing bou ndary conditions\, which appear inefficient in this case.\n The first app roach stems from the use of the convolution quadrature (cf. [Lubich 1988] \, [Banjai\, Lubich\, Sayas 2016])\, which consists in constructing an ex act DtN for a semi-discretized in time problem. In this case the combinat ion of the explicit leapfrog method for the volumic terms and the implici t trapezoid rule for the boundary terms leads to a second-order scheme st able under the classical CFL condition.\nThe second approach is motivated by the Engquist-Majda ABCs (cf. [Engquist\, Majda 1977])\, and consists in approximating the DtN by local operators\, obtained from the truncation of the meromorphic series which represents the symbol of the DtN. We sho w how the respective error can be controlled and provide some complexity estimates.\nThis is a joint work with Patrick Joly (INRIA\, France) and A drien Semin (TU Darmstadt\, Germany). \nFor further information about the seminar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20181102T120000 END:VEVENT BEGIN:VEVENT UID:news318@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;TZID=Europe/Zurich:20181101T141500 SUMMARY:Number Theory Seminar: Shabnam Akhtari (Univ. of Oregon / MPIM Bonn ) DTEND;TZID=Europe/Zurich:20181101T151500 END:VEVENT BEGIN:VEVENT UID:news351@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175709 DTSTART;TZID=Europe/Zurich:20181101T121500 SUMMARY:Bernoullis Tafelrunde: Séverin Philip DESCRIPTION:Abstract [t3://file?uid=1178] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20181101T130000 END:VEVENT BEGIN:VEVENT UID:news327@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181030T093900 DTSTART;TZID=Europe/Zurich:20181031T110000 SUMMARY:Seminar in probability theory: Anton Klimovsky (Duisburg-Essen) DESCRIPTION:Finding the (space-height) distribution of the (local) extrema of high-dimensional strongly correlated random fields is a notorious hard problem with many applications. Following Fyodorov & Sommers (2007)\, we f ocus on the Gaussian fields with isotropic increments and take the viewpoi nt of statistical physics. By exploiting various probabilistic symmetries\ , we rigorously derive the Fyodorov-Sommers formula for the log-partition function in the high-dimensional limit. The formula suggests a rich pictur e for the distribution of the local extrema akin to the celebrated spheric al Sherrington-Kirkpatrick model with mixed p-spin interactions. X-ALT-DESC: Finding the (space-height) distribution of the (local) extrema of high-dimensional strongly correlated random fields is a notorious hard problem with many applications. Following Fyodorov &\; Sommers (2007)\, we focus on the Gaussian fields with isotropic increments and take the vi ewpoint of statistical physics. By exploiting various probabilistic symmet ries\, we rigorously derive the Fyodorov-Sommers formula for the log-parti tion function in the high-dimensional limit. The formula suggests a rich p icture for the distribution of the local extrema akin to the celebrated sp herical Sherrington-Kirkpatrick model with mixed p-spin interactions. END:VEVENT BEGIN:VEVENT UID:news303@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T173852 DTSTART;TZID=Europe/Zurich:20181025T161500 SUMMARY:Perlen-Kolloquium: Dr. Jitao David Zhang (F. Hoffmann-La Roche AG\, Basel) DESCRIPTION:Mathematics is integral to the interdisciplinary research that drives modern drug discovery. The talk will walk the audience through basi c principles and selected applications of computational biology and bioinf ormatics\, a branch of applied mathematics\, in drug discovery\, It is hop ed that the principles\, examples\, and unsolved challenges discussed duri ng the talk can initiate an exchange between researchers from different fi elds\, and inspire future interdisciplinary efforts in disease understandi ng and drug discovery.\\r\\nJitao David Zhang was a Marie-Curie Fellow at European Bioinformatics Institute (2007-2008) and an International PhD Pro gramm Fellow at German Cancer Research Center (2008-2011). He obtained the doctorate degree in computational biology and biostatistics in 2011 and i n that year joined Pharma Research and Early Development (pRED)\, the rese arch unit of F. Hoffmann-La Roche AG in Basel\, Switzerland. He supports e arly drug-discovery projects\, develops algorithms and software for data a nalysis and interpretation\, and collaborates to devise new technologies a nd platforms. His research interests include biological data modelling and integration\, biological network analysis\, molecular phenotyping\, and a pplied machine learning in disease understanding and preclinical drug disc overy.\\r\\nSlides [t3://file?uid=1194] X-ALT-DESC:Mathematics is integral to the interdisciplinary research that d rives modern drug discovery. The talk will walk the audience through basic principles and selected applications of computational biology and bioinfo rmatics\, a branch of applied mathematics\, in drug discovery\, It is hope d that the principles\, examples\, and unsolved challenges discussed durin g the talk can initiate an exchange between researchers from different fie lds\, and inspire future interdisciplinary efforts in disease understandin g and drug discovery.\nJitao David Zhang was a Marie-Curie Fellow at Europ ean Bioinformatics Institute (2007-2008) and an International PhD Programm Fellow at German Cancer Research Center (2008-2011). He obtained the doct orate degree in computational biology and biostatistics in 2011 and in tha t year joined Pharma Research and Early Development (pRED)\, the research unit of F. Hoffmann-La Roche AG in Basel\, Switzerland. He supports early drug-discovery projects\, develops algorithms and software for data analys is and interpretation\, and collaborates to devise new technologies and pl atforms. His research interests include biological data modelling and inte gration\, biological network analysis\, molecular phenotyping\, and applie d machine learning in disease understanding and preclinical drug discovery .\nSlides END:VEVENT BEGIN:VEVENT UID:news344@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181012T175433 DTSTART;TZID=Europe/Zurich:20181019T110000 SUMMARY:Seminar in Numerical Analysis: Martin Rumpf (Universität Bonn) DESCRIPTION:We investigate a generalization of cubic splines to Riemannian manifolds. Spline curves are defined as minimizers of the spline energy - a combination of the Riemannian path energy and the time integral of the s quared covariant derivative of the path velocity - under suitable interpol ation conditions. A variational time discretization for the spline energy leads to a constrained optimization problem over discrete paths on the man ifold. Existence of continuous and discrete spline curves is established u sing the direct method in the calculus of variations. Furthermore\, the co nvergence of discrete spline paths to a continuous spline curve follows fr om the Γ-convergence of the discrete to the continuous spline energy. Fin ally\, selected example settings are discussed\, including splines on embe dded finite-dimensional manifolds\, on a high-dimensional manifold of disc rete shells with applications in surface processing\, and on the infinite- dimensional shape manifold of viscous rods. This is based on joint work wi th Behrend Heeren and Benedikt Wirth.\\r\\nFor further information about t he seminar\, please visit this webpage. X-ALT-DESC:We investigate a generalization of cubic splines to Riemannian m anifolds. Spline curves are defined as minimizers of the spline energy - a combination of the Riemannian path energy and the time integral of the sq uared covariant derivative of the path velocity - under suitable interpola tion conditions. A variational time discretization for the spline energy l eads to a constrained optimization problem over discrete paths on the mani fold. Existence of continuous and discrete spline curves is established us ing the direct method in the calculus of variations. Furthermore\, the con vergence of discrete spline paths to a continuous spline curve follows fro m the Γ-convergence of the discrete to the continuous spline energy. Fina lly\, selected example settings are discussed\, including splines on embed ded finite-dimensional manifolds\, on a high-dimensional manifold of discr ete shells with applications in surface processing\, and on the infinite-d imensional shape manifold of viscous rods. This is based on joint work wit h Behrend Heeren and Benedikt Wirth.\nFor further information about the se minar\, please visit this webpage. DTEND;TZID=Europe/Zurich:20181019T120000 END:VEVENT BEGIN:VEVENT UID:news207@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T163917 DTSTART;TZID=Europe/Zurich:20181018T190000 SUMMARY:Kickoff AlumniComputerScience DESCRIPTION:Die AlumniComputerScience werden im Anschluss an das DMI-Kolloq uium mit einem Apéro eröffnet. Sie sind herzlich dazu eingeladen. X-ALT-DESC:Die AlumniComputerScience werden im Anschluss an das DMI-Kolloqu ium mit einem Apéro eröffnet. Sie sind herzlich dazu eingeladen. END:VEVENT BEGIN:VEVENT UID:news201@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T163902 DTSTART;TZID=Europe/Zurich:20181018T171500 SUMMARY:DMI-Kolloquium: Prof. Dr. Jiří Černý und Prof. Dr. Julia Vogt ( Universität Basel) DESCRIPTION:Prof. Dr. Jiří Černý\, Professor für Wahrscheinlichkeitsth eorieRandom Walk Percolation and Level Sets of Random Fields\\r\\nProf. Dr . Julia Vogt\, Professorin für Adaptive Systems and Medical Data ScienceM achine Learning for Clinical Data Analysis and Precision Medicine\\r\\n\\r \\nIm Anschluss an die Vorträge findet das Kickoff der Alumni Computer Sc ience statt und es wird ein Apéro offeriert. Der Anlass ist öffentlich.\ \r\\nFlyer [t3://file?uid=1009] X-ALT-DESC:\nProf. Dr. Jiří Černý\, Professor für Wahrscheinlichkeitst heorie

\\begin{equation}\\label{eq}

\\fr ac{x^m-1}{x-1} = \\frac{y^n-1}{y-1}\, \\\; \\\; y>\;x>\;1\, \\\; m > \; n >\; 2.

\\end{equation}

There are two known solutions $(x \, y\,m\, n)=(2\, 5\, 5\, 3)\, (2\, 90\, 13\, 3)$ and it is believed that these are the only solutions. It is not known if this equation has finitel y or infinitely many solutions\, and not even if that is the case if we fi x one of the variables. It is known that there are finitely many solutions if we fix any two variables. Moreover\, there are effective results in al l cases\, except when the two fixed variables are the exponents $m$ and $n $. If the fixed $m$ and $n$ additionally satisfy \; $\\gcd(m-1\, n-1)& gt\;1$\, then there is an effective finiteness result. My co-authors and m e showed that if $n \\geq 3$ is a fixed integer\, then there exists an eff ectively computable constant $c (n)$ such that $\\max \\{ x\, y\, m \\} &l t\; c (n)$ for all $x\, y$ and $m$ that satisfy Goormaghtigh's equation wi th $\\gcd(m-1\,n-1)>\;1$. \; In case $n \\in \\{ 3\, 4\, 5 \\}$\, we solved the equation completely\, subject to this non-coprimality conditio n. DTEND;TZID=Europe/Zurich:20181004T151500 END:VEVENT BEGIN:VEVENT UID:news324@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T082628 DTSTART;TZID=Europe/Zurich:20181002T103000 SUMMARY:Seminar Algebra and Geometry: Immanuel van Santen\, Anne Lonjou and Jeremy Blanc (University of Basel) DESCRIPTION:Immanuel van Santen will speak about „Embeddings and tame aut omorphisms in affine geometry"\, \\r\\nAnne Lonjou will explain some link between "Cremona group and geometric group theory"\, and \\r\\nJérémy Blanc will present us "Birational geometry of surfaces and threefolds". X-ALT-DESC:\nImmanuel van Santen will speak about „Embeddings and tame au tomorphisms in affine geometry"\;\, \;\nAnne Lonjou will explain s ome link between "\;Cremona group and geometric group theory"\;\, and \;\nJérémy Blanc will present us "\;Birational geometry of s urfaces and threefolds"\;. DTEND;TZID=Europe/Zurich:20181002T120000 END:VEVENT BEGIN:VEVENT UID:news305@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175030 DTSTART;TZID=Europe/Zurich:20180928T121500 SUMMARY:Computer Science Colloquium: Prof. Schöffmann DESCRIPTION:Abstract:In hospitals all around the world\, medical multimedia information systems have gained high importance over the last few years. One of the reasons is that an increasing number of interventions is perfor med in a minimally invasive way. These endoscopic inspections and surgerie s are conducted with a tiny camera – the endoscope – which enables cli nicians to control the intervention via an external display. Apart from th e viewing purpose\, the video signal can also be recorded and used for pos t-procedural scenarios\, such as communicating operation techniques (i.e.\ , training and teaching)\, planning future interventions\, and medical for ensics and analytics. The problem\, however\, is the sheer amount of unstr uctured video data that is added to the multimedia archive on a daily basi s. Without proper management and content analytics the videos cannot be us ed efficiently by clinicians. In this talk I will summarize our recent inv estigations in this challenging research field and conclude on the achieve d results. \\r\\nBio:Dr. Klaus Schöffmann is an Associate Professor in th e Distributed Multimedia Systems research group at the Institute of Inform ation Technology (ITEC) at Klagenfurt University\, Austria. He received hi s PhD in 2009 and his habilitation (venia docendi) in 2015\, both in compu ter science and from Klagenfurt University. His research focuses on video analytics and interactive multimedia systems\, particularly in the medical domain. He has co-authored more than 100 publications on various topics i n multimedia\, inclusive of more than 25 on different aspects of medical m ultimedia systems. He has co-organized several international conferences\, workshops\, and special sessions in the field of multimedia. Furthermore\ , he is co-founder of the Video Browser Showdown (VBS) – an internationa l live evaluation competition of interactive video search. He is a member of the IEEE and the ACM\, and a regular reviewer for international confere nces and journals in the field of multimedia. Klaus Schöffmann teaches va rious courses in computer science\, including mobile app development\, vid eo retrieval\, distributed multimedia systems\, and operating systems. X-ALT-DESC:\n

I will describe how the Riemann Zeta function on t he critical line can be viewed as a pseudo-random Gaussian field with a co rrelation function with logarithmic growth. Such log-correlated random fie lds have recently attracted considerable interest in probability theory. F yodorv\, Hiary and Keating conjectured several striking results about the extreme values of the Riemann Zeta function based on this connection. In t his talk I will explain how a certain approximate tree structure in Dirich let polynomials can be used to prove one of their conjectures\, giving the asymptotics of the maximum of the magnitude of the function in a typical interval of length O(1).X-ALT-DESC: <\;pre wrap="\;"\;>\;I will describe how the Rieman n Zeta function on the critical line can be viewed as a pseudo-random Gaus sian field with a correlation function with logarithmic growth. Such log-c orrelated random fields have recently attracted considerable interest in p robability theory. Fyodorv\, Hiary and Keating conjectured several strikin g results about the extreme values of the Riemann Zeta function based on t his connection. In this talk I will explain how a certain approximate tree structure in Dirichlet polynomials can be used to prove one of their conj ectures\, giving the asymptotics of the maximum of the magnitude of the fu nction in a typical interval of length O(1).<\;/pre>\; DTEND;TZID=Europe/Zurich:20180927T151500 END:VEVENT BEGIN:VEVENT UID:news312@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175727 DTSTART;TZID=Europe/Zurich:20180927T121500 SUMMARY:Bernoullis Tafelrunde: Philipp Mekler DESCRIPTION:Abstract [t3://file?uid=1008] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20180927T130000 END:VEVENT BEGIN:VEVENT UID:news322@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181204T082628 DTSTART;TZID=Europe/Zurich:20180925T103000 SUMMARY:Seminar Algebra and Geometry: Julia Schneider\, Egor Yasinsky and P hilipp Mekler (University of Basel) DESCRIPTION:Julia will speak about "A_k-singularities of plane curves of fi xed bidegree".\\r\\nEgor will answer to "What transformation groups in alg ebraic\, differential and metric geometry have in common?". \\r\\nPhilipp will speak about "Algebraic Statistics: Gaussian Mixtures and Beyond". X-ALT-DESC:\nJulia will speak about "\;A_k-singularities of plane curve s of fixed bidegree"\;.\nEgor will answer to "\;What transformatio n groups in algebraic\, differential and metric geometry have in common?&q uot\;. \;\nPhilipp will speak about "\;Algebraic Statistics: Gauss ian Mixtures and Beyond"\;. DTEND;TZID=Europe/Zurich:20180925T120000 END:VEVENT BEGIN:VEVENT UID:news197@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T164044 DTSTART;VALUE=DATE:20180920 SUMMARY:Doktoratskolloquium Mathematik: Mattias Hemmig END:VEVENT BEGIN:VEVENT UID:news315@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175739 DTSTART;TZID=Europe/Zurich:20180920T121500 SUMMARY:Bernoullis Tafelrunde: Anna Karpova DESCRIPTION:Abstract [t3://file?uid=1020]\, slides [t3://file?uid=1044] X-ALT-DESC: Abstract\, slides DTEND;TZID=Europe/Zurich:20180920T130000 END:VEVENT BEGIN:VEVENT UID:news325@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180925T212513 DTSTART;TZID=Europe/Zurich:20180906T110000 SUMMARY:Seminar in probability theory: Lisa Hartung (New York University) DESCRIPTION:It was proven by Rider and Virag that the logarithm of the char acteristic polynomial of the Ginibre ensemble converges to a logarithmical ly correlated random field. In this talk we will see how this connection c an be established on the level if powers of the characteristic polynomial by proving convergence to Gaussian multiplicative chaos. We consider the r ange of powers in the L^2 phase. \\r\\n(Joint work in progress with Paul B ourgade and Guillaume Dubach). X-ALT-DESC: It was proven by Rider and Virag that the logarithm of the char acteristic polynomial of the Ginibre ensemble converges to a logarithmical ly correlated random field. In this talk we will see how this connection c an be established on the level if powers of the characteristic polynomial by proving convergence to Gaussian multiplicative chaos. We consider the r ange of powers in the L^2 phase. \n(Joint work in progress with Paul Bourg ade and Guillaume Dubach). DTEND;TZID=Europe/Zurich:20180906T120000 END:VEVENT BEGIN:VEVENT UID:news306@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180927T122021 DTSTART;TZID=Europe/Zurich:20180822T110000 SUMMARY:Seminar in probability theory: Alexander Drewitz (Köln) DESCRIPTION:We consider two fundamental percolation models with long-range correlations: The Gaussian free field and (the vacant set) of Random Inter lacements. Both models have been the subject of intensive research during the last years and decades\, on Zd as well as on some more general graphs. We investigate some structural percolative properties around their critic al parameters\, in particular the ubiquity of the infinite components of c omplementary phases. \\r\\nThis talk is based on joint works with A. Prév ost (Köln) and P.-F. Rodriguez (Bures-sur-Yvette). X-ALT-DESC: We consider two fundamental percolation models with long-range correlations: The Gaussian free field and (the vacant set) of Random Inter lacements. Both models have been the subject of intensive research during the last years and decades\, on Zd as well as on some more general graphs. We investigate some structural percolative properties around their critic al parameters\, in particular the ubiquity of the infinite components of c omplementary phases. \nThis talk is based on joint works with A. Prévost (Köln) and P.-F. Rodriguez (Bures-sur-Yvette). DTEND;TZID=Europe/Zurich:20180822T120000 END:VEVENT BEGIN:VEVENT UID:news209@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20211104T143247 DTSTART;VALUE=DATE:20180713 SUMMARY:Donau–Rhein Modelltheorie und Anwendungen\, 3rd meeting DESCRIPTION:Link to schedule. [https://sites.google.com/site/drmta3/] X-ALT-DESC:Link to sch edule. \; END:VEVENT BEGIN:VEVENT UID:news204@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175129 DTSTART;VALUE=DATE:20180703 SUMMARY:Public lecture on “Massive-Scale Analytics Applied to Real-World Problems” by Prof. David A. Bader (Georgia Institute of Technology\, US) DESCRIPTION:This public lecture is an outreach opportunity on behalf of the PASC18 conference and the University of Basel to inform the general publi c about the societal challenges we solve through research and innovation i n and around advanced scientific computing. Details of the lecture open to the general public (free of charge) Emerging real-world graph problems in clude: detecting and preventing disease in human populations\; revealing c ommunity structure in large social networks\; and improving the resilience of the electric power grid. Unlike traditional applications in computatio nal science and engineering\, solving these social problems at scale often raises new challenges because of the sparsity and lack of locality in the data\, the need for research on scalable algorithms and development of fr ameworks for solving these real-world problems on high performance compute rs\, and for improved models that capture the noise and bias inherent in t he torrential data streams. In this talk\, Bader will discuss the opportun ities and challenges in massive data-intensive computing for applications in social sciences\, physical sciences\, and engineering.Biography of the speakerDavid Bader is Professor and Chair of the School of Computational S cience and Engineering at Georgia Institute of Technology\, and is regarde d as one of the world’s leading experts in data sciences. His interests are at the intersection of high performance computing (HPC) and real-world applications\, including cybersecurity\, massive-scale analytics\, and co mputational genomics. Bader has co-authored over 200 articles in peer-revi ewed journals and conferences\, and is an associate editor for high-impact publications including IEEE Transactions on Computers\, ACM Transactions on Parallel Computing\, and ACM Journal of Experimental Algorithmics. He i s a Fellow of the IEEE and AAAS\, and has served on a number of advisory c ommittees in scientific computing and cyber-infrastructure\, including the White House's National Strategic Computing Initiative. Bader has served a s a lead scientist in several DARPA programs and is a co-founder of the Gr aph500 list\, a rating of "Big Data" computing platforms. He was recognize d as a “Rock Star of HPC” by InsideHPC and as HPCwire's “People to W atch” in 2012 and 2014.More details: pasc18.pasc-conference.org/program/ public-lecture/ [https://pasc18.pasc-conference.org/program/public-lecture /] X-ALT-DESC:This public lecture is an outreach opportunity on behalf of the PASC18 conference and the University of Basel to inform the general public about the societal challenges we solve through research and innovation in and around advanced scientific computing.

Emerging real -world graph problems include: detecting and preventing disease in human p opulations\; revealing community structure in large social networks\; and improving the resilience of the electric power grid. Unlike traditional ap plications in computational science and engineering\, solving these social problems at scale often raises new challenges because of the sparsity and lack of locality in the data\, the need for research on scalable algorith ms and development of frameworks for solving these real-world problems on high performance computers\, and for improved models that capture the nois e and bias inherent in the torrential data streams. In this talk\, Bader w ill discuss the opportunities and challenges in massive data-intensive com puting for applications in social sciences\, physical sciences\, and engin eering.

David Bader is Pro fessor and Chair of the School of Computational Science and Engineering at Georgia Institute of Technology\, and is regarded as one of the world’s leading experts in data sciences. His interests are at the intersection o f high performance computing (HPC) and real-world applications\, including cybersecurity\, massive-scale analytics\, and computational genomics. Bad er has co-authored over 200 articles in peer-reviewed journals and confere nces\, and is an associate editor for high-impact publications including I EEE Transactions on Computers\, ACM Transactions on Parallel Computing\, a nd ACM Journal of Experimental Algorithmics. He is a Fellow of the IEEE an d AAAS\, and has served on a number of advisory committees in scientific c omputing and cyber-infrastructure\, including the White House's National S trategic Computing Initiative. Bader has served as a lead scientist in sev eral DARPA programs and is a co-founder of the Graph500 list\, a rating of "\;Big Data"\; computing platforms. He was recognized as a “Roc k Star of HPC” by InsideHPC and as HPCwire's “People to Watch” in 20 12 and 2014.

More details:

pasc18.pasc-conference.org/pro gram/public-lecture/

DTEND;VALUE=DATE:20180703 END:VEVENT BEGIN:VEVENT UID:news203@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175410 DTSTART;VALUE=DATE:20180702 SUMMARY:PASC18: Scientific computing at its best through “Fast and Big Da ta\, Fast and Big Computation” DESCRIPTION:The PASC (Platform for Advancing Scientific Computing) Conferen ce is an international platform for the exchange of competences in scienti fic computing and computational science\, with a strong focus on methods\, tools\, algorithms\, application challenges\, and novel techniques and us age of high performance computing. PASC18 (pasc18.pasc-conference.org [htt ps://pasc18.pasc-conference.org]) is the fifth edition of the conference s eries\, and will be held in Basel\, Switzerland\, from July 2 (9:00 a.m.) to 4 (6:00 p.m.)\, 2018 at the Congress Center. It is expected to bring to gether over 400 experts in scientific computing from all over the world. P ASC18 is co-sponsored by the Association for Computing Machinery (ACM) and the Swiss National Supercomputing Centre (CSCS). The PASC18 theme is “F ast and Big Data\, Fast and Big Computation.” “Large computations cons ume and generate massive amounts of data\, and processing of big data requ ires large amounts of computational power\, which increasingly depends on parallel computation\,” explain Florina Ciorba and Erik Lindahl\, the PA SC18 Co-Chairs. “The PASC18 theme emphasizes our vision of the close cou pling of data and computation. Exposing and expressing massive and irregul ar parallelism in computational problems are key challenges for exploiting the massive and heterogeneous parallelism available in current and expect ed in future HPC systems\, as well as to find new ways of generating scien tific insight from data and models. Through its rich\, diverse\, and inter active program\, PASC18 will highlight the computational approaches that c omputational scientists\, computer scientists\, and practitioners employ t oday and will employ over the next decades to address these challenges.” The PASC18 technical program (pasc18.pasc-conference.org/program/schedule / [https://pasc18.pasc-conference.org/program/schedule/]) is organized aro und eight scientific domains: Chemistry and Materials\, Climate and Weathe r\, Computer Science and Applied Mathematics\, Emerging Domains in HPC\, E ngineering\, Life Sciences\, Physics\, and Solid Earth Dynamics. Over the course of three full days\, the program includes\, technical sessions with keynotes\, panels\, minisymposia\, peer-reviewed papers and poster sessio ns. Full papers are published in the ACM Digital Library. We look forward to advancing scientific computing with you at the Basel Congress Center on July 2-4! X-ALT-DESC: The

The PASC18 theme is

The PASC18 technical program (pasc18.pasc-conference.org/program/schedule/ ) is organized around eight scientific domains: Chemistry and Materials\, Climate and Weather\, Computer Science and Applied Mathematics\, Emerging Domains in HPC\, Engineering\, Life Sciences\, Physics\, and Solid Earth D ynamics. Over the course of three full days\, the program includes\, techn ical sessions with keynotes\, panels\, minisymposia\, peer-reviewed papers and poster sessions. Full papers are published in the ACM Digital Library .

We look forward to advancing scientific computing with you a t the Basel Congress Center on July 2-4!

DTEND;VALUE=DATE:20180704 END:VEVENT BEGIN:VEVENT UID:news200@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T101415 DTSTART;TZID=Europe/Zurich:20180621T161500 SUMMARY:Doktoratskolloquium Mathematik: Linda Frey END:VEVENT BEGIN:VEVENT UID:news202@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175225 DTSTART;TZID=Europe/Zurich:20180621T100000 SUMMARY:Computer Science Colloquium: Prof. Allen D. Malony DESCRIPTION:Abstract: Since the beginning of ``high-performance'' parallel computing\, observingand analyzing performance for purposes of finding bot tlenecks andidentifying opportunities for improvement has been at the hear t ofdelivering the performance potential of next-generation scalable syste ms.Interestingly\, it is the ever-changing parallel computing landscape th at isthe main driver of requirements for parallel performance technology a nd theimprovements necessary beyond the current state-of-the-art. Indeed \, thedevelopment and application of our TAU Performance System over many yearslargely follows an evolutionary path of addressing measurement and an alysisproblems in new parallel machines and programming environments.Howev er\, the outlook to future parallel systems with high degrees ofconcurrenc y\, heterogeneous components\, dynamic runtime environments\,asynchronous execution\, and power constraints suggests a new perspectivewill be needed on the role of performance observation and analysis inrespect to tool tec hnology integration and performance optimizationmethods. The reliance on post-mortem analysis of application-level("1st person") performance measu rements is prohibitive forexascale-class machines because of the performan ce data volume\, theprimitive basis for performance data attribution\, and the fundamentalproblem of performance variation that will exist. Instea d\, it will beimportant to provide introspection support across the exasca le softwarestack to understand how system ("3rd person") resources are use d duringexecution. Furthermore\, the opportunity to couple a global perf ormanceintrospection capability (a "performance backplane") with onlineper formance decision analytics inspires the concept of an autonomicperformanc e system that can feed back policy-based decisions to guidethe computation to better states of execution.The talk will explore these issues by givin g a brief retrospective onperformance tool evolution\, setting the stage f or current researchprojects where a new performance perspective is being p ursued. It willalso speculate on what might be included in next-generati on parallelsystems hardware\, specifically to make the exascale machines m oreperformance-aware and dynamically-adaptive. Speaker Bio: Allen D. Malon y is a Professor in the Department of Computer andInformation Science at t he University of Oregon (UO) where he directsparallel computing research p rojects\, notably the TAU parallelperformance system project. He has ext ensive experience in performancebenchmarking and characterization of high- performance computing systems\,and has developed performance evaluation to ols for a range of parallelmachines during the last 30 years. Malony is also interested incomputational and data science. He is the Director of the new OregonAdvanced Computing Institute for Science and Society (OACISS ) at UO.Malony was awarded the NSF National Young Investigator award\, was aFulbright Research Scholar to The Netherlands and Austria\, and received the Alexander von Humboldt Research Award for Senior U.S. Scientists bythe Alexander von Humboldt Foundation. Last year he was theFulbright-Tocque ville Distinguished Chair to France. Recently\, he wasaward the Fulbrigh t for the Future by the Franco-Americaine FulbrightCommission. Malony is the CEO of ParaTools\, Inc.\, which he founded withDr. Sameer Shende in 2 004. ParaTools SAS is a French company theystarted in 2014\, and is whol ly-owned company by ParaTools\, Inc.ParaTools specializes in performance a nalysis and engineering\, HPCapplications and optimization\, and parallel software\, hardware\, andtools. X-ALT-DESC:\n

and analyzing performance for purposes of finding bottlenecks and

identifying opportunities for improvement has been at the heart of

delivering the performance potential of next -generation scalable systems.

Interestingly\, it is the ever-changing parallel computing landscape that is

the main driver of requirements for parallel performance technology and the

improvements necessary b eyond the current state-of-the-art. \; Indeed\, the

development a nd application of our TAU Performance System over many years

largely follows an evolutionary path of addressing measurement and analysis

p roblems in new parallel machines and programming environments.

However\, the outlook to future parallel systems with high degrees of

concurrency\, heterogeneous components\, dynamic runtime environments\,

will be needed on the role of performance observation and analysi s in

respect to tool technology integration and performance optimizat ion

methods. \; The reliance on post-mortem analysis of applicati on-level

("\;1st person"\;) performance measurements is prohi bitive for

exascale-class machines because of the performance data vo lume\, the

primitive basis for performance data attribution\, and the fundamental

problem of performance variation that will exist. \; Instead\, it will be

important to provide introspection support acro ss the exascale software

stack to understand how system ("\;3rd p erson"\;) resources are used during

execution. \; Furthermore \, the opportunity to couple a global performance

introspection capab ility (a "\;performance backplane"\;) with online

performance decision analytics inspires the concept of an autonomic

performance system that can feed back policy-based decisions to guide

the computa tion to better states of execution.

The talk will explore these issues by giving a brief retrospective on

performance tool evolution \, setting the stage for current research

projects where a new perfor mance perspective is being pursued. \; It will

also speculate on what might be included in next-generation parallel

systems hardware\, specifically to make the exascale machines more

performance-aware an d dynamically-adaptive.

Information Science at the University of Oregon (UO) where he directs

parallel computing re search projects\, notably the TAU parallel

performance system project . \; He has extensive experience in performance

benchmarking and characterization of high-performance computing systems\,

and has deve loped performance evaluation tools for a range of parallel

machines d uring the last 30 years. \; Malony is also interested in

computat ional and data science. \; He is the Director of the new Oregon

A dvanced Computing Institute for Science and Society (OACISS) at UO.

M alony was awarded the NSF National Young Investigator award\, was a

F ulbright Research Scholar to The Netherlands and Austria\, and received

the Alexander von Humboldt Research Award for Senior U.S. Scientists by

the Alexander von Humboldt Foundation. \; Last year he was the

award the Fulbright for the Future by the Franco-Americaine F ulbright

Commission. \; Malony is the CEO of ParaTools\, Inc.\, w hich he founded with

Dr. Sameer Shende in 2004. \; ParaTools SAS is a French company they

started in 2014\, and is wholly-owned compan y by ParaTools\, Inc.

ParaTools specializes in performance analysis a nd engineering\, HPC

applications and optimization\, and parallel sof tware\, hardware\, and

tools.

DTEND;TZID=Europe/Zurich:20180621T120000 END:VEVENT BEGIN:VEVENT UID:news196@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T174105 DTSTART;TZID=Europe/Zurich:20180601T173000 SUMMARY:Perlen-Kolloquium: Maryna Viazovska (EPFL) DESCRIPTION:In this talk we will speak about packing problems in multidimen sional spaces. We will give an overview of this interesting class of mathe matical questions and recent progress in the area. Also we will explain the importance of good packing configurations in applications such as inte rnet\, telecommunication\, and data storage.\\r\\nThe talk is part of the annual meeting 2018 of the Swiss Mathematical Society. X-ALT-DESC:\nIn this talk we will speak about packing problems in multidime nsional spaces. We will give an overview of this interesting class of math ematical questions and recent progress in the area. \; Also we will ex plain the importance of good packing configurations in applications such a s internet\, telecommunication\, and data storage.\nThe talk is part of th e annual meeting 2018 of the Swiss Mathematical Society. DTEND;TZID=Europe/Zurich:20180601T183000 END:VEVENT BEGIN:VEVENT UID:news87@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T174204 DTSTART;VALUE=DATE:20180601 SUMMARY:Number Theory Days 2018 DESCRIPTION:Link to website [https://numbertheory.dmi.unibas.ch/NTD2018] X-ALT-DESC:Link t o website DTEND;VALUE=DATE:20180602 END:VEVENT BEGIN:VEVENT UID:news223@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T181333 DTSTART;TZID=Europe/Zurich:20180601T110000 SUMMARY:Seminar in Numerical Analysis: Kenneth Duru (Ludwig-Maximilians-Uni versität München) DESCRIPTION:High order accurate and explicit time-stable solvers are well s uited for hyperbolic wave propagation problems. However\, because of the complexities of real geometries\, internal interfaces\, nonlinear boundary /interface conditions and the presence of disparate spatial and temporal s cales present in real media and sources\, discontinuities and sharp wave f ronts become fundamental features of the solutions. Thus\, high order accu racy\, geometrically flexible and adaptive numerical algorithms are critic al for high fidelity and efficient simulations of wave phenomena in many a pplications. I will present a physics-based numerical flux suitable for in ter-element and boundary conditions in discontinuous Galerkin approximatio ns of first order hyperbolic PDEs. Using this physics-based numerical pena lty-flux\, we will develop a provably energy-stable discontinuous Galerkin approximations of the elastic waves in complex and discontinuous media. By construction the numerical flux is upwind and yields a discrete energy estimate analogous to the continuous energy estimate. The discrete energy estimates hold for conforming and non-conforming curvilinear elements. The ability to handle non-conforming curvilinear meshes allows for flexible a daptive mesh refinement strategies. The numerical scheme have been impleme nted in ExaHyPE\, a simulation engine for hyperbolic PDEs on adaptive stru ctured meshes\, for exa-scale supercomputers. I will show 3D numerical exp eriments demonstrating stability and high order accuracy. Finally\, we pre sent a large scale geophysical regional wave propagation problem in a hete rogeneous Earth model with geologically constrained media heterogeneity an d geometrically complex free-surface topography. X-ALT-DESC:High order accurate and explicit time-stable solvers are well su ited for hyperbolic wave propagation problems. However\, because of the c omplexities of real geometries\, internal interfaces\, nonlinear boundary/ interface conditions and the presence of disparate spatial and temporal sc ales present in real media and sources\, discontinuities and sharp wave fr onts become fundamental features of the solutions. Thus\, high order accur acy\, geometrically flexible and adaptive numerical algorithms are critica l for high fidelity and efficient simulations of wave phenomena in many ap plications. I will present a physics-based numerical flux suitable for int er-element and boundary conditions in discontinuous Galerkin approximation s of first order hyperbolic PDEs. Using this physics-based numerical penal ty-flux\, we will develop a provably energy-stable discontinuous Galerkin approximations of the elastic waves in complex and discontinuous media. B y construction the numerical flux is upwind and yields a discrete energy e stimate analogous to the continuous energy estimate. The discrete energy e stimates hold for conforming and non-conforming curvilinear elements. The ability to handle non-conforming curvilinear meshes allows for flexible ad aptive mesh refinement strategies. The numerical scheme have been implemen ted in ExaHyPE\, a simulation engine for hyperbolic PDEs on adaptive struc tured meshes\, for exa-scale supercomputers. I will show 3D numerical expe riments demonstrating stability and high order accuracy. Finally\, we pres ent a large scale geophysical regional wave propagation problem in a heter ogeneous Earth model with geologically constrained media heterogeneity and geometrically complex free-surface topography. DTEND;TZID=Europe/Zurich:20180601T120000 END:VEVENT BEGIN:VEVENT UID:news183@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175747 DTSTART;TZID=Europe/Zurich:20180531T121500 SUMMARY:Bernoullis Tafelrunde: Rosa Winter DESCRIPTION:Abstract [t3://file?uid=632]\, slides [t3://file?uid=671] X-ALT-DESC: Abstract\, slides DTEND;TZID=Europe/Zurich:20180531T130000 END:VEVENT BEGIN:VEVENT UID:news644@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190125T172712 DTSTART;TZID=Europe/Zurich:20180529T103000 SUMMARY:Seminar Algebra and Geometry: Jérémy Blanc (Basel) DESCRIPTION:I will describe a joint work with Stéphane Lamy and Susanna Zi mmermann which provides abelian quotients of the Cremona groups in high dimension. X-ALT-DESC: I will describe a joint work with Stéphane Lamy and Susanna Zi mmermann which provides abelian quotients of the Cremona groups in high dimension. DTEND;TZID=Europe/Zurich:20180529T120000 END:VEVENT BEGIN:VEVENT UID:news589@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190118T120736 DTSTART;TZID=Europe/Zurich:20180525T171500 SUMMARY:BZ Seminar in Analysis: Rupert Frank (LMU Munich and Caltech) DESCRIPTION:We generalize the Lp spectral cluster bounds of Sogge for the L aplace-Beltrami operator on compact Riemannian manifolds to systems of ort honormal functions. We show that these bounds are optimal on any manifold in a very strong sense. These spectral cluster bounds follow from Schatten -type bounds on oscillatory integral operators and their optimality follow s by semi-classical analysis. The talk is based on joint work with Julien Sabin. X-ALT-DESC: We generalize the Lp spectral cluster bounds of Sogge for the L aplace-Beltrami operator on compact Riemannian manifolds to systems of ort honormal functions. We show that these bounds are optimal on any manifold in a very strong sense. These spectral cluster bounds follow from Schatten -type bounds on oscillatory integral operators and their optimality follow s by semi-classical analysis. The talk is based on joint work with Julien Sabin. DTEND;TZID=Europe/Zurich:20180525T181500 END:VEVENT BEGIN:VEVENT UID:news590@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190118T120802 DTSTART;TZID=Europe/Zurich:20180525T160000 SUMMARY:BZ Seminar in Analysis: David Jerison (MIT) DESCRIPTION:We discuss joint work with Douglas Arnold\, Guy David\, Marcel Filoche and Svitlana Mayboroda. Consider the Neumann boundary value proble m for the operator\\r\\nLu = -div(A∇u) + Vu\\r\\non a Lipschitz domain Ω and\, more generally\, on a manifold with or without boundary. The eige nfunctions of L are often localized\, as a result of disorder of the poten tial V \, the matrix of coefficients A\, irregularities of the boundary\, or all of the above. In earlier work\, Filoche and Mayboroda introduced th e function u solving Lu = 1\, and showed numerically that it strongly refl ects this localization. Here\, we deepen the connection between the eigenf unctions and this landscape function u by proving that its reciprocal 1/u acts as an effective potential. The effective potential governs the expone ntial decay of the eigenfunctions of the system and delivers information o n the distribution of eigenvalues near the bottom of the spectrum. X-ALT-DESC: We discuss joint work with Douglas Arnold\, Guy David\, Marcel Filoche and Svitlana Mayboroda. Consider the Neumann boundary value proble m for the operator\nLu = -div(A∇u) + Vu\non a Lipschitz domain Ω and\, more generally\, on a manifold with or without boundary. The eigenfunction s of L are often localized\, as a result of disorder of the potential V \, the matrix of coefficients A\, irregularities of the boundary\, or all of the above. In earlier work\, Filoche and Mayboroda introduced the functio n u solving Lu = 1\, and showed numerically that it strongly reflects this localization. Here\, we deepen the connection between the eigenfunctions and this landscape function u by proving that its reciprocal 1/u acts as a n effective potential. The effective potential governs the exponential dec ay of the eigenfunctions of the system and delivers information on the dis tribution of eigenvalues near the bottom of the spectrum. DTEND;TZID=Europe/Zurich:20180525T170000 END:VEVENT BEGIN:VEVENT UID:news222@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T180942 DTSTART;TZID=Europe/Zurich:20180525T113000 SUMMARY:Seminar in Numerical Analysis: Ludovic Métivier (Université Greno ble Alpes) DESCRIPTION:Full waveform inversion (FWI) is a powerful high resolution sei smic imaging method\, used in the academy for global and regional scale imaging\, and in the oil & gas industry for exploration purposes. It can be understood as a PDE constrained optimization problem: the misfit betwe en recorded seismic data and synthetic seismic data computed as the solut ion of a wave propagation problem is reduced over a space of parameters c ontrolling the wave propagation. One of the main limitation of FWI is its dependency on the accuracy of the initial guess of the solution. This li mitation is due to the non-convexity of the standard least-squares misfit function used to measure the discrepancy between recorded and synthetic data\, and the use of local optimization techniques to reduce this misfit . In recent studies\, we have studied the interest for using a misfit fun ction based on an optimal transport distance to mitigate this issue. The convexity of this distance with respect to shifted patterns is the main r eason why we are interested in this distance\, as it can be seen as a pro xy for the convexity with respect to the wave velocities we want to reco nstruct. In this talk\, we will give an overview of this work\, starting by introducing basic concepts on optimal transport\, before detailing the difficulties for using the optimal transport distance in the framework o f FWI\, and reviewing the solutions we have proposed. X-ALT-DESC:Full waveform inversion (FWI) is a powerful high resolution seis mic imaging method\, used in the academy for global and regional scale i maging\, and in the oil &\; gas industry for exploration purposes. It can be understood as a PDE constrained optimization problem: the misfit b etween recorded seismic data and synthetic seismic data computed as the s olution of a wave propagation problem is reduced over a space of paramete rs controlling the wave propagation. One of the main limitation of FWI is its dependency on the accuracy of the initial guess of the solution. Thi s limitation is due to the non-convexity of the standard least-squares mi sfit function used to measure the discrepancy between recorded and synthe tic data\, and the use of local optimization techniques to reduce this mi sfit. In recent studies\, we have studied the interest for using a misfit function based on an optimal transport distance to mitigate this issue. The convexity of this distance with respect to shifted patterns is the ma in reason why we are interested in this distance\, as it can be seen as a proxy for the convexity with respect to the wave velocities we want to reconstruct. In this talk\, we will give an overview of this work\, start ing by introducing basic concepts on optimal transport\, before detailing the difficulties for using the optimal transport distance in the framewo rk of FWI\, and reviewing the solutions we have proposed. DTEND;TZID=Europe/Zurich:20180525T123000 END:VEVENT BEGIN:VEVENT UID:news56@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175313 DTSTART;TZID=Europe/Zurich:20180524T150000 SUMMARY:Computer Science Colloquium: Osman Abul DESCRIPTION:Abstract: Location privacy is getting increased attention due t o mass use of Location Based Services (LBSs). Location privacy aims at pro tecting individuals' exact location from LBS providers. For this purpose\, sharing coarse locations respecting users' location privacy profiles are commonly applied. The problem gets more complicated especially in urban ar eas where user movements are restricted on roads and the visited places ar e semantically annotated like bars\, night clubs etc. This way location ca n act as an intrusive inference on people's personal preferences and habit s. So\, location privacy is not confined to privacy of location itself. Mo reover\, any sensitive pattern in users' trajectories can be resurfaced by data mining.In this talk\, especially for urban area mobility\, I will gi ve how location privacy profiles can be defined and maintained w.r.t. poss ible attack models. Then\, I will introduce temporally annotated sequences as a means to define sensitive location patterns. Finally\, a sensitive l ocation pattern suppression mechanism running in online stream fashion of LBS access will be detailed. Speaker Bio: Osman Abul is currently an ass ociate professor of computer science at TOBB University of Economics and T echnology\, Ankara\, Turkey. He received his PhD degree in computer engine ering from Middle East Technical University\, Ankara\, Turkey. He held vis iting posts in University of Calgary\, Norwegian University of Science and Technology\, and Italian Institute of Information Science and Technology. His research interests include data mining\, data privacy and bioinformat ics. X-ALT-DESC:\n

In this talk\, especially for urban area mobili ty\, I will give how location privacy profiles can be defined and maintain ed w.r.t. possible attack models. Then\, I will introduce temporally annot ated sequences as a means to define sensitive location patterns. Finally\, a sensitive location pattern suppression mechanism running in online stre am fashion of LBS access will be detailed. \;

DTEND;TZID=Europe/Zurich:20180524T160000 END:VEVENT BEGIN:VEVENT UID:news181@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175758 DTSTART;TZID=Europe/Zurich:20180524T121500 SUMMARY:Bernoullis Tafelrunde: Silvia Ligabue DESCRIPTION:Abstract [t3://file?uid=613] X-ALT-DESC: Abstract DTEND;TZID=Europe/Zurich:20180524T130000 END:VEVENT BEGIN:VEVENT UID:news643@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190125T172506 DTSTART;TZID=Europe/Zurich:20180522T103000 SUMMARY:Seminar Algebra and Geometry: Andriy Regeta (Köln) DESCRIPTION:In this talk we are going to discuss the following question: t o which extent a so-called Danielewski surface is determined by its autom orphism group seen as an abstract group or as an ind-group? X-ALT-DESC: In this talk we are going to discuss the following question: t o which extent a so-called Danielewski surface is determined by its autom orphism group seen as an abstract group or as an ind-group? DTEND;TZID=Europe/Zurich:20180522T120000 END:VEVENT BEGIN:VEVENT UID:news221@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T175831 DTSTART;TZID=Europe/Zurich:20180518T110000 SUMMARY:Seminar in Numerical Analysis: Holger Fröning (Universität Heidel berg) DESCRIPTION:We are observing a continuous increase in concurrency and heter ogeneity for computing systems of any scale\, ranging from small mobile de vices to huge datacenters\, and driven by a steady demand for more computi ng power. One of the prime examples for an application with virtually unli mited computational requirements is machine learning\, in particular deep neural networks (DNN). At the level of data-centers\, DNN training has alr eady led to a ubiquitous use of graphics processing units (GPUs)\, forming a prime example for specialization for computational improvement. Still\, this application is strongly hindered by insufficient compute power and b y scalability limitations. Contrary\, mobile architectures for DNN inferen ce are still nascent\, and a large amount of proposals have been published in the recent years. Both applications\, training and inference\, can fur thermore benefit a lot from algorithmic optimizations to reduce the comput ational requirements. This talk presents a short introduction of the appli cation\, a summary of our observations\, and our own research on reduced p recision by extreme forms of quantizations. Finally\, this talk will offer some opinions on anticipated research problems. X-ALT-DESC:We are observing a continuous increase in concurrency and hetero geneity for computing systems of any scale\, ranging from small mobile dev ices to huge datacenters\, and driven by a steady demand for more computin g power. One of the prime examples for an application with virtually unlim ited computational requirements is machine learning\, in particular deep n eural networks (DNN). At the level of data-centers\, DNN training has alre ady led to a ubiquitous use of graphics processing units (GPUs)\, forming a prime example for specialization for computational improvement. Still\, this application is strongly hindered by insufficient compute power and by scalability limitations. Contrary\, mobile architectures for DNN inferenc e are still nascent\, and a large amount of proposals have been published in the recent years. Both applications\, training and inference\, can furt hermore benefit a lot from algorithmic optimizations to reduce the computa tional requirements. This talk presents a short introduction of the applic ation\, a summary of our observations\, and our own research on reduced pr ecision by extreme forms of quantizations. Finally\, this talk will offer some opinions on anticipated research problems. DTEND;TZID=Europe/Zurich:20180518T120000 END:VEVENT BEGIN:VEVENT UID:news195@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T173706 DTSTART;TZID=Europe/Zurich:20180517T161500 SUMMARY:Public Inaugural Lecture PD Dr. Jung-Kyu Canci: Dynamical systems w ith a view toward arithmetic DESCRIPTION:A dynamical system is essentially the repeated iteration of an action.The study of dynamical systems has a long history. Many people cons ider Henri Poincaré as the founder (at the end of the 19th century) of th e modern theory of dynamical systems. Further important contributions at t he beginning of the 20th are due to George David Birkhoff\, Gaston Julia a nd Pierre Fatou.In the talk we will discuss some aspects of the theory of dynamical systems with a view toward arithmetic. As an example we will sho w that Birkhoff's multiple recurrence Theorem can be used to provide an al ternative proof of van der Waerden's Theorem on arithmetic progressions. W e will also show that Julia sets are useful to understand the dynamic give n by a rational function. X-ALT-DESC:A dynamical system is essentially the repeated iteration of an a ction.

The study of dynamical systems has a long history. Many people consider Henri Poincaré as the founder (at the end of the 19th cen tury) of the modern theory of dynamical systems. Further important contrib utions at the beginning of the 20th are due to George David Birkhoff\, Gas ton Julia and Pierre Fatou.

In the talk we will discuss some as pects of the theory of dynamical systems with a view toward arithmetic. As an example we will show that Birkhoff's multiple recurrence Theorem can b e used to provide an alternative proof of van der Waerden's Theorem on ari thmetic progressions. We will also show that Julia sets are useful to unde rstand the dynamic given by a rational function. DTEND;TZID=Europe/Zurich:20180517T171500 END:VEVENT BEGIN:VEVENT UID:news97@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175807 DTSTART;TZID=Europe/Zurich:20180517T121500 SUMMARY:Bernoullis Tafelrunde: Rémi Bignalet-Cazalet DESCRIPTION:Abstract [t3://file?uid=460]\, slides [t3://file?uid=550] X-ALT-DESC: Abstract\, slides DTEND;TZID=Europe/Zurich:20180517T130000 END:VEVENT BEGIN:VEVENT UID:news642@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190125T172321 DTSTART;TZID=Europe/Zurich:20180515T103000 SUMMARY:Seminar Algebra and Geometry: Peter Feller (ETHZ) DESCRIPTION:We start by recalling that a smooth algebraic curve of degree d in CP2 is a genus (d-1)(d-2)/2 surface (read `smooth 2-manifold'). The ` Thom Conjecture'\, proven by Kronheimer and Mrowka\, asserts that such al gebraic curves have a surprising minimizing property. We derive consequenc es of the Thom Conjecture for transversal intersections of algebraic curv es with round spheres\, describe the knots one finds as such intersection s following Rudolph\, and give precise instances of the sentiment that th ese intersections constitute very special elements in the so-called smoot h concordance group. In contrast\, in the topological category\, we prove that all knots are topological concordant to such an intersection. Based on joint work with Maciej Borodzik. No knowledge about knot theory and co ncordance theory---the study of 1-manifolds in the 3-dimensional sphere a nd surfaces in 4-dimensional ball bounding them---will be assumed. X-ALT-DESC: We start by recalling that a smooth algebraic curve of degree d in CP

In the cu rrent joint project with Laurent Gruson and Nicolas Perrin\, we study some examples of Fano varieties in low dimension via explicit birational metho ds. DTEND;TZID=Europe/Zurich:20180417T120000 END:VEVENT BEGIN:VEVENT UID:news218@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T180010 DTSTART;TZID=Europe/Zurich:20180413T110000 SUMMARY:Seminar in Numerical Analysis: Philipp Morgenstern (Leibniz Univers ität Hannover) DESCRIPTION:We introduce a mesh refinement algorithm for the Adaptive Isoge ometric Method using multivariate T-splines. We investigate linear indepen dence of the T-splines\, nestedness of the T-spline spaces\, and linear co mplexity in the sense of a uniform upper bound on the ratio of generated a nd marked elements\, which is crucial for a later proof of rate-optimality of the method. Altogether\, this work paves the way for a provably rate-o ptimal Adaptive Isogeometric Method with T-splines in any space dimension. \\r\\nAs an outlook to future work\, we outline an approach for the handli ng of zero knot intervals and multiple lines in the interior of the domain \, which are used in CAD applications for controlling the continuity of th e spline functions\, and we also sketch basic ideas for the local refineme nt of two-dimensional meshes that do not have tensor-product structure. X-ALT-DESC:We introduce a mesh refinement algorithm for the Adaptive Isogeo metric Method using multivariate T-splines. We investigate linear independ ence of the T-splines\, nestedness of the T-spline spaces\, and linear com plexity in the sense of a uniform upper bound on the ratio of generated an d marked elements\, which is crucial for a later proof of rate-optimality of the method. Altogether\, this work paves the way for a provably rate-op timal Adaptive Isogeometric Method with T-splines in any space dimension.\ nAs an outlook to future work\, we outline an approach for the handling of zero knot intervals and multiple lines in the interior of the domain\, wh ich are used in CAD applications for controlling the continuity of the spl ine functions\, and we also sketch basic ideas for the local refinement of two-dimensional meshes that do not have tensor-product structure. DTEND;TZID=Europe/Zurich:20180413T120000 END:VEVENT BEGIN:VEVENT UID:news113@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175843 DTSTART;TZID=Europe/Zurich:20180412T121500 SUMMARY:Bernoullis Tafelrunde: Harprit Singh DESCRIPTION:Abstract [t3://file?uid=511]\, slides [t3://file?uid=513] X-ALT-DESC:Abstract\, slides DTEND;TZID=Europe/Zurich:20180412T130000 END:VEVENT BEGIN:VEVENT UID:news633@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190125T172302 DTSTART;TZID=Europe/Zurich:20180403T103000 SUMMARY:Seminar Algebra and Geometry: Pierre-Marie Poloni (Bern) DESCRIPTION:An $\\mathbb{A}^2$-fibration is a flat morphism between complex affine varieties whose fibers are isomorphic to the complex affine plane . In this talk\, we study explicit families $f:\\mathbb{A}^4\\to\\mathbb{ A}^2$ of $\\mathbb{A}^2$-fibrations over the affine plane. The famous Dol gachev-Weisfeiler conjecture predicts that such fibrations are in fact is omorphic to the trivial bundle. We will show that this holds true in some particular examples. For instance\, we will recover a result of Drew Lew is which states that the $\\mathbb{A}^2$-fibration induced by the second Vénéreau polynomial is trivial. Our proof is inspired by a previous work of Kaliman and Zaidenberg and consists in first showing that the conside red fibrations have a fiber bundle structure when restricted over the pun ctured affine plane. This is a joint work in progress with Jérémy Blanc. X-ALT-DESC:An $\\mathbb{A}^2$-fibration is a flat morphism between complex affine varieties whose fibers are isomorphic to the complex affine plane. In this talk\, we study explicit families $f:\\mathbb{A}^4\\to\\mathbb{A }^2$ of $\\mathbb{A}^2$-fibrations over the affine plane.

The famou s Dolgachev-Weisfeiler conjecture predicts that such fibrations are in fa ct isomorphic to the trivial bundle. We will show that this holds true in some particular examples. For instance\, we will recover a result of Dre w Lewis which states that the $\\mathbb{A}^2$-fibration induced by the se cond Vénéreau polynomial is trivial.

Our proof is inspired by a pr evious work of Kaliman and Zaidenberg and consists in first showing that the considered fibrations have a fiber bundle structure when restricted o ver the punctured affine plane.

This is a joint work in progress wit h Jérémy Blanc. DTEND;TZID=Europe/Zurich:20180403T120000 END:VEVENT BEGIN:VEVENT UID:news217@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T174831 DTSTART;TZID=Europe/Zurich:20180323T110000 SUMMARY:Seminar in Numerical Analysis: Gregor Gantner (TU Wien) DESCRIPTION:Since the advent of isogeometric analysis (IGA) in 2005\, the f inite element method (FEM) and the boundary element method (BEM) with spli nes have become an active field of research. The central idea of IGA is to use the same functions for the approximation of the solution of the consi dered partial differential equation (PDE) as for the representation of the problem geometry in computer aided design (CAD). Usually\, CAD is based o n tensor-product splines. To allow for adaptive refinement\, several exten sions of these have emerged\, e.g.\, hierarchical splines\, T-splines\, an d LR-splines. In view of geometry induced generic singularities and the fa ct that isogeometric methods employ higher-order ansatz functions\, the ga in of adaptive refinement (resp. loss for uniform refinement) is huge.\\r\ \nIn this talk\, we first consider an adaptive FEM with hierarchical splin es of arbitrary degree for linear elliptic PDE systems of second order wit h Dirichlet boundary condition for arbitrary dimension d≥2. We assume th at the problem geometry can be parametrized over the d-dimensional unit cu be. We propose a refinement strategy to generate a sequence of locally ref ined meshes and corresponding discrete solutions. Adaptivity is driven by some weighted-residual a posteriori error estimator. In [1]\, we proved li near convergence of the error estimator with optimal algebraic rate.\\r\\n Next\, we consider an adaptive BEM with hierarchical splines of arbitrary degree for weakly-singular integral equations of the first kind that arise from the solution of linear elliptic PDE systems of second order with con stant coefficients and Dirichlet boundary condition. We assume that the bo undary of the geometry is the union of surfaces that can be parametrized o ver the unit square. Again\, we propose a refinement strategy to generate a sequence of locally refined meshes and corresponding discrete solutions\ , where adaptivity is driven by some weighted-residual a posteriori error estimator. In [2]\, we proved linear convergence of the error estimator wi th optimal algebraic rate. In contrast to prior works\, which are restrict ed to the Laplace model problem\, our analysis allows for arbitrary ellipt ic PDE operators of second order with constant coefficients.\\r\\nFinally\ , for one-dimensional boundaries\, we investigate an adaptive BEM with sta ndard splines instead of hierarchical splines. We modify the corresponding algorithm so that it additionally uses knot multiplicity increase which r esults in local smoothness reduction of the ansatz space. In [3]\, we prov ed linear convergence of the employed weighted-residual error estimator wi th optimal algebraic rate.\\r\\nREFERENCES\\r\\n[1] G. Gantner\, D. Haberl ik\, and Dirk Praetorius\, Adaptive IGAFEM with optimal convergence rates: Hierarchical B-splines. Math. Mod. Meth. in Appl. S.\, Vol. 27\, 2017.\\r \\n[2] G. Gantner\, Optimal adaptivity for splines in finite and boundary element methods\, PhD thesis\, TU Wien\, 2017.\\r\\n[3] Michael Feischl\, Gregor Gantner\, Alexander Haberl\, and Dirk Praetorius. Adaptive 2D IGA b oundary element methods. Eng. Anal. Bound. Elem.\, Vol. 62\, 2016. X-ALT-DESC:Since the advent of isogeometric analysis (IGA) in 2005\, the fi nite element method (FEM) and the boundary element method (BEM) with splin es have become an active field of research. The central idea of IGA is to use the same functions for the approximation of the solution of the consid ered partial differential equation (PDE) as for the representation of the problem geometry in computer aided design (CAD). Usually\, CAD is based on tensor-product splines. To allow for adaptive refinement\, several extens ions of these have emerged\, e.g.\, hierarchical splines\, T-splines\, and LR-splines. In view of geometry induced generic singularities and the fac t that isogeometric methods employ higher-order ansatz functions\, the gai n of adaptive refinement (resp. loss for uniform refinement) is huge.\nIn this talk\, we first consider an adaptive FEM with hierarchical splines of arbitrary degree for linear elliptic PDE systems of second order with Dir ichlet boundary condition for arbitrary dimension d≥2. We assume that th e problem geometry can be parametrized over the d-dimensional unit cube. W e propose a refinement strategy to generate a sequence of locally refined meshes and corresponding discrete solutions. Adaptivity is driven by some weighted-residual a posteriori error estimator. In [1]\, we proved linear convergence of the error estimator with optimal algebraic rate.\nNext\, we consider an adaptive BEM with hierarchical splines of arbitrary degree fo r weakly-singular integral equations of the first kind that arise from the solution of linear elliptic PDE systems of second order with constant coe fficients and Dirichlet boundary condition. We assume that the boundary of the geometry is the union of surfaces that can be parametrized over the u nit square. Again\, we propose a refinement strategy to generate a sequenc e of locally refined meshes and corresponding discrete solutions\, where a daptivity is driven by some weighted-residual a posteriori error estimator . In [2]\, we proved linear convergence of the error estimator with optima l algebraic rate. In contrast to prior works\, which are restricted to the Laplace model problem\, our analysis allows for arbitrary elliptic PDE op erators of second order with constant coefficients.\nFinally\, for one-dim ensional boundaries\, we investigate an adaptive BEM with standard splines instead of hierarchical splines. We modify the corresponding algorithm so that it additionally uses knot multiplicity increase which results in loc al smoothness reduction of the ansatz space. In [3]\, we proved linear con vergence of the employed weighted-residual error estimator with optimal al gebraic rate.\n

Partic ular applications include pathfinding and planning in memory-constrained r eal-time environments (e.g. commercial video games) as well as algorithms for building and using memory-based heuristics via large-scale search. Oth er work considers theoretical and practical issues in games with more than two players\, including opponent modeling\, learning\, and imperfect info rmation. DTEND;TZID=Europe/Zurich:20180227T140000 END:VEVENT BEGIN:VEVENT UID:news148@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175852 DTSTART;TZID=Europe/Zurich:20171214T121500 SUMMARY:Bernoullis Tafelrunde: Sara Durighetto DESCRIPTION:Abstract [t3://file?uid=592] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20171214T130000 END:VEVENT BEGIN:VEVENT UID:news652@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190126T193831 DTSTART;TZID=Europe/Zurich:20171212T103000 SUMMARY:Seminar Algebra and Geometry: Sara Durighetto (Ferrara) DESCRIPTION:Let C\, D be two birational subvarieties of the projective spac e Pn. I am interested in understanding when there exists a Cremona modif ication f: Pn --->Pn such that f(C) = D. For the sake of this talk I will restrict to a configuration of lines in P2. In this special case I'll suggest a classification of configurations of lines that are c ontractible to a bunch of points. In doing this I will propose an unexpec ted configuration that seems to violate an established conjecture. X-ALT-DESC: Let C\, D be two birational subvarieties of the projective spac e \;

A striking consequence is th e following result.

Theorem. Let n >\; 4. Then a smooth $\\SL_n$-v ariety of dimension d <\; 2n-2 is an $\\SL_n$-vector bundle over a smoo th variety of dimension d-n. There are also interesting applications to a ctions of the affine group $\\Aff_n$. This was the starting point of this joint work with with Andriy Regeta and Susanna Zimmermann. DTEND;TZID=Europe/Zurich:20170926T120000 END:VEVENT BEGIN:VEVENT UID:news530@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T072958 DTSTART;TZID=Europe/Zurich:20170922T161500 SUMMARY:Doktorkolloquium Mathematik: Jürgen Dölz DTEND;TZID=Europe/Zurich:20170922T171500 END:VEVENT BEGIN:VEVENT UID:news153@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T175959 DTSTART;TZID=Europe/Zurich:20170921T121500 SUMMARY:Bernoullis Tafelrunde: Lea Multerer DESCRIPTION:Abstract [t3://file?uid=589] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20170921T130000 END:VEVENT BEGIN:VEVENT UID:news645@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190125T173135 DTSTART;TZID=Europe/Zurich:20170919T103000 SUMMARY:Seminar Algebra and Geometry: Anne Lonjou (Basel) DESCRIPTION:The Cremona group is the group of birational transformations of the projective plane. It acts on a hyperbolic space which is an infinite dimensional version of the hyperboloid model of Hn. This action is the main recent tool to study the Cremona group. After defining it\, we will study its Voronoï tesselation\, and describe some graphs naturally assoc iated with this construction. Finally we will discuss which of these grap hs are Gromov-hyperbolic. X-ALT-DESC: The Cremona group is the group of birational transformations of the projective plane. It acts on a hyperbolic space which is an infinite dimensional version of the hyperboloid model of H

We are interested in cycles of φ

Arnaud Beauville proved that all but four of t hese quartic threeffolds are irrational. Later Cheltsov and Shramov prove d that the remaining threefolds in this pencil are rational. In this talk \, I will give an alternative prove of both these results. To do this\, I will describe Q-factorizations of the double cover of the four-dimension al projective space branched over the Igusa quartic\, which is known as C oble fourfold. Using this\, I will show that $\\mathbb{S}_6$-symmetric qua rtic threefolds are birational to conic bundles over quintic del Pezzo su rfaces whose degeneration curves are contained in the pencil studied by W iman and Edge.

This is a joint work with Alexander Kuznetsov and Con stantin Shramov (Moscow). DTEND;TZID=Europe/Zurich:20170505T120000 END:VEVENT BEGIN:VEVENT UID:news176@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T181908 DTSTART;TZID=Europe/Zurich:20170504T120500 SUMMARY:Bernoullis Tafelrunde: Christine Bürli DESCRIPTION:Abstract [t3://file?uid=575] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20170504T125000 END:VEVENT BEGIN:VEVENT UID:news430@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181217T194233 DTSTART;TZID=Europe/Zurich:20170503T141500 SUMMARY:Seminar Analysis: Joaquim Serra (ETH Zurich) DESCRIPTION:We will introduce some recent results in collaboration with L. Caffarelli and X. Ros-Otonon the optimal regularity of the solutions and the regularity of the free boundaries (near regular points) f or nonlocal obstacle problems.The main novelty is that we obtain re sults for different operators than the fractional Laplacian. Indee d\, we can consider infinitesimal generators of non rotationally invariant stable L ́evy processes. X-ALT-DESC:\nWe will introduce some recent results in collaboration with L. Caffarelli and X. Ros-Otonon the optimal regularity of the solution s and the regularity of the free boundaries (near regular points) for nonlocal obstacle problems.The main novelty is that we obtain r esults for different operators than the fractional Laplacian. Inde ed\, we can consider infinitesimal generators of non rotationally invariant stable L ́evy processes. DTEND;TZID=Europe/Zurich:20170503T151500 END:VEVENT BEGIN:VEVENT UID:news657@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T221448 DTSTART;TZID=Europe/Zurich:20170428T103000 SUMMARY:Seminar Algebra and Geometry: Marcello Bernardara (Toulouse) DESCRIPTION:Let X be a smooth projective variety over a field k\, and assum e that weak factorization holds (e.g.\, k has characteristic zero).I will introduce the Grothendieck ring of triangulated categories\, and show ho w\, using Bondal-Larsen-Lunts motivic measure\, a subgroup of such ring w ill define a subgroup of the group Bir(X) of birational self-maps of X. A main example is given by the filtration via the motivic dimension\, whic h induces a filtration on Bir(X). As a consequence\, in the case X=Pn\, w e can show that the group generated by the standard Cremona transformatio n and PGL(n+1) is strictly contained in the group contracting rational va rieties\, as soon as n > 4. Another example allows to reconstruct Frumkin 's genus filtration of Bir(X) in the cases where X is a uniruled threefol d. X-ALT-DESC: Let X be a smooth projective variety over a field k\, and assum e that weak factorization holds (e.g.\, k has characteristic zero).

I will introduce the Grothendieck ring of triangulated categories\, and s how how\, using Bondal-Larsen-Lunts motivic measure\, a subgroup of such ring will define a subgroup of the group Bir(X) of birational self-maps o f X. A main example is given by the filtration via the motivic dimension\ , which induces a filtration on Bir(X). As a consequence\, in the case X= P

The former moduli spa ce is itself related to the moduli space of rank 2 parabolic bundles over a 5-punctured P

recap of prope rties of (relative) entropy\, the following \;examples of irreversible behavior are discussed:

(1) The second law of thermodynamics is disc ussed within \;quantum statistical mechanics.

(2) It is indicate d how Brownian motion of a quantum particle \;immersed in a heat bath can be derived from unitary quantum \;dynamics of the total system.< br />(3) Motion with friction is discussed in an example of Hamiltonian&n bsp\;evolution equations for a particle moving through a dispersive \ ;wave medium.

(4) It is sketched that and why quantum dynamics is fun damentally \;irreversible. DTEND;TZID=Europe/Zurich:20170420T171500 END:VEVENT BEGIN:VEVENT UID:news174@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T181927 DTSTART;TZID=Europe/Zurich:20170420T120500 SUMMARY:Bernoullis Tafelrunde: Nestor Fernandez Vargas DESCRIPTION:Abstract [t3://file?uid=583] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20170420T125000 END:VEVENT BEGIN:VEVENT UID:news429@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181217T193706 DTSTART;TZID=Europe/Zurich:20170419T141500 SUMMARY:Seminar Analysis: Dominik Himmelsbach (University of Basel) DESCRIPTION:In this talk\, we give sufficient criteria for blowup of solutions to nonlocal Schrödinger equations with focusing power-ty pe nonlinearity. To give an outline of the arguments used in the proof\, let us mainly focus on the mass-supercritical problem posed on the whole s pace Rn with prescribed radial initial datum of negative energy.\\r\\nThis is a joint work with Thomas Boulenger and Enno Lenzmann X-ALT-DESC:\nIn this talk\, we give sufficient criteria for blowup of solutions to nonlocal Schrödinger equations with focusing power-t ype nonlinearity. To give an outline of the arguments used in the proof\, let us mainly focus on the mass-supercritical problem posed on the whole space R

(Joint work with Ada Boralevi\, Emil Horobet\, and Elina Robeva.) DTEND;TZID=Europe/Zurich:20170303T120000 END:VEVENT BEGIN:VEVENT UID:news536@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T080011 DTSTART;TZID=Europe/Zurich:20170302T161500 SUMMARY:Perlen-Kolloquium: Eitan Tadmor (University of Maryland & ETH-ITS) DESCRIPTION:Self-organization is observed in systems driven by the “social engagement”of agents with their local neighbors. Protot ypical models are found in opinion dynamics\, flocking\,self-organi zation of biological organisms\, and rendezvous in mobile networks.We disc uss the emergent behavior of such systems. Two natural questions arise in this context. The underlying issue of the first question is how di fferent rules of engagement influence the formation of clusters\, an d in particular\, the emergence of ‘consensus’. Different paradigms of emergence yield different patterns\, depending on the propagation o f connectivity of the underlying graphs of communication. The secon d question involves different descriptions of self-organized dynamics when the number of agents tends to infinity. It lends itself to “social hydr odynamics”\, driven by the corresponding tendency to move towards the lo cal means.We discuss the global regularity of social hydrodynamics for sub -critical initial configurations. X-ALT-DESC: Self-organization is observed in systems driven by the “social engagement”of agents with their local neighbors. Protot ypical models are found in opinion dynamics\, flocking\,self-organi zation of biological organisms\, and rendezvous in mobile networks.We disc uss the emergent behavior of such systems. Two natural questions arise in this context. The underlying issue of the first question is how di fferent rules of engagement influence the formation of clusters\, an d in particular\, the emergence of ‘consensus’. Different paradigms of emergence yield different patterns\, depending on the propagation o f connectivity of the underlying graphs of communication. The secon d question involves different descriptions of self-organized dynamics when the number of agents tends to infinity. It lends itself to “social hydr odynamics”\, driven by the corresponding tendency to move towards the lo cal means.We discuss the global regularity of social hydrodynamics for sub -critical initial configurations. DTEND;TZID=Europe/Zurich:20170302T171500 END:VEVENT BEGIN:VEVENT UID:news168@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182018 DTSTART;TZID=Europe/Zurich:20170302T120500 SUMMARY:Bernoullis Tafelrunde: Aline Steiner DESCRIPTION:Abstract [t3://file?uid=574] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20170302T125000 END:VEVENT BEGIN:VEVENT UID:news425@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181217T192300 DTSTART;TZID=Europe/Zurich:20170301T141500 SUMMARY:Seminar Analysis: Isabella Ianni (University of Naples II) DESCRIPTION:We consider the semilinear Lane-Emden problem (Ep):\\r\\n-Δu = |u|p-1u in B u = 0 on ∂B\\r\\nwhere B is the unit ball of RN\, N≥3\, centered at the origin and 1< p < pS\, p S=(N+2)/(N−2). We compute the Morse index of any radial solution up of (Ep)\, for p sufficiently close to pS. The proof exploits the a symptotic behavior of up as p→pS and the analysis of a limit eigenvalue problem.\\r\\nThis is a joint work with F. De Marchis and F. Pacella X-ALT-DESC:\nWe consider the semilinear Lane-Emden problem (E

\;& nbsp\; u = 0 \; \; \; \; \; \; \; \; \ ; \; \; on ∂B\nwhere B is the unit ball of R

Thi s is based on a joint work with Vincent Guedj. DTEND;TZID=Europe/Zurich:20161216T153000 END:VEVENT BEGIN:VEVENT UID:news232@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T203725 DTSTART;TZID=Europe/Zurich:20161216T110000 SUMMARY:Seminar in Numerical Analysis: Christian Rieger (Universität Bonn) DESCRIPTION:In this talk\, we will briefly discuss a general methodology of approximation algorithms based on reproducing kernels and their associa ted Hilbert spaces. We will outline how reproducing kernels naturally ari se in many reconstruction problems.\\r\\nFurthermore\, we will present a d eterministic a priori (often exponential) convergence analysis via sampli ng inequalities which can be employed to analyze a large class of regular ized reconstruction schemes.\\r\\nSuch an analysis enables us to derive a priori couplings of various discretization and regularization parameters . Such parameters can range from iteration numbers in numerical linear al gebra\, numerical evaluation of input parameters to rounding errors.\\r\\ nAn important issue is the choice of the reproducing kernel. We will disc uss some implications of such choices and address the problem of approxim ating the solution of a parametric partial differential equation using pr oblem adapted kernels.\\r\\nThis is partly based on joint work with M. Gri ebel and B. Zwicknagl (both Bonn University). X-ALT-DESC:In this talk\, we will briefly discuss a general methodology of approximation algorithms based on reproducing kernels and their associat ed Hilbert spaces. We will outline how reproducing kernels naturally aris e in many reconstruction problems.\nFurthermore\, we will present a determ inistic a priori (often exponential) convergence analysis via sampling in equalities which can be employed to analyze a large class of regularized reconstruction schemes.\nSuch an analysis enables us to derive a priori c ouplings of various discretization and regularization parameters. Such pa rameters can range from iteration numbers in numerical linear algebra\, n umerical evaluation of input parameters to rounding errors.\nAn important issue is the choice of the reproducing kernel. We will discuss some impl ications of such choices and address the problem of approximating the sol ution of a parametric partial differential equation using problem adapted kernels.\nThis is partly based on joint work with M. Griebel and B. Zwick nagl (both Bonn University). DTEND;TZID=Europe/Zurich:20161216T120000 END:VEVENT BEGIN:VEVENT UID:news669@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225059 DTSTART;TZID=Europe/Zurich:20161216T103000 SUMMARY:Seminar Algebra and Geometry: Zsolt Patakfalvi (EPFL) DESCRIPTION:Stable varieties are higher dimensional generalizations of stab le curves. Their moduli space contains an open locus parametrizing varie ties of general type up to birational equivalence\, just as the space of stable curves contains the space of smooth curves in dimension one. Furth ermore\, also similarly to the one dimensional picture\, it provides a co mpactification of the above locus\, which is known in characteristic zero but it is only conjectural in positive characteristic in dimension at le ast two. I will present a work in progress aiming to prove the projectivi ty of every proper subspace of the moduli space of stable surfaces in cha racteristic greater than 5. X-ALT-DESC: Stable varieties are higher dimensional generalizations of stab le curves. Their moduli space contains an open locus parametrizing varie ties of general type up to birational equivalence\, just as the space of stable curves contains the space of smooth curves in dimension one. Furth ermore\, also similarly to the one dimensional picture\, it provides a co mpactification of the above locus\, which is known in characteristic zero but it is only conjectural in positive characteristic in dimension at le ast two. I will present a work in progress aiming to prove the projectivi ty of every proper subspace of the moduli space of stable surfaces in cha racteristic greater than 5. DTEND;TZID=Europe/Zurich:20161216T120000 END:VEVENT BEGIN:VEVENT UID:news537@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T080302 DTSTART;TZID=Europe/Zurich:20161215T161500 SUMMARY:DMI Kolloquium: Florina Ciorba und Philipp Habegger DTEND;TZID=Europe/Zurich:20161215T171500 END:VEVENT BEGIN:VEVENT UID:news437@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181219T165220 DTSTART;TZID=Europe/Zurich:20161214T141500 SUMMARY:Seminar Analysis: Aleks Jevnikar (University of Rome\, Tor Vergata) DESCRIPTION:A class of Liouville equations and systems on compact surfaces is considered: we focus on the Toda system which is motivated in mathemati cal physics by the study of models in non-abelian Chern-Simons theory and in geometry in the description of holomorphic curves in complex analysis. We discuss its variational aspects which yield existence results. X-ALT-DESC:\nA class of Liouville equations and systems on compact surfaces is considered: we focus on the Toda system which is motivated in mathemat ical physics by the study of models in non-abelian Chern-Simons theory and in geometry in the description of holomorphic curves in complex analysis. We discuss its variational aspects which yield existence results. \; DTEND;TZID=Europe/Zurich:20161214T141500 END:VEVENT BEGIN:VEVENT UID:news166@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182036 DTSTART;TZID=Europe/Zurich:20161214T131500 SUMMARY:Bernoullis Tafelrunde: Julia Schneider DESCRIPTION:Abstract [t3://file?uid=566] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161214T140000 END:VEVENT BEGIN:VEVENT UID:news233@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T203922 DTSTART;TZID=Europe/Zurich:20161209T110000 SUMMARY:Seminar in Numerical Analysis: Daniel Peterseim (Universität Bonn) DESCRIPTION:This talk presents a variational approach for the numerical ho mogenization of elliptic partial differential equations with arbitrary ro ugh diffusion coefficients. The trial and test space in this (Petrov-)Gal erkin method are derived from linear finite elements on a coarse mesh of width H by local fine-scale correction. The correction is based on the pr e-computation of cell problems on patches of diameter H log(1/H). The mod erate overlap of the patches suffices to prove O(H) convergence of the me thod without any pre-asymptotic effects. The key step in the error analys is is the proof of the exponential decay of the so-called fine-scale Gree n's function\, i.e.\, the impulse response of the variational equation in the absence of coarse-scale finite element functions. The method allows the characterization of effective coefficients on a given target scale of numerical resolution. Among further applications of the approach are pol lution-free high-frequency scattering and explicit time stepping on spati ally adaptive meshes. X-ALT-DESC:This talk presents a variational approach for the numerical hom ogenization of elliptic partial differential equations with arbitrary rou gh diffusion coefficients. The trial and test space in this (Petrov-)Gale rkin method are derived from linear finite elements on a coarse mesh of w idth H by local fine-scale correction. The correction is based on the pre -computation of cell problems on patches of diameter H log(1/H). The mode rate overlap of the patches suffices to prove O(H) convergence of the met hod without any pre-asymptotic effects. The key step in the error analysi s is the proof of the exponential decay of the so-called fine-scale Green 's function\, i.e.\, the impulse response of the variational equation in the absence of coarse-scale finite element functions. The method allows t he characterization of effective coefficients on a given target scale of numerical resolution. Among further applications of the approach are poll ution-free high-frequency scattering and explicit time stepping on spatia lly adaptive meshes. DTEND;TZID=Europe/Zurich:20161209T120000 END:VEVENT BEGIN:VEVENT UID:news668@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225134 DTSTART;TZID=Europe/Zurich:20161209T103000 SUMMARY:Seminar Algebra and Geometry: Peter Feller (Bonn) DESCRIPTION:After a brief introduction to plane curve singularities\, we re cast some of their classical invariants in terms of modern knot theory. T hen we will see connections between purely algebraic questions about def ormations of singularities and purely knot theoretic questions about cobo rdisms between knots\, and answer some of them. This talk aims to be elem entary and will not assume familiarity with knot theory or singularity th eory. X-ALT-DESC: After a brief introduction to plane curve singularities\, we re cast some of their classical invariants in terms of modern knot theory. T hen we will see connections between purely algebraic questions about def ormations of singularities and purely knot theoretic questions about cobo rdisms between knots\, and answer some of them. This talk aims to be elem entary and will not assume familiarity with knot theory or singularity th eory. DTEND;TZID=Europe/Zurich:20161209T120000 END:VEVENT BEGIN:VEVENT UID:news538@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T080518 DTSTART;TZID=Europe/Zurich:20161208T161500 SUMMARY:Perlen-Kolloquium: Laure Saint-Raymond (Université Paris VI – P. et M. Curie & École Normale Supérieure de Paris & Universität Zürich) DESCRIPTION:About irreversibility in rarefied gas dynamics X-ALT-DESC:About irreversibility in rarefied gas dynamics DTEND;TZID=Europe/Zurich:20161208T171500 END:VEVENT BEGIN:VEVENT UID:news234@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T204059 DTSTART;TZID=Europe/Zurich:20161202T110000 SUMMARY:Seminar in Numerical Analysis: Xavier Antoine (Université de Lorra ine) DESCRIPTION:The aim of this talk is to introduce nonoverlapping Schwarz dom ain decomposition methods for time harmonic waves (acoustics\, electroma gnetism). In particular\, we will focus on the construction of rational Padé transmission boundary conditions to get fast converging solvers fo r prospecting high frequency problems. Some numerical simulations will il lustrate the theoretical developments. The methods have been implemented in a freely available software called GetDDM. X-ALT-DESC:The aim of this talk is to introduce nonoverlapping Schwarz doma in decomposition methods for time harmonic waves (acoustics\, electromag netism). In particular\, we will focus on the construction of \; rati onal Padé transmission boundary conditions to get fast converging solver s for prospecting high frequency problems. Some numerical simulations wil l illustrate the theoretical developments. The methods have been implemen ted in a freely available software called GetDDM. DTEND;TZID=Europe/Zurich:20161202T120000 END:VEVENT BEGIN:VEVENT UID:news539@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T081047 DTSTART;TZID=Europe/Zurich:20161201T171500 SUMMARY:DMI Kolloquium: Jérémy Blanc und Malte Helmert DTEND;TZID=Europe/Zurich:20161201T181500 END:VEVENT BEGIN:VEVENT UID:news436@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181219T165028 DTSTART;TZID=Europe/Zurich:20161130T141500 SUMMARY:Seminar Analysis: Daniel Ueltschi (University of Warwick) DESCRIPTION:The basic laws governing atoms and electrons are well understoo d\, but it is impossible to make predictions about the behaviour of large systems of condensed matter physics. A popular approach is to introduce si mple models and to use notions of statistical mechanics. I will review qua ntum spin systems and their stochastic representations in terms of random permutations and random loops. I will also describe the ‘universal’ be haviour that is common to loop models in dimensions 3 and more. X-ALT-DESC:\nThe basic laws governing atoms and electrons are well understo od\, but it is impossible to make predictions about the behaviour of large systems of condensed matter physics. A popular approach is to introduce s imple models and to use notions of statistical mechanics. I will review qu antum spin systems and their stochastic representations in terms of random permutations and random loops. I will also describe the ‘universal’ b ehaviour that is common to loop models in dimensions 3 and more. \; DTEND;TZID=Europe/Zurich:20161130T151500 END:VEVENT BEGIN:VEVENT UID:news165@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182046 DTSTART;TZID=Europe/Zurich:20161130T131500 SUMMARY:Bernoullis Tafelrunde: Mirjam Laager DESCRIPTION:Abstract [t3://file?uid=570] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161130T140000 END:VEVENT BEGIN:VEVENT UID:news540@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T081226 DTSTART;TZID=Europe/Zurich:20161124T161500 SUMMARY:Doktorkolloquium: Manuela Utzinger DESCRIPTION:An Adaptive Wavelet Method for the Solution of Boundary Integra l Equations in Three Dimensions X-ALT-DESC:An Adaptive Wavelet Method for the Solution of Boundary Integral Equations in Three Dimensions DTEND;TZID=Europe/Zurich:20161124T171500 END:VEVENT BEGIN:VEVENT UID:news432@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181217T201142 DTSTART;TZID=Europe/Zurich:20161123T141500 SUMMARY:Seminar Analysis: Luca Battaglia (University of Rome\, La Sapienza) DESCRIPTION:I will discuss the existence of groundstate solutions f or the Choquard equation in the whole space RN. I will first conside r the case of a homogeneous nonlinearity F(u) =|u|p\, then I will prove th e existence of solutions under general hypotheses. In particular\, the ca ses N=2 and N≥3 will have to be treated differently. The solutions are found through a variational mountain pass strategy. X-ALT-DESC:\nI will discuss the existence of groundstate solutions for the Choquard equation in the whole space R

The main part deals with similar features and questions about hyperbolic volume of (non-)arithmet ic Coxeter orbifolds of higher dimensions. We discuss the volume problem for certain Coxeter pyramids. This family gives rise to interesting (non- )arithmetic reflection groups whose commensurability classification has r ecently been performed (joint work with R. Guglielmetti and M. Jacquemet) .

This is a report about ongoing work. DTEND;TZID=Europe/Zurich:20161111T120000 END:VEVENT BEGIN:VEVENT UID:news162@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182114 DTSTART;TZID=Europe/Zurich:20161109T121500 SUMMARY:Bernoullis Tafelrunde: Adrian Denz DESCRIPTION:Abstract [t3://file?uid=562] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161109T130000 END:VEVENT BEGIN:VEVENT UID:news236@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T204738 DTSTART;TZID=Europe/Zurich:20161104T110000 SUMMARY:Seminar in Numerical Analysis: Thorsten Hohage (Universität Götti ngen) DESCRIPTION:Inverse problems usually consist in finding causes for observed effects. The essential difficulty in solving inverse problems is ill-po sedness: causes typically do not depend continuously on their effects alt hough vice versa effects typically depend continuously on causes. To avoi d infinite amplification of measurement errors\, regularization methods h ave to be employed to solve inverse problems numerically. The aim of regu larization theory is to analyze the convergence and speed of convergence of such methods as the noise level tends to 0.\\r\\nOver the last years V ariational Source Conditions (VSCs) have become a standard assumption for the analysis of these methods. Compared to spectral source conditions th ey have a number of advantages: They can be used for general nonquadratic penalty and data fidelity terms\, lead to simpler proofs\, are often not only sufficient\, but even necessary for certain convergence rates\, and they do not involve the derivative of the forward operator (and hence do not require restrictive assumptions such as a tangential cone condition) . However\, so far only few sufficient conditions for VSCs for specific i nverse problems are known.\\r\\nTo overcome this drawback\, we propose a g eneral strategy for the verification of VSCs\, which consists of two suff icient conditions: One of them describes the smoothness of the solution\, and the other one the degree of ill-posedness of the operator. For a num ber of important linear inverse problems this leads to equivalent charact erizations of VSCs in terms of Besov spaces and necessary and sufficient conditions for rates of convergence. We also discuss the application of o ur strategy to nonlinear parameter identification and inverse medium sca ttering problems where it provides sufficient conditions for VSCs in term s of standard function spaces. X-ALT-DESC:Inverse problems usually consist in finding causes for observed effects. The essential difficulty in solving inverse problems is ill-pos edness: causes typically do not depend continuously on their effects alth ough vice versa effects typically depend continuously on causes. To avoid infinite amplification of measurement errors\, regularization methods ha ve to be employed to solve inverse problems numerically. The aim of regul arization theory is to analyze the convergence and speed of convergence o f such methods as the noise level tends to 0.\nOver the last years Variat ional Source Conditions (VSCs) have become a standard assumption for the analysis of these methods. Compared to spectral source conditions they ha ve a number of advantages: They can be used for general nonquadratic pena lty and data fidelity terms\, lead to simpler proofs\, are often not only sufficient\, but even necessary for certain convergence rates\, and they do not involve the derivative of the forward operator (and hence do not require restrictive assumptions such as a tangential cone condition). How ever\, so far only few sufficient conditions for VSCs for specific invers e problems are known.\nTo overcome this drawback\, we propose a general st rategy for the verification of VSCs\, which consists of two sufficient co nditions: One of them describes the smoothness of the solution\, and the other one the degree of ill-posedness of the operator. For a number of im portant linear inverse problems this leads to equivalent characterization s of VSCs in terms of Besov spaces and necessary and sufficient condition s for rates of convergence. We also discuss the application of our strat egy to nonlinear parameter identification and inverse medium scattering p roblems where it provides sufficient conditions for VSCs in terms of stan dard function spaces. DTEND;TZID=Europe/Zurich:20161104T120000 END:VEVENT BEGIN:VEVENT UID:news666@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225159 DTSTART;TZID=Europe/Zurich:20161104T103000 SUMMARY:Seminar Algebra and Geometry: Diletta Martinelli (University of Edi nburgh) DESCRIPTION:Finding minimal models is the first step in the birational cla ssification of smooth projective varieties. After it is established that a minimal model exists\, some natural question arise\, such as: is the mi nimal model unique? If not\, how many are they? After recalling all the n ecessary notions of the Minimal Model Program\, I will explain that varie ties of general type admit a finite number of minimal models. I will talk about a recent joint project with Stefan Schreieder and Luca Tasin\, whe re we prove that in the case of threefold this number is bounded by a con stant depending only on the Betti numbers. I will also show that in some cases it is possible to compute this constant explicitly. X-ALT-DESC: Finding minimal models is the first step in the birational cla ssification of smooth projective varieties. After it is established that a minimal model exists\, some natural question arise\, such as: is the mi nimal model unique? If not\, how many are they? After recalling all the n ecessary notions of the Minimal Model Program\, I will explain that varie ties of general type admit a finite number of minimal models. I will talk about a recent joint project with Stefan Schreieder and Luca Tasin\, whe re we prove that in the case of threefold this number is bounded by a con stant depending only on the Betti numbers. I will also show that in some cases it is possible to compute this constant explicitly. DTEND;TZID=Europe/Zurich:20161104T120000 END:VEVENT BEGIN:VEVENT UID:news161@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182122 DTSTART;TZID=Europe/Zurich:20161103T121500 SUMMARY:Bernoullis Tafelrunde: Gabriel Dill DESCRIPTION:Abstract [t3://file?uid=564] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161103T130000 END:VEVENT BEGIN:VEVENT UID:news237@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T204932 DTSTART;TZID=Europe/Zurich:20161021T110000 SUMMARY:Seminar in Numerical Analysis: Steffen Börm (Universität Kiel) DESCRIPTION:In the context of stochastic partial differential equation\, we are frequently faced with equations in high-dimensional domains. In orde r to obtain efficient numerical methods for these equations\, we have to take local regularity properties of the solution into account\, e.g.\, by using locally refined finite element meshes. Extending standard meshing algorithms to higher dimensions poses a significant challenge.\\r\\nWe pr opose an alternative: the Galerkin trial space is constructed using a par tition of unity. By multiplying local cut-off functions with polynomials\ , we can obtain discretizations of arbitrary order\, and local grid refin ement can be realized by reducing the supports of the cut-off functions. The main challenge lies in the construction of the corresponding system m atrix\, since even determining the sparsity pattern involves interactions between cut-off functions on different levels of the mesh hierarchy.\\r\ \nOur approach leads to a sparse system matrix\, the basis functions are convenient tensor products of functions on lower-dimensional domains\, an d local regularity can be exploited by variable-order interpolation in or der to obtain close to optimal complexity. X-ALT-DESC:In the context of stochastic partial differential equation\, we are frequently faced with equations in high-dimensional domains. In order to obtain efficient numerical methods for these equations\, we have to t ake local regularity properties of the solution into account\, e.g.\, by using locally refined finite element meshes. Extending standard meshing algorithms to higher dimensions poses a significant challenge.\nWe propose an alternative: the Galerkin trial space is constructed using a partitio n of unity. By multiplying local cut-off functions with polynomials\, we can obtain discretizations of arbitrary order\, and local grid refinement can be realized by reducing the supports of the cut-off functions. The m ain challenge lies in the construction of the corresponding system matrix \, since even determining the sparsity pattern involves interactions betw een cut-off functions on different levels of the mesh hierarchy.\nOur app roach leads to a sparse system matrix\, the basis functions are convenien t tensor products of functions on lower-dimensional domains\, and local r egularity can be exploited by variable-order interpolation in order to ob tain close to optimal complexity. DTEND;TZID=Europe/Zurich:20161021T120000 END:VEVENT BEGIN:VEVENT UID:news665@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225215 DTSTART;TZID=Europe/Zurich:20161021T103000 SUMMARY:Seminar Algebra and Geometry: Jesus Martinez (MPIM Bonn) DESCRIPTION:We study variations of GIT quotients of log pairs (X\,D) where X is a hypersurface of some fixed degree and D is a hyperplane section. G IT is known to provide a finite number of possible compactifications of s uch pairs\, depending on one parameter. Any two such compactifications ar e related by birational transformations. We describe an algorithm to stud y the stability of the Hilbert scheme of these pairs\, and apply our alg orithm to the case of cubic surfaces. Finally\, we relate these compactif ications to the (conjectural) moduli space of logK-semistable pairs showi ng that any log K-stable pair is an element of our moduli and that there is a canonically defined CM line bundle that polarizes our moduli. This i s a joint work with Patricio Gallardo (University of Georgia) and Cristia no Spotti (Aarhus University). X-ALT-DESC: We study variations of GIT quotients of log pairs (X\,D) where X is a hypersurface of some fixed degree and D is a hyperplane section. G IT is known to provide a finite number of possible compactifications of s uch pairs\, depending on one parameter. Any two such compactifications ar e related by birational transformations. We describe an algorithm to stud y the stability of the Hilbert scheme of these pairs\, and apply our alg orithm to the case of cubic surfaces. Finally\, we relate these compactif ications to the (conjectural) moduli space of logK-semistable pairs showi ng that any log K-stable pair is an element of our moduli and that there is a canonically defined CM line bundle that polarizes our moduli. This i s a joint work with Patricio Gallardo (University of Georgia) and Cristia no Spotti (Aarhus University). DTEND;TZID=Europe/Zurich:20161021T120000 END:VEVENT BEGIN:VEVENT UID:news542@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T082030 DTSTART;TZID=Europe/Zurich:20161020T171500 SUMMARY:DMI Kolloquium: Marcus Grote und Thomas Vetter DTEND;TZID=Europe/Zurich:20161020T181500 END:VEVENT BEGIN:VEVENT UID:news160@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182132 DTSTART;TZID=Europe/Zurich:20161019T121500 SUMMARY:Bernoullis Tafelrunde: Lars Bugiera DESCRIPTION:Abstract [t3://file?uid=567] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161019T130000 END:VEVENT BEGIN:VEVENT UID:news664@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225229 DTSTART;TZID=Europe/Zurich:20161014T103000 SUMMARY:Seminar Algebra and Geometry: Stefano Urbinati (Padova) DESCRIPTION:Given a Mori Dream Space X we construct via tropicalization a m odel dominating all the small Q-factorial modifications. Via this constr uction we recover a Minkowski bases for the Newton-Okunkov bodies on X an d hence the movable cone for X.This is a work in progress with Elisa Posti nghel. X-ALT-DESC: Given a Mori Dream Space X we construct via tropicalization a m odel dominating all the small Q-factorial modifications. Via this constr uction we recover a Minkowski bases for the Newton-Okunkov bodies on X an d hence the movable cone for X.

This is a work in progress with Elisa Postinghel. DTEND;TZID=Europe/Zurich:20161014T120000 END:VEVENT BEGIN:VEVENT UID:news159@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182142 DTSTART;TZID=Europe/Zurich:20161012T121500 SUMMARY:Bernoullis Tafelrunde: Cristina Landolina DESCRIPTION:Abstract [t3://file?uid=563] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161012T130000 END:VEVENT BEGIN:VEVENT UID:news238@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T205111 DTSTART;TZID=Europe/Zurich:20161007T110000 SUMMARY:Seminar in Numerical Analysis: Fabio Baruffa (Leibniz-Rechenzentrum \, München) DESCRIPTION:In the framework of the Intel Parallel Computing Centre at Leib niz Supercomputing Centre (LRZ)\, Fabio Baruffa will present recent resul ts on the performance optimization of Gadget-3 on multi and many-core co mputer architectures\, including the new Intel Xeon Phi processor of seco nd generation\, codenamed Knights Landing (KNL). An overview of results f or node-level scalability\, vector efficiency and performance are present ed here. Our work is based on an isolated\, representative code kernel\, where threading parallelism\, data locality and vectorization efficiency was improved. The node-level parallel efficiency improved by factors rang ing from 5x to 16x on Haswell and KNL nodes\, respectively. Moreover\, a vectorization efficiency of 80% (6.6x) on a prototypical target loop of t he code is obtained without programming using intrinsics instructions. X-ALT-DESC:In the framework of the Intel Parallel Computing Centre at Leibn iz Supercomputing Centre (LRZ)\, Fabio Baruffa will present recent result s on the performance optimization of Gadget-3 on multi and many-core com puter architectures\, including the new Intel Xeon Phi processor of secon d generation\, codenamed Knights Landing (KNL). An overview of results fo r node-level scalability\, vector efficiency and performance are presente d here. Our work is based on an isolated\, representative code kernel\, w here threading parallelism\, data locality and vectorization efficiency w as improved. The node-level parallel efficiency improved by factors rangi ng from 5x to 16x on Haswell and KNL nodes\, respectively. Moreover\, a v ectorization efficiency of 80% (6.6x) on a prototypical target loop of th e code is obtained without programming using intrinsics instructions. DTEND;TZID=Europe/Zurich:20161007T120000 END:VEVENT BEGIN:VEVENT UID:news663@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225243 DTSTART;TZID=Europe/Zurich:20161007T103000 SUMMARY:Seminar Algebra and Geometry: Hannah Bergner (Freiburg) DESCRIPTION:Let J be a (complex) semi-simple Jordan algebra\, and consider the diagonal action of its automorphism group on the n-fold product of J. In this talk\, geometric properties of this action are studied. In parti cular\, a characterization of the closed orbits is given\, which is simil ar to the description in the case where a reductive linear algebraic grou p acts on (the n-fold product of) its Lie algebra. X-ALT-DESC: Let J be a (complex) semi-simple Jordan algebra\, and consider the diagonal action of its automorphism group on the n-fold product of J. In this talk\, geometric properties of this action are studied. In parti cular\, a characterization of the closed orbits is given\, which is simil ar to the description in the case where a reductive linear algebraic grou p acts on (the n-fold product of) its Lie algebra. DTEND;TZID=Europe/Zurich:20161007T120000 END:VEVENT BEGIN:VEVENT UID:news543@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T082159 DTSTART;TZID=Europe/Zurich:20161006T161500 SUMMARY:Doktorkolloquium: Uri Nahum DTEND;TZID=Europe/Zurich:20161006T171500 END:VEVENT BEGIN:VEVENT UID:news158@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182151 DTSTART;TZID=Europe/Zurich:20161005T121500 SUMMARY:Bernoullis Tafelrunde: Mattias Hemmig DESCRIPTION:Abstract [t3://file?uid=568] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20161005T130000 END:VEVENT BEGIN:VEVENT UID:news662@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225255 DTSTART;TZID=Europe/Zurich:20160930T103000 SUMMARY:Seminar Algebra and Geometry: Hanspeter Kraft (Basel) DESCRIPTION:The aim is to give a modern proof of the famous Theorem of A. W eil showing that for every rational action of an algebraic group G on a variety X there is a regular action of G on a variety Y and a G-equivar iant birational map X → Y. As a guideline we use an approach given by D. Zaitsev (J. Lie Theory 5\, 1995). X-ALT-DESC: The aim is to give a modern proof of the famous Theorem of A. W eil showing that for every rational action of an algebraic group G on a variety X there is a regular action of G on a variety Y and a G-equivar iant birational map X \;→ Y. As a guideline we use an approach giv en by D. Zaitsev (J. Lie Theory 5\, 1995). DTEND;TZID=Europe/Zurich:20160930T120000 END:VEVENT BEGIN:VEVENT UID:news157@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182200 DTSTART;TZID=Europe/Zurich:20160928T121500 SUMMARY:Bernoullis Tafelrunde: Nguyen-Bac Dang DESCRIPTION:Abstract [t3://file?uid=571] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20160928T130000 END:VEVENT BEGIN:VEVENT UID:news661@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225309 DTSTART;TZID=Europe/Zurich:20160923T103000 SUMMARY:Seminar Algebra and Geometry: Hanspeter Kraft (Basel) DESCRIPTION:The aim is to give a modern proof of the famous Theorem of A. W eil showing that for every rational action of an algebraic group G on a variety X there is a regular action of G on a variety Y and a G-equivarian t birational map X → Y. As a guideline we use an approach given by D. Zaitsev (J. Lie Theory 5\, 1995). X-ALT-DESC: The aim is to give a modern proof of the famous Theorem of A. W eil showing that for every rational action of an algebraic group G on a variety X there is a regular action of G on a variety Y and a G-equivarian t birational map X \;→ Y. As a guideline we use an approach given b y D. Zaitsev (J. Lie Theory 5\, 1995). DTEND;TZID=Europe/Zurich:20160923T120000 END:VEVENT BEGIN:VEVENT UID:news544@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T082442 DTSTART;TZID=Europe/Zurich:20160912T170000 SUMMARY:KOLLOQUIUM: Hanspeter Kraft DTEND;TZID=Europe/Zurich:20160912T180000 END:VEVENT BEGIN:VEVENT UID:news545@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T082623 DTSTART;TZID=Europe/Zurich:20160908T161500 SUMMARY:Doktorkolloquium: Susanna Zimmermann DTEND;TZID=Europe/Zurich:20160908T171500 END:VEVENT BEGIN:VEVENT UID:news147@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182210 DTSTART;TZID=Europe/Zurich:20160602T122000 SUMMARY:Bernoullis Tafelrunde: Uri Nahum DTEND;TZID=Europe/Zurich:20160602T130500 END:VEVENT BEGIN:VEVENT UID:news683@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225424 DTSTART;TZID=Europe/Zurich:20160602T103000 SUMMARY:Seminar Algebra and Geometry: Anne Lonjou (Toulouse) DESCRIPTION:In this talk\, we will study a 2-dimensional simplicial complex on which the Cremona group acts. After defining this complex introduced by Wright in 1992\, we will see some of its properties. Then\, we will di scuss about some work in progress aimed at showing that this complex is G romov hyperbolic. X-ALT-DESC:In this talk\, we will study a 2-dimensional simplicial complex on which \;the Cremona group acts. After defining this complex introdu ced by Wright \;in 1992\, we will see some of its properties. Then\, w e will discuss about \;some work in progress aimed at showing that thi s complex is Gromov hyperbolic. DTEND;TZID=Europe/Zurich:20160602T120000 END:VEVENT BEGIN:VEVENT UID:news445@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181219T172051 DTSTART;TZID=Europe/Zurich:20160601T141500 SUMMARY:Seminar Analysis: Paolo Bonicatto (SISSA Trieste) DESCRIPTION:Given a bounded\, autonomous vector field b: R2 → R2\, we stu dy the uniqueness of bounded solutions to the initial value problem for th e related transport equation \\r\\n(1) ∂tu + b · ∇u = 0. \\r\\nWe prove that uniqueness of weak solutions holds under the assumptions that b is of class BV and it is nearly incompressible. Our proof is based on a s plitting technique (introduced previously by Alberti\, Bianchini and Cripp a) that allows to reduce (1) to a family of 1-dimensional equations which can be solved explicitly\, thus yielding uniqueness for the original probl em. \\r\\nIn order to perform this program\, we use Disintegration Theorem and known results on the structure of level sets of Lipschitz maps: this is done after a suitable localization of the problem\, in which we exploit also Ambrosio’s superposition principle. \\r\\n \\r\\nThis is joint work with S. Bianchini and N. A. Gusev. X-ALT-DESC:\nGiven a bounded\, autonomous vector field b: R

This is a joint work with Charles M. Elliott (University of Warwick\, UK)\ , Ralf Kornhuber (Free University Berlin\, Germany) and Thomas Ranner (Uni versity of Leeds\, UK). DTEND;TZID=Europe/Zurich:20160527T120000 END:VEVENT BEGIN:VEVENT UID:news682@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225437 DTSTART;TZID=Europe/Zurich:20160527T103000 SUMMARY:Seminar Algebra and Geometry: Tatiana Bandman (Bar Ilan) DESCRIPTION:A group G is called Jordan if there is a positive integer J = JG such that every nite subgroup B of G contains a commutative subgroup A c B such that A is normal in B and the index [B : A ] <= J . There is no example of an algebraic variety with the non-Jordan au tomorphism group. It is known that the group of birational automorphisms B ir(X ) of a projective variety X is Jordan if it is not uniruled and is not Jordan if X is birational to the direct product of a projective spac e with an abelian variety. I will give an introduction to the topic and di scuss the case when variety X is a conic bundle over a non-uniruled vari ety Y and is not birational to Y x P^1: This is a joint work with Y. Zarhin. X-ALT-DESC: A group G \; is called Jordan \; if there is a positive integer J \; = JG \; \;such that every nite subgroup B \; of G \; contains a commutative subgroup A c \;B \; such that A \; is normal in B \; and the index [B \; : A ]<\;= \;J . There is no example of an algebraic variety with the non-Jordan automor phism group. It is known that the group of birational automorphisms Bir(X ) of a projective variety X \; is Jordan if it is not uniruled and is not Jordan if X \; is birational to the direct product of a projective space with an abelian variety. I will give an introduction to the topic a nd discuss the case when variety X \; is a conic bundle over a non-uni ruled variety Y \; and is not birational to Y x \;

In pa rticular\, we derive an example of a surface with infinite discrete automo rphism group. DTEND;TZID=Europe/Zurich:20160310T120000 END:VEVENT BEGIN:VEVENT UID:news439@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181219T170101 DTSTART;TZID=Europe/Zurich:20160309T141500 SUMMARY:Seminar Analysis: Christian Zillinger (Universität Bonn) DESCRIPTION:The Euler equations of fluid dynamics are time-reversible equat ions and possess many conserved quantities\, including the kinetic energy and entropy. Furthermore\, as shown by Arnold\, they even have the structu re of an infinite-dimensional Hamiltonian system. Despite these facts\, in experiments one observes a damping phenomenon for small velocity perturba tions to monotone shear flows\, where the perturbations decay with algebra ic rates. In this talk\, I discuss the underlying phase-mixing mechanism o f linear inviscid damping\, its mathematical challenges and how to establi sh decay with optimal rates for a general class of monotone shear flows. H ere\, a particular focus will be on the setting of a channel with impermea ble walls\, where boundary effects asymptotically result in the formation of singularities. X-ALT-DESC:\nThe Euler equations of fluid dynamics are time-reversible equa tions and possess many conserved quantities\, including the kinetic energy and entropy. Furthermore\, as shown by Arnold\, they even have the struct ure of an infinite-dimensional Hamiltonian system. Despite these facts\, i n experiments one observes a damping phenomenon for small velocity perturb ations to monotone shear flows\, where the perturbations decay with algebr aic rates. In this talk\, I discuss the underlying phase-mixing mechanism of linear inviscid damping\, its mathematical challenges and how to establ ish decay with optimal rates for a general class of monotone shear flows. Here\, a particular focus will be on the setting of a channel with imperme able walls\, where boundary effects asymptotically result in the formation of singularities. \; DTEND;TZID=Europe/Zurich:20160309T151500 END:VEVENT BEGIN:VEVENT UID:news674@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225629 DTSTART;TZID=Europe/Zurich:20160308T140000 SUMMARY:Seminar Algebra and Geometry: De-Qi Zhang (Singapore) DESCRIPTION:We will report our recent results on solvable groups G of autom orphisms of normal projective varieties X. One machinery we use is the e quivariant minimal model program. One purpose is to know more geometry of X from the existence of such G acting on X. X-ALT-DESC: We will report our recent results on solvable groups G of autom orphisms of normal projective varieties X. One machinery we use is the e quivariant minimal model program. One purpose is to know more geometry of X from the existence of such G acting on X. DTEND;TZID=Europe/Zurich:20160308T150000 END:VEVENT BEGIN:VEVENT UID:news550@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190114T100417 DTSTART;TZID=Europe/Zurich:20160303T171500 SUMMARY:DMI Kolloquium: Enno Lenzmann und Christian Tschudin DESCRIPTION:“Breaking Bad with Nonlocality“ & “Private Index Lookup – fetching data without revealing what is retrieved” X-ALT-DESC:“Breaking Bad with Nonlocality“ & “Private Index Lookup – fetching data without revealing what is retrieved” DTEND;TZID=Europe/Zurich:20160303T181500 END:VEVENT BEGIN:VEVENT UID:news142@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182301 DTSTART;TZID=Europe/Zurich:20160303T121500 SUMMARY:Bernoullis Tafelrunde: Fabian Müller DESCRIPTION:Abstract [t3://file?uid=558] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20160303T130000 END:VEVENT BEGIN:VEVENT UID:news673@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225652 DTSTART;TZID=Europe/Zurich:20160303T103000 SUMMARY:Seminar Algebra and Geometry: Hamid Ahmadinezhad (Bristol) DESCRIPTION:I will give an overview of the geometry of Fano 3-folds after M ori theory. After discussing past approaches to the classification\, I wi ll highlight why such attempts seem hopeless. Building on recent advances in the geometry of Fanos\, I introduce a new viewpoint on the classific ation problem. A main emphasis will be given to the unpredicted behaviour of the first examples of non-complete intersection Fanos\, discovered in a joint work with Takuzo Okada. X-ALT-DESC: I will give an overview of the geometry of Fano 3-folds after M ori theory. After discussing past approaches to the classification\, I wi ll highlight why such attempts seem hopeless. Building on recent advances in the geometry of Fanos\, I introduce a new viewpoint on the classific ation problem. A main emphasis will be given to the unpredicted behaviour of the first examples of non-complete intersection Fanos\, discovered in a joint work with Takuzo Okada. DTEND;TZID=Europe/Zurich:20160303T120000 END:VEVENT BEGIN:VEVENT UID:news672@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T225702 DTSTART;TZID=Europe/Zurich:20160226T103000 SUMMARY:Seminar Algebra and Geometry: Alvaro Liendo (Talca) DESCRIPTION:This is a joint work with A. Dubouloz.In this talk we present s ome recent results about additive group actions on non-necessarily affine algebraic varieties that generalize the usual description of additive g roup actions on affine varieties via locally nilpotent derivations. In pa rticular\, we provide a characterization of additive group actions on a w ide class of algebraic varieties in terms of a certain type of integrable vector fields. X-ALT-DESC: This is a joint work with A. Dubouloz.

In this talk we pre sent some recent results about additive group actions on non-necessarily affine algebraic varieties that generalize the usual description of addit ive group actions on affine varieties via locally nilpotent derivations. In particular\, we provide a characterization of additive group actions o n a wide class of algebraic varieties in terms of a certain type of inte grable vector fields. DTEND;TZID=Europe/Zurich:20160226T120000 END:VEVENT BEGIN:VEVENT UID:news438@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181219T165527 DTSTART;TZID=Europe/Zurich:20160224T141500 SUMMARY:Seminar Analysis: Simon Blatt (Universität Salzburg) DESCRIPTION:While the Willmore energy is invariant under Möbius transforma tions\, its negative L2-gradient flow is not - simply because the L2-scala r product used in its definition does not have this invariance. In this ta lk we present Möbius invariant versions of the Willmore flow picking up i deas of Ruben Jakob and Oded Schramm. We will discuss its uses and limitat ions and prove well-posedness of the Cauchy problem and attractivity of lo cal minimizers. X-ALT-DESC:\nWhile the Willmore energy is invariant under Möbius transform ations\, its negative L

In the particular case of homography grou ps\, we will give in this talk an overview of some results about this topi c involving transvectants\, modular forms and Rankin-Cohen brackets. DTEND;TZID=Europe/Zurich:20160205T110000 END:VEVENT BEGIN:VEVENT UID:news141@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181113T182308 DTSTART;TZID=Europe/Zurich:20151217T121500 SUMMARY:Bernoullis Tafelrunde: Monica Bugeanu DESCRIPTION:Abstract [t3://file?uid=555] X-ALT-DESC:Abstract DTEND;TZID=Europe/Zurich:20151217T130000 END:VEVENT BEGIN:VEVENT UID:news457@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181227T175842 DTSTART;TZID=Europe/Zurich:20151216T141500 SUMMARY:Seminar Analysis: Alessandra Pluda ( Università di Pisa) DESCRIPTION:I consider the motion by curvature of a network of curves in th e Euclidean plane and I discuss existence\, uniqueness\, and asymptotic be havior of the evolution. In particular\, I focus on two model cases: a r egular embedded network composed by three curves with fixed endpoints (tri od) and a regular embedded network composed by two curves\, one of which i s closed (spoon). After talking about the state of art of the problem\, I will present some new and possibly ”incoming” results obtained with C arlo Mantegazza and Matteo Novaga. X-ALT-DESC:\nI consider the motion by curvature of a network of curves in t he Euclidean plane and I discuss existence\, uniqueness\, and asymptotic b ehavior of the evolution. In particular\, I focus on two model cases: a regular embedded network composed by three curves with fixed endpoints (tr iod) and a regular embedded network composed by two curves\, one of which is closed (spoon). After talking about the state of art of the problem\, I will present some new and possibly ”incoming” results obtained with Carlo Mantegazza and Matteo Novaga. DTEND;TZID=Europe/Zurich:20151216T151500 END:VEVENT BEGIN:VEVENT UID:news694@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T230240 DTSTART;TZID=Europe/Zurich:20151211T103000 SUMMARY:Seminar Algebra and Geometry: Federico Lo Bianco (Rennes) DESCRIPTION:An automorphism f acting on a complex projective (or\, more ge nerally\, compact Kaehler) manifold X induces by pull-back a linear isomo rphism f* of the cohomology of X. The study of the possible isomorphisms that can be realized this way is interesting per se and also has importan t applications in the study of the dynamics of f: for example\, the topol ogical entropy of f\, measuring the chaos created by repeatedly applying f\, can be recovered from the eigenvalues of f*. If X is a surface the si tuation is well understood: if f* is not of finite order\, then either it is virtually unipotent with only one non-trivial Jordan block of dimensi on 3\, or semi-simple with only two eigenvalues with module different tha n 1. I will present the similar results I obtained with Cantat for threef olds and show their optimality with examples on complex tori. X-ALT-DESC: An automorphism f acting on a complex projective (or\, more ge nerally\, compact Kaehler) manifold X induces by pull-back a linear isomo rphism f

(Joint with Jack Jeffries) DTEND;TZID=Europe/Zurich:20151113T120000 END:VEVENT BEGIN:VEVENT UID:news452@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20181227T172253 DTSTART;TZID=Europe/Zurich:20151111T141500 SUMMARY:Seminar Analysis: Zoltán Balogh (Universität Bern) DESCRIPTION:A pair of metric spaces (X\;Y) is said to have the Lipschitz ex tension property if any Lipschitz map from a subset of X into Y can be ext ended to a globally defined Lipschitz map to the whole space X. In this t alk I will first recall some classical extension results for spaces with a linear structure\, and I will present recent results for the case when th e target space Y is the Heisenberg group. X-ALT-DESC:\nA pair of metric spaces (X\;Y) is said to have the Lipschitz e xtension property if any Lipschitz map from a subset of X into Y can be ex tended to a globally defined Lipschitz map to the whole space X. In this talk I will first recall some classical extension results for spaces with a linear structure\, and I will present recent results for the case when t he target space Y is the Heisenberg group. DTEND;TZID=Europe/Zurich:20151111T151500 END:VEVENT BEGIN:VEVENT UID:news245@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20180716T211238 DTSTART;TZID=Europe/Zurich:20151106T110000 SUMMARY:Seminar in Numerical Analysis: Sanna Mönkölä (University of Jyv äskylä) DESCRIPTION:A wide range of numerical methods have been used for solving t ime-harmonic wave equations. Typically\, the methods are based on complex -valued formulations leading to large-scale indefinite linear equations. An alternative is to simulate time-dependent equations in time\, until th e time-harmonic solution is reached. However\, this approach suffers from poor convergence\, particularly in the case of large wavenumbers and com plicated domains. We accelerate the convergence rate by employing a contr ollability method. The problem is formulated as a least-squares optimizat ion problem\, which is solved by the conjugate gradient algorithm. The ef ficiency of the method relies on smart discretizations. For spatial discr etization we use the spectral element method or the discrete exterior cal culus\, and for time evolution we consider leap-frog style discretization with non-uniform timesteps or higher-order schemes. For constructing spa tially isotropic grids for complex geometries\, we use non-uniform polygo nal structures imitating the close packing in crystal lattices. X-ALT-DESC:A wide range of numerical methods have been used for solving ti me-harmonic wave equations. Typically\, the methods are based on complex- valued formulations leading to large-scale indefinite linear equations. A n alternative is to simulate time-dependent equations in time\, until the time-harmonic solution is reached. However\, this approach suffers from poor convergence\, particularly in the case of large wavenumbers and comp licated domains. We accelerate the convergence rate by employing a contro llability method. The problem is formulated as a least-squares optimizati on problem\, which is solved by the conjugate gradient algorithm. The eff iciency of the method relies on smart discretizations. For spatial discre tization we use the spectral element method or the discrete exterior calc ulus\, and for time evolution we consider leap-frog style discretization with non-uniform timesteps or higher-order schemes. For constructing spat ially isotropic grids for complex geometries\, we use non-uniform polygon al structures imitating the close packing in crystal lattices. DTEND;TZID=Europe/Zurich:20151106T120000 END:VEVENT BEGIN:VEVENT UID:news691@dmi.unibas.ch DTSTAMP;TZID=Europe/Zurich:20190212T230316 DTSTART;TZID=Europe/Zurich:20151106T103000 SUMMARY:Seminar Algebra and Geometry: Elisa Gorla (Neuchâtel) DESCRIPTION:In this talk I will discuss a new idea for studying initial id eals and generic initial ideals of ideals in a polynomial ring graded ove r Zm. \\r\\nThese ideas will then be applied to the study of universal Gr oebner bases of ideals of minors\, which admit such a grading. The main t ools and concepts are Zm gradings\, multigraded Hilbert series\, universa l Groebner bases\, initial and generic initial ideals. I will introduce a nd study two families of multigraded ideals with the property that any tw o ideals in the same family that have the same Hilbert series also have the same generic initial ideal. I will show that ideals of minors belong to one of these families\, and derive some result about their universal G roebner bases. X-ALT-DESC: In this talk I will discuss a new idea for studying initial id eals and generic initial ideals of ideals in a polynomial ring graded ove r Z