Upcoming Events
Many events are currently organized online. Information on how to access these events can be found by clicking “more” below the respective entry.
- Tuesday, 13.06.2023, 15:00 (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. Oleg Butkovsky, WIAS Berlin:
Stochastic sewing for weak uniqueness of SDEs and SPDEs (hybrid talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
I would like to report about very early steps of a new project. It has been thought for a while that stochastic sewing is relevant only for obtaining strong unqiueness and strong rate of convergence of numerical methods. I will try to convince you that stochastic sewing combined with the Scheutzow-Kulik generalized coupling technique allows to achieve weak uniqueness of SDEs and weak rate of convergence of Euler scheme. Work in progress with Leonid Mytnik.
Further Informations
Dieser Vortrag findet auch via Zoom statt: https://zoom.us/j/492088715
Host
WIAS Berlin
- Wednesday, 14.06.2023, 15:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Ass. Prof. Dr. Ana Leonor Silvestre, University of Lisbon, Portugal:
Optimal boundary control for the steady Navier--Stokes equations with directional do-nothing boundary conditions (hybrid talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
We consider the steady Navier--Stokes equations with mixed boundary conditions, where, instead of the classical do-nothing (CDN) outflow condition, a directional do-nothing (DDN) or a regularized directional do-nothing (RDDN) condition are imposed. An auxiliary reference flow, which will also work as a lifting of the inhomogeneous Dirichlet boundary values, is used to define the DDN and RDDN conditions. Our aim is the minimization of a cost functional of velocity tracking type by means of a control localized on the boundary. We prove the existence of a solution for this optimal control problem and, in the case of the RDDN condition, obtain the adjoint system and derive the corresponding first order optimality conditions. All results are obtained under appropriate assumptions on the size of the data and the controls, which, however, are less restrictive when compared with the case of a CDN outflow condition. This is a joint work with Pedro Nogueira and Jorge Tiago (IST, U Lisboa)
Further Informations
Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Tuesday, 20.06.2023, 14:00 (WIAS-ESH)
- Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations / Mathematical Optimization
Dr. Evelyn Herberg, Heidelberg University:
Deep learning with variable time stepping (online talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
Feature propagation in Deep Neural Networks (DNNs) can be associated to nonlinear discrete dynamical systems. The novelty, in this talk, lies in letting the discretization parameter (time step-size) vary from layer to layer, which needs to be learned, in an optimization framework. The proposed framework can be applied to any of the existing networks such as ResNet, DenseNet or Fractional-DNN. This framework is shown to help overcome the vanishing and exploding gradient issues. Stability of some of the existing continuous DNNs such as Fractional-DNN is also studied. The proposed approach is applied to an ill-posed 3D-Maxwell's equation.
Further Informations
Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations
Host
WIAS Berlin
- Tuesday, 20.06.2023, 15:00 (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. Leon Bungert, TU Berlin:
Polarized consensus based particle dynamics (hybrid talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
In this talk I will speak about a novel polarized consensus based method for optimization and sampling which relies on a kernelized weighted mean and covariance. This way the method allows for finding several global minima of non-convex functions and for multi-modal sampling. I will present numerical examples and first theoretical results on this novel method. This talk is based on recent joint work together with Tim Roith and Philipp Wacker.
Further Informations
Dieser Vortrag findet auch via Zoom statt: https://zoom.us/j/492088715
Host
WIAS Berlin
- Wednesday, 21.06.2023, 11:30 (WIAS-405-406)
- Seminar Interacting Random Systems
Sanjoy Jhawar, WIAS Berlin:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Seminar Interacting Random Systems (Hybrid Event)
Host
WIAS Berlin
- Wednesday, 21.06.2023, 13:00 (WIAS-ESH)
- Berlin Oberseminar: Optimization, Control and Inverse Problems
Dr. Leon Bungert, TU Berlin:
The geometry of adversarial machine learning
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
It is well-known that despite their aptness for complicated tasks like image classification, modern neural networks are prone to insusceptible input perturbations (a.k.a. adversarial attacks) which can lead to severe misclassifications. Adversarial training is a state-of-the-art method to train classifiers which are more robust against these adversarial attacks. The method features minimization of a robust risk and has interpretations as game-theoretic problem, distributionally robust optimization problem, dual of an optimal transport problem, or nonlocal geometric regularization problem. In this talk I will focus on the last interpretation which allows for the application of tools from calculus of variations and geometric measure theory to study existence, regularity, and asymptotic behavior of minimizers. In particular, I will show that adversarial training of binary agnostic classifiers is equivalent to a nonlocal and weighted perimeter regularization of the decision boundary. Furthermore, I will show Gamma-convergence of this perimeter to a local anisotropic perimeter as the strength of the adversary tends to zero, thereby establishing an asymptotic regularization effect of adversarial training. Lastly, I will discuss probabilistic relaxations of adversarial training which exhibit better clean accuracies and also have a perimeter-regularization interpretation.
Further Informations
Berlin Oberseminar: Optimization, Control and Inverse Problems
Host
WIAS Berlin
Technische Universität Berlin
Humboldt-Universität zu Berlin
- Wednesday, 28.06.2023, 11:30 (WIAS-405-406)
- Seminar Interacting Random Systems
Céline Kerriou, Universität zu Köln:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Seminar Interacting Random Systems (Hybrid Event)
Host
WIAS Berlin
- Wednesday, 28.06.2023, 14:00 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Peter Gladbach, Universität Bonn:
Homogenization and mean-field limits of transport costs (hybrid talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
We treat the limits, in terms of Gamma-convergence, of several discrete dynamic transport costs. The first concerns Wasserstein-type transport actions on stationary random graphs, for which we use stochastic homogenization and geometric measure theory to find a continuous limit functional. (joint work with Lorenzo Portinale and Jan Maas) The second treats interacting particles with different origins and destinations, which will develop coordinated oscillations in order to minimize a common functional. We show Gamma-convergence as the number of particles tends to infinity, and that minimizers converge to solutions of a Vlasov equation. (joint work with Bernhard Kepka)
Further Informations
Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Wednesday, 28.06.2023, 15:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Peter Lewintan, Universität Duisburg-Essen:
Optimal Korn--Maxwell--Sobolev inequalities (hybrid talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
We present a complete picture of coercive Korn-type inequalities for generalised incompatible fields, and optimally extend and unify several previously known inequalities that are crucial to the existence theory for a variety of models in continuum mechanics.
Further Informations
Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- July 3 – 5, 2023 (WIAS-ESH)
- Workshop/Konferenz: Nonlinear Dynamics in Semiconductor Lasers 2023
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik
WIAS Berlin
- Friday, 07.07.2023, 08:00 (Harnack-Haus)
- Workshop: Phase transitions in random point systems
Phase transitions in random point systems
more ... Location
Harnack-Haus -- Tagungsstätte der Max-Planck-Gesellschaft
Host
WIAS Berlin
DFG Schwerpunktprogramm 2265
- Friday, 07.07.2023, 10:00 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Edriss S. Titi, University of Cambridge:
The inviscid primitive equations and the effect of fast rotation (hybrid talk)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
Large scale dynamics of the oceans and the atmosphere are governed by the primitive equation (PE). It is well-known that the three-dimensional viscous PE is globally well-posed in Sobolev spaces. In this talk, I will discuss the ill-posedness in Sobolev spaces, the local well-posedness in the space of analytic functions, and the finite-time blowup of solutions to the three-dimensional inviscid PE (also known as the hydrostatic Euler equations) with rotation (Coriolis force). Eventually, I will also show, in the case of “well-prepared" analytic initial data, the regularizing effect of the Coriolis force by providing a lower bound for the life-span of the solutions which grows toward infinity with the rotation rate. The latter is achieved by a delicate analysis of a simple limit resonant system whose solution approximates the corresponding solution of the 3D inviscid PE with the same initial data. In addition, and if time allows I will discuss Onsager's conjecture in the context of the inviscid primitive equations.
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Wednesday, 12.07.2023, 11:30 (WIAS-405-406)
- Seminar Interacting Random Systems
Klippel, TU Darmstadt:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Seminar Interacting Random Systems (Hybrid Event)
Host
WIAS Berlin
- Monday, 17.07.2023, 09:00 (Harnack-Haus)
- SPP2265 Summer School: Probability and geometry on configuration spaces
SPP2265 Summer School: Probability and geometry on configuration spaces
more ... Location
Harnack-Haus -- Tagungsstätte der Max-Planck-Gesellschaft
Host
WIAS Berlin
DFG Schwerpunktprogramm 2265
- August 30 – September 1, 2023 (WIAS-ESH)
- Workshop/Konferenz: Workshop on Biophysics-based modeling and data assimilation in medical imaging 2023
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
WIAS Berlin
Charité - Universitätsmedizin Berlin
- September 13 – 15, 2023 (WIAS-ESH)
- Workshop/Konferenz: Energetic Methods for Multi-Component Reactive Mixtures Modelling Stability and Asymptotic Analysis
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
The central theme of this workshop are mechanical models describing the transport of mass, momentum, and energy in multi-component mixtures, including diffusion, convection, and heat transfer. A consistent account of reactions is a further concern. EMRM 2023 focuses in particular on energetic and entropic tools for strongly coupled systems of hyperbolic--parabolic type, whose analysis is still underdeveloped and has received insufficient attention relative to their tremendous significance in real-world applications. Many complex physical processes not only involve mass transfer induced by random diffusion, but also reaction processes and directed transport including non-local drifts induced, for instance, by the interaction of electrically charged particles. The relative influence of these different processes will depend on the specific application. Developing a framework that asymptotically relates the different models is nowadays an active field of research in multi-component flow modelling. This workshop focuses on the analysis of multi-component mixtures using diffusion models and hydrodynamic models, on the analysis of complex evolutionary systems of hyperbolic--parabolic type, including multi-phase problems, as well as on the connections between these approaches by means of asymptotic analysis.
Host
WIAS Berlin
Technische Universität Wien