Upcoming Events

Due to infection prevention measures, participation in events at the institute is presently not possible for guests.

Many events are currently organized online. Information on how to access these events can be found by clicking “more” below the respective entry.


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Tuesday, 01.12.2020, 15:00 (Online Event)
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Roman Kravchenko, Humboldt-Universität zu Berlin:
Distributed optimization with quantization for computing Wasserstein barycenters
more ... Location
Online Event

Further Informations
Dieser Vortrag findet bei Zoom statt: https://zoom.us/j/492088715

Host
WIAS Berlin
Tuesday, 01.12.2020, 15:15 (Online Event)
Oberseminar Nonlinear Dynamics
Dr. Felix Kemeth, Johns Hopkins University, USA:
2-cluster fixed-point analysis of mean-coupled Stuart--Landau oscillators in the center manifold
more ... Location
Online Event

Abstract
Clustering in phase oscillator systems with long-range interactions has been subject to theoretical investigations for many years. By mapping the dynamics of mean-coupled Stuart-Landau oscillators onto the center manifold of the Benjamin-Feir instability, we aim to add to the theoretical understanding of clustering in systems beyond phase oscillator ensembles. In particular, we discuss the formation of 2-cluster states in this lower dimensional manifold and outline the resulting implications for the dynamics of the coupled oscillator ensemble.

Host
Freie Universität Berlin
WIAS Berlin
December 2 – 3, 2020 (Online Event)
Workshop/Konferenz: ECMI Webinar “Math for Industry 4.0 - Models, Methods and Big Data”
more ... Location
Online Event

Host
WIAS Berlin
Wednesday, 02.12.2020, 10:00 (Online Event)
Forschungsseminar Mathematische Statistik
Dr. Yegor Klochkov, University of Cambridge, UK:
Robust K-means clustering under two moments
more ... Location
Online Event

Abstract
We consider the robust algorithms for the k-means clustering problem where a quantizer is constructed based on N independent observations. Our main results are median of means based non-asymptotic excess distortion bounds that hold under the two bounded moments assumption in a general separable Hilbert space. In particular, our results extend the renowned asymptotic result of Pollard(1981) who showed that the existence of two moments is sufficient for strong consistency of an empirically optimal quantizer in R^d. In a special case of clustering in R^d, under two bounded moments, we prove matching (up to constant factors) non-asymptotic upper and lower bounds on the excess distortion, which depend on the probability mass of the lightest cluster of an optimal quantizer. Our bounds have the sub-Gaussian form, and the proofs are based on the versions of uniform bounds for robust mean estimators. This is joint work with Alexei Kroshnin and Nikita Zhivotovskiy.

Further Informations
Der Vortrag findet bei Zoom statt: https://zoom.us/j/159082384

Host
Humboldt-Universität zu Berlin
WIAS Berlin
Tuesday, 08.12.2020, 15:00 (Online Event)
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. Pavel Dvurechensky, WIAS Berlin:
Accelerated alternating minimization methods
more ... Location
Online Event

Abstract
We combine alternating minimization (AM) and Nesterov-type momentum acceleration and propose a generic accelerated alternating minimization method with a $1/k^2$ convergence rate in terms of the objective for convex problems and $1/k$ in terms of the squared gradient norm for non-convex problems, where $k$ is the iteration counter. Our method does not require any knowledge of neither convexity of the problem nor function parameters such as smoothness constant, i.e. it is adaptive to convexity and smoothness. Further, we develop its primal-dual modification for convex problems with linear constraints. We consider two applications of our methods to highlight their properties. The first one is the non-convex collaborative filtering problem, and the second one is optimal transport, where our primal-dual method takes a form of accelerated Sinkhorn's algorithm or accelerated Iterative Bregman Projections algorithm. In both applications, we show numerically that our methods outperform the baselines. In the second application, we also obtain state-of-the-art complexity results for optimal transport problems.

Further Informations
Dieser Vortrag findet bei Zoom statt: https://zoom.us/j/492088715

Host
WIAS Berlin
Wednesday, 09.12.2020, 11:30 (Online Event)
Seminar Interacting Random Systems
Robert Patterson:
tba
more ... Location
Online Event

Further Informations
Seminar Interacting Random Systems

Host
WIAS Berlin
Wednesday, 09.12.2020, 15:15 (Online Event)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Grigor Nika, WIAS Berlin:
Effective bulk-surface thermistor models for OLEDs (online talk)
more ... Location
Online Event

Abstract
We consider a thin-film OLED device placed on a flat surface, part of a bulk substrate material. The device is assumed to have N>2 layers and total thickness h>0. An effective electrothermal model is derived by considering the limit of vanishing thickness as it approaches zero under physically motivated scalings. The effective equations consist of two equations for the lateral current flow in the top and bottom electrodes and an iterative set of algebraic equations for the vertical flow in the organic layers posed on the flat surface where the OLED is placed and coupled to the heat equation in the bulk substrate material.

Further Informations
Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)

Host
WIAS Berlin
Thursday, 10.12.2020, 15:00 (Online Event)
TES-Seminar on Energy-based Mathematical Methods and Thermodynamics
Dr. Martin Kružík, Czech Academy of Sciences:
Equilibrium for multiphase solids with Eulerian interfaces (online talk)
more ... Location
Online Event

Abstract
We describe a general phase-field model for hyperelastic multiphase materials. The model features an elastic energy functional that depends on the phase-field variable and a surface energy term that depends in turn on the elastic deformation, as it measures interfaces in the deformed configuration. We prove the existence of energy minimizing equilibrium states and Gamma-convergence of diffuse-interface approximations to the sharp-interface limit. This is a joint work with D. Grandi, E. Mainini and U. Stefanelli.

Further Informations
Please register on this link: https://mathplus.de/topic-development-lab/tes-winter-2020-21/tes-seminar-on-energy-based-mathematical-methods-and-thermodynamics/

Host
Technische Universität Berlin
WIAS Berlin
Wednesday, 13.01.2021, 11:30 (Online Event)
Seminar Interacting Random Systems
Sabine Jansen, Universität München, null:
tba (online talk)
more ... Location
Online Event

Further Informations
Seminar Interacting Random Systems

Host
WIAS Berlin