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Veranstaltungen

Donnerstag, 29.01.2026, 10:00 Uhr (WIAS-ESH): Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations / Mathematical Optimization
Clemens Sirotenko, WIAS Berlin:
Learning Elliptic Variational Inequalities via Weak Min-Max Formulations
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
In this talk, we will present a novel weak adversarial framework for solving obstacle problems using neural networks. By reformulating the problem via (generalised) regularised gap functions into a natural min-max structure, we create a setting well suited to learning based approaches. We will outline the error analysis, highlighting both discretisation and statistical errors. Then, we will explain how parametrising the solution and test functions as neural networks allows us to solve the resulting min-max problem using a modified gradient descent-ascent method. Numerical experiments illustrate the robustness of the method. We will conclude by discussing current limitations, open problems, and future challenges of the approach.

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Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations

Veranstalter
WIAS Berlin
Donnerstag, 29.01.2026, 14:00 Uhr (WIAS-ESH): Seminar Numerische Mathematik
Dr. Jose Rodrigo Rojo Garcia, WIAS Berlin:
Inverse problems through the Bayesian paradigm
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
WIAS Berlin
Mittwoch, 04.02.2026, 10:00 Uhr (WIAS-ESH): Forschungsseminar Mathematische Statistik
Prof. Dr. Frank Konietschke, Charité Universitätsmedizin Berlin:
Advancing decision-efficiency in (pre)-clinical research via novel sequential frameworks
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
The escalating costs and ethical imperatives of drug development necessitate statistical frameworks that prioritize both efficiency and rigorous evidence generation. Conventional fixed-sample designs often lack the flexibility to adapt to emerging data, leading to potentially redundant animal testing or delayed decision-making. This talk introduces a suite of novel sequential testing procedures designed to optimize the transition from pre-clinical discovery to clinical validation. We explore three primary pillars of application: Pre-clinical Statistics: We demonstrate how sequential probability ratio tests (SPRT) and group sequential designs can be adapted for small-sample laboratory studies, ensuring ethical ßtop-for-efficacy" or ßtop-for-futility" boundaries are met without compromising the Type I error rate. Generalized Pairwise Comparisons (GPC): We extend the sequential framework to GPC, a versatile method for analyzing multiple prioritized endpoints. This allows researchers to assess the net clinical benefit of a treatment sequentially, integrating diverse outcomes (e.g., survival, toxicity, and biomarkers) into a single, unified decision metric. Digital Biomarkers: Addressing the high-frequency, longitudinal nature of data from wearable devices, we propose sequential monitoring techniques that detect treatment signals in real-time. These methods account for the inherent "noise" and autocorrelation in digital health data, facilitating faster "go/no-go" decisions in early-phase trials. By bridging these methodologies, this talk provides a roadmap for implementing adaptive evidence synthesis that reduces sample size requirements and accelerates the identification of promising therapeutic candidates.

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Via Zoom: https://hu-berlin.zoom-x.de/j/68089797717?pwd=ek1XRmZuYUJIL2tObTlCSzRBUXNiQT09 Meeting-ID: 680 8979 7717 Passwort: 016303

Veranstalter
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
4. – 6. Februar 2026 (WIAS-ESH): Workshop/Konferenz: Algebraic and geometric aspects of signatures and rough analysis
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
Technische Universität Berlin
WIAS Berlin
Donnerstag, 05.02.2026, 10:00 Uhr (WIAS-HVP-3.04): Forschungsseminar Mathematische Modelle der Photonik
Dr. Eduard Kuhn, WIAS Berlin:
Simulation of high power diode lasers with stacked multiple active regions and tunnel junctions
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Weierstraß-Institut, Hausvogteiplatz 11A, 10117 Berlin, 3. Etage, Raum: 3.04

Abstrakt
Many applications require diode lasers that are able to generate high output powers, for example in LiDAR (Light Detection and Ranging) systems or in future inertial confinement fusion power plants. In order to achieve high powers while maintaining low injected current densities, it is beneficial to stack multiple active regions and separate them using tunnel junctions. As the tunnel junctions are highly absorbing due to the small band gap and high doping levels, their accurate positioning in the nodes of the vertical mode is crucial. In order to answer important design questions such as the optimal distance between active regions and the tunnel junctions, a simulation tool is required. For our tool we solve the standard drift-diffusion equations augmented with additional models to describe effects such as tunneling and stimulated emission. Since the tunnel junctions are operated under reverse bias, we employ a non-local band-to-band tunneling model. This talk presents the simulation model and demonstrates its application to a multi-junction laser diode.

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Forschungsseminar Mathematische Modelle der Photonik

Veranstalter
WIAS Berlin
6. Februar 2026 (WIAS-405-406): Workshop/Konferenz: Northern-German Network on Networks
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406

Abstrakt
The aim of the symposium is to create an opportunity for researchers in network dynamical systems working in (Northern) Germany to connect, to regularly meet, and to exchange ideas. The meeting is intended to be the first in a regular series of symposia which will take place at WIAS, University of Hamburg and, potentially, also other places.

Veranstalter
WIAS Berlin
Universität Hamburg
Mittwoch, 11.02.2026, 11:30 Uhr (WIAS-406): Seminar Interacting Random Systems
Elias Zimmermann, Universität Leipzig:
Quantitative mixing properties for Gibbs fields on bounded degree graphs
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstrakt
Mixing properties are an important object of study within the theory of Gibbs measures. In this talk I will focus on two quantitative mixing properties: exponential $phi$-mixing (also called weak mixing) and exponential $psi$-mixing (also called ratio weak mixing). These mixing conditions are well studied for Gibbs fields on square lattices. For instance, the unique Gibbs state of the Ising model above the critical temperature exhibits both types of mixing. In this talk we shall consider random fields on arbitrary graphs with bounded degree. While exponential $phi$-mixing is known to hold whenever Dobrushin's uniqueness condition is satisfied, exponential $psi$-mixing has been studied very little in this general setting. The main result I'm going to present shows that for Markovian random fields $phi$-mixing with sufficiently high exponential decay rate implies $psi$-mixing with slower, but still exponential decay rate. This generalizes a result of Alexander for square lattices and allows to formulate a general criterion for exponential $psi$-mixing of Gibbs measures in terms of the corresponding Dobrushin constant. I will illustrate how this criterion applies to Ising and Potts models on regular trees.

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Seminar Interactin Random Systems

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WIAS Berlin
Mittwoch, 11.02.2026, 14:15 Uhr (WIAS-ESH): Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Andrea Poiatti, Universität Wien, Österreich:
A Navier--Stokes/Mullins--Sekerka system with different densities: Weak solutions
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
In this talk, I would like to introduce a model for the flow of two incompressible, viscous and immiscible fluids in a bounded domain, with different densities and viscosities. This model consists of a coupled system of Navier--Stokes and Mullins--Sekerka type parts, and can be obtained from the asymptotic limit of the diffuse interface model introduced by Abels, Garcke, and Grün in 2012. I will introduce a new notion of weak solutions and prove its global in time existence, together with a consistency result. This new notion of solution allows to include the case of different densities of the fluids, a sharp energy dissipation principle `a la De Giorgi, as well as a weak formulation of the constant contact angle condition at the boundary, which were left open in the previous notion of solution proposed by H. Abels and M. Röger in 2009. This is a joint project with H. Abels.

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Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
12. – 13. Februar 2026 (WIAS-ESH): Workshop/Konferenz: Widening the Scope of Rough and Stochastic Analysis -- Rough Women Reach Out!
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
Technische Universität Berlin
WIAS Berlin
2. – 4. M�rz 2026 (IHP): Workshop/Konferenz: Leibniz MMS Days 2026
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Leibniz Institute for High Performance Microelectronics Frankfurt/Oder

Veranstalter
Leibniz Institute for High Performance Microelectronics Frankfurt/Oder
WIAS Berlin
16. – 18. M�rz 2026 (WIAS-ESH): Workshop/Konferenz: Workshop Optimal Transport and Noise: OT Meets (S)PDEs
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
Technische Universität Berlin
WIAS Berlin
1. – 5. Juni 2026 (WIAS-ESH): Workshop/Konferenz: ESGI 194 - The Berlin Study Group with Industry
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
WIAS Berlin
6. – 8. Juli 2026 (WIAS-ESH): Workshop/Konferenz: Spreading Dynamics in Random Environment
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
WIAS Berlin