Upcoming Events
- Wednesday, 21.01.2026, 10:00 (WIAS-HVP-3.13)
- Forschungsseminar Mathematische Statistik
Prof. Ulrike Schneider, TU Wien:
A unified framework for pattern recovery in penalized estimation
more ... Location
Weierstraß-Institut, Hausvogteiplatz 11A, 10117 Berlin, 3. Etage, Raum: 3.13
Abstract
We consider the framework of least-squares penalized estimation where the penalty term is given by a polyhedral norm, or more generally, a polyhedral gauge, which encompasses methods such as LASSO and generalized LASSO, SLOPE, OSCAR, PACS and others. Each of these estimators can uncover a different structure or pattern of the unknown parameter vector. We define a novel and general notion of patterns based on subdifferentials and formalize an approach to measure pattern complexity. For pattern recovery, we provide a minimal condition for a particular pattern to be detected with positive probability, the so-called accessibility condition. We make the connection to estimation uniqueness by showing that uniqueness holds if and only if no pattern with complexity exceeding the rank of the X-matrix is accessible. Subsequently, we introduce the noiseless recovery condition which is a stronger requirement than accessibility and which can be shown to play exactly the same role as the well-known irrepresentability condition for the LASSO in that the probability of pattern recovery is bounded by 1/2 if the condition is not satisfied. Through this, we unify and extend the irrepresentability condition to a broad class of penalized estimators using an interpretable criterion. We also look at the gap between accessibility and the noiseless recovery condition and discuss that our criteria show that it is more pronounced for simple patterns. Finally, we prove that the noiseless recovery condition can indeed be relaxed when turning to so-called thresholded penalized estimation: in this setting, the accessibility condition is already sucient (and necessary) for sure pattern recovery provided that the signal of the pattern is large enough. We demonstrate how our findings can be interpreted through a geometrical lens throughout the talk and illustrate our results for the Lasso as well as other estimation procedures. Related references: P. Graczyk, U. Schneider, T. Skalski and P. Tardivel, A Unified Framework for Pattern Recovery in Penalized and Thresholded Estimation and its Geometry; https://doi.org/10.1007/s10957-025-02863-6 U. Schneider and P. Tardivel, The Geometry of Uniqueness, Sparsity and Clustering in Penalized Estima- tion; https://jmlr.org/papers/v23/21-0420.html K. Ewald and U. Schneider, On the Distribution, Model Selection Properties and Uniqueness of the Lasso Estimator in Low and High Dimensions; https://doi.org/10.1214/20-EJS1687 --
Further Informations
Dieser Vortrag findet hybrid statt. Die Teilnahme per Zoom ist über den (neuen!) Link:
https://hu-berlin.zoom-x.de/j/64809417303?pwd=iLT5xbdDZspAcUCuLrwNnaN90ZQBpj.1
Meeting-ID: 648 0941 7303
Passwort: 258449
Host
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
- Wednesday, 21.01.2026, 11:30 (WIAS-406)
- Seminar Interacting Random Systems
Yannic Steenbeck, TU Braunschweig:
Reversible birth-and-death dynamics in continuum: Free-energy dissipation and attractor properties
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstract
The theory of Gibbs point processes, describing interacting systems of particles in continuous space, is by now a classical topic in probability and statistical mechanics and for various questions, somewhat satisfactory results have been obtained. On the lattice, these results on the equilibrium behavior of large systems of interacting particles are complemented by a detailed study of associated dynamics. In contrast, very little is known about dynamical aspects in continuum, in particular out-of-equilibrium dynamics and convergence to equilibrium. In this talk, I will review basic terms of the probabilistic theory of statistical mechanics and present our first investigation of the long-time behavior of birth-and-death dynamics in continuum space. Our main results there confirm the physical intuition that the free energy is non-increasing in time and moreover governs the long-term behavior of large systems of interacting particles.
Further Informations
Seminar Interactin Random Systems
Host
WIAS Berlin
- Wednesday, 21.01.2026, 14:15 (WIAS-405-406)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
PD Dr. Olaf Klein, WIAS Berlin:
Uncertainty quantification for a model for a magnetostrictive material involving a hysteresis operator
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Thursday, 22.01.2026, 10:30 (WIAS-Library)
- Software and Data Seminar
Laura Prieto Saavedra, WIAS Berlin:
Research software & data for applied mathematics: Principles and roadmap
more ... Location
Weierstraß-Institut, Hausvogteiplatz 5-7, 10117 Berlin, R411
Further Informations
Seminar Software and Data
Host
WIAS Berlin
- Tuesday, 27.01.2026, 15:00 (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. Oleg Butkovsky, WIAS Berlin:
Pathwise uniqueness for SDEs in Hilbert spaces
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Dieser Vortrag findet auch via Zoom statt: https://wias-berlin-de.zoom-x.de/j/69982487566
Host
WIAS Berlin
- Wednesday, 28.01.2026, 10:00 (WIAS-405-406)
- Forschungsseminar Mathematische Statistik
Prof. Jakob Runge, Universität Potsdam:
Causal inference (on time series data)
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
This talk is intended as a broad overview of graphical causal inference, including causal discovery, where the task is to learn a causal graph, and causal e?ect estimation, where a causal graph is already assumed and the task is to quantify causal e?ects. In both cases a focus will be on statistically robust estimation strategies, including a theoretical optimality result for adjustment-based causal eect estimation. I will also illustrate practical work?ows in my software package Tigramite.
Host
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
- Wednesday, 28.01.2026, 14:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Anastasija Pešić, WIAS Berlin:
Curvature-driven pattern formation in biomembranes: A gradient flow approach
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Wednesday, 28.01.2026, 16:15 (WIAS-ESH)
- Berliner Kolloquium Wahrscheinlichkeitstheorie
NN NN, NN:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
International Research Training Group 2544
- Wednesday, 28.01.2026, 17:15 (WIAS-ESH)
- Berliner Kolloquium Wahrscheinlichkeitstheorie
NN NN, NN:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
International Research Training Group 2544
- Thursday, 29.01.2026, 14:00 (WIAS-ESH)
- Seminar Numerische Mathematik
Dr. Jose Rodrigo Rojo Garcia, WIAS Berlin:
Inverse problems through the Bayesian paradigm
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
WIAS Berlin
- Thursday, 05.02.2026, 10:00 (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
more ... Location
Weierstraß-Institut, Hausvogteiplatz 11A, 10117 Berlin, 3. Etage, Raum: 3.04
Abstract
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.
Further Informations
Forschungsseminar Mathematische Modelle der Photonik
Host
WIAS Berlin
- Wednesday, 11.02.2026, 11:30 (WIAS-406)
- Seminar Interacting Random Systems
Elias Zimmermann, Universität Leipzig:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstract
tba
Further Informations
Seminar Interactin Random Systems
Host
WIAS Berlin
- Wednesday, 11.02.2026, 14:15 (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
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
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.
Further Informations
Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- February 12 – 13, 2026 (WIAS-ESH)
- Workshop/Konferenz: Widening the Scope of Rough and Stochastic Analysis -- Rough Women Reach Out!
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
Technische Universität Berlin
WIAS Berlin
- March 2 – 4, 2026 (IHP)
- Workshop/Konferenz: Leibniz MMS Days 2026
more ... Location
Leibniz Institute for High Performance Microelectronics Frankfurt/Oder
Host
Leibniz Institute for High Performance Microelectronics Frankfurt/Oder
WIAS Berlin
- June 1 – 5, 2026 (WIAS-ESH)
- Workshop/Konferenz: ESGI 194 - The Berlin Study Group with Industry
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
WIAS Berlin
- July 6 – 8, 2026 (WIAS-ESH)
- Workshop/Konferenz: Spreading Dynamics in Random Environment
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
WIAS Berlin