Veranstaltungen
- Dienstag, 09.12.2025, 15:00 Uhr (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Jakob Kellermann, WIAS Berlin:
Stochastic localization based sampling
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstrakt
We study theoretically a Stochastic Localization based algorithm introduced by Grenioux et al. (https://proceedings.mlr.press/v235/grenioux24a.html) that aims at sampling highly multi-modal probability measures.
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Dieser Vortrag findet auch via Zoom statt: https://wias-berlin-de.zoom-x.de/j/69982487566
Veranstalter
WIAS Berlin
- Mittwoch, 10.12.2025, 10:00 Uhr (WIAS-ESH)
- Forschungsseminar Mathematische Statistik
Vladimir Spokoiny, WIAS Berlin:
Penalized MLE in high-dimensional logistic regression
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
This talk focuses on a popular logistic regression model in the case of a large or even infinite parameter dimension, limited sample size, and possible model misspecification. Recent studies highlighted new effects and phenomena appearing in highly or overparametrized regimes; see e.g. Bartlett et al. (2020), Sur and Candès (2019); Candès and Sur (2020), Bach (2024), Montanari et al. (2025), among others. The properties of the random design in high-dimensional regimes give rise to significant challenges for statistical analysis and inference. Existing strategies to mitigate these issues include tailored gradient-based methods with appropriate step-size choices and stopping criteria, as well as alternative regularization techniques for the logistic loss. In line with Cheng and Montanari (2022), this work examines a simple ridge-penalized formulation in possibly infinite-dimensional settings. The central question addressed is how to select the ridge tuning parameter while preserving standard accuracy guarantees and enabling valid inference.
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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
Veranstalter
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
- Mittwoch, 10.12.2025, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Peter Bella, Technische Universität Dortmund:
From regularity theory for elliptic equations to invariance principle for random walks
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
This talk addresses regularity for elliptic equations under merely averaged ellipticity conditions and establishes sharp criteria ensuring local boundedness and Harnack inequalities. These results extend the classical De Giorgi--Nash--Moser theory and yield new applications to variational integrals with (p, q)-growth. In the second part, the same regularity ideas are applied to the random conductance model, leading--under optimal moment assumptions--to a quenched invariance principle and a local limit theorem. The results highlight a close connection between regularity theory and stochastic homogenization.
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Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- Mittwoch, 17.12.2025, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Sebastian Hensel, Universität Leipzig:
A weak-strong uniqueness principle for the Mullins--Sekerka equation
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
We establish a weak-strong uniqueness principle for the two-phase Mullins--Sekerka equation in ambient dimension d = 2 and 3: As long as a classical solution to the evolution problem exists, any weak De Giorgi type varifold solution (see for this notion the recent work with Stinson, Arch. Ration. Mech. Anal. 248, 8, 2024) must coincide with it. In particular, in the absence of topology changes such weak solutions do not introduce a mechanism for (unphysical) non-uniqueness. We also derive a stability estimate with respect to changes in the data. I will explain our method which is based on the notion of relative entropies for interface evolution problems, a reduction argument to a perturbative setting, and a stability analysis in this perturbative regime relying crucially on the gradient flow structure of the Mullins--Sekerka equation. This is joint work with Julian Fischer, Tim Laux and Theresa M. Simon.
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Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- 12. – 13. Januar 2026 (WIAS-ESH)
- Workshop/Konferenz: Recent Trends in Coupled Network Systems
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Veranstalter
WIAS Berlin
- Mittwoch, 14.01.2026, 11:30 Uhr (WIAS-406)
- Seminar Interacting Random Systems
Marcel Ortgiese, University of Bath:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstrakt
tba
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Seminar Interactin Random Systems
Veranstalter
WIAS Berlin
- Donnerstag, 15.01.2026, 14:00 Uhr (WIAS-405-406)
- Seminar Numerische Mathematik
Prof. Petr Knobloch, Charles University, Tschechische Republik:
Computation of stabilization parameters using machine learning
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstrakt
For various types of partial differential equations, standard finite element discretizations are often unstable, which can be cured by adding suitable stabilization terms. Typically, these terms contain user-chosen parameters whose optimal choice is usually not known but which considerably influence the quality of the approximate solution. In this talk, we will consider stabilized methods for steady convection-diffusion equations. A typical example is the streamline upwind Petrov-Galerkin (SUPG) method. It is possible to compute the stabilization parameters a posteriori in an adaptive way by minimizing a target functional characterizing the quality of the approximate solution, however, this functional is often difficult to design. Moreover, the solution of this high-dimensional constrained nonlinear optimization problem is usually very time-consuming. Therefore, we proposed a method based on techniques from machine learning in order to select (nearly) optimal stabilization parameters in a cheap way. The idea is to compute these parameters locally based on properties of the SUPG solution obtained with standard (nonoptimal) parameters. The training phase will use parameters computed by the mentioned minimization approach employing accurate approximate solutions which can be obtained using nonlinear (and hence again costly) approaches. We will report our first experiences with this strategy. This is the joint work with Manoj Prakash (Charles University, Prague).
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Seminar Numerical Mathematics
Veranstalter
WIAS Berlin
- Mittwoch, 21.01.2026, 11:30 Uhr (WIAS-406)
- Seminar Interacting Random Systems
Yannic Steenbeck, TU Braunschweig:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstrakt
tba
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Seminar Interactin Random Systems
Veranstalter
WIAS Berlin
- Mittwoch, 21.01.2026, 14:15 Uhr (WIAS-ESH)
- 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
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- Mittwoch, 28.01.2026, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Anastasija Pešić, WIAS Berlin:
Curvature-driven pattern formation in biomembranes: A gradient flow approach
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- Mittwoch, 11.02.2026, 11:30 Uhr (WIAS-406)
- Seminar Interacting Random Systems
Elias Zimmermann, Universität Leipzig:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstrakt
tba
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Seminar Interactin Random Systems
Veranstalter
WIAS Berlin
- 2. – 4. März 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
- 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
