Veranstaltungen
- Dienstag, 02.12.2025, 10:00 Uhr (Online Event)
- Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations / Mathematical Optimization
Shida Wang, Universität des Saarlandes:
Convergence rates of regularized quasi-Newton methods without strong convexity (online talk)
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Online Event
Abstrakt
In this talk, we discuss the convergence rates of the cubic regularized proximal quasi-Newton method for solving non-smooth additive composite problems that satisfy the Kurdyka-Łojasiewicz (KL) property with respect to some desingularizing function, instead of relying on strong convexity. In particular, when the objective function is smooth and satisfies the Polyak-Łojasiewicz (PL) inequality, the algorithm attains a global superlinear convergence. Additionally, we introduce two practical and computationally efficient variants based on limited-memory quasi-Newton techniques.
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Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations
Veranstalter
WIAS Berlin
- Dienstag, 02.12.2025, 15:00 Uhr (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. Davit Gogolashvili, WIAS Berlin:
Local regression on path spaces with signature metrics
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstrakt
We study nonparametric regression and classification for path-valued data. We introduce a functional Nadaraya-Watson estimator that combines the signature transform from rough path theory with local kernel regression. The signature transform provides a principled way to encode sequential data through iterated integrals, enabling direct comparison of paths in a natural metric space. Our approach leverages signature-induced distances within the classical kernel regression framework, achieving computational efficiency while avoiding the scalability bottlenecks of large-scale kernel matrix operations. We establish finite-sample convergence bounds demonstrating favorable statistical properties of signature-based distances compared to traditional metrics in infinite-dimensional settings. We propose robust signature variants that provide stability against outliers, enhancing practical performance. Applications to both synthetic and real-world data-including stochastic differential equation learning and time series classification-demonstrate competitive accuracy while offering significant computational advantages over existing methods.
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Dieser Vortrag findet auch via Zoom statt: https://wias-berlin-de.zoom-x.de/j/69982487566
Veranstalter
WIAS Berlin
- Mittwoch, 03.12.2025, 10:00 Uhr (WIAS-ESH)
- Forschungsseminar Mathematische Statistik
Fanny Seyzilles, University of Cambridge, GB:
Inferring diffusivity from killed diffusion
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
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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, 03.12.2025, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Alexander Mielke, WIAS Berlin:
A simple approach to the chain rule for gradient systems
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
For constructing solutions for gradient systems, one usually approximates the problem, e.g. via the minimizing movement scheme, and then passes to the limit. By this way one obtains an energy-dissipation inequality and has to prove that this inequality is indeed an equality. For this one has to establish a chain rule for the energy functional within the class of curves satisfying only the natural dissipation and slope bounds. We present a simple approach that is based on the classical duality pairing in Lp spaces instead of the often used metric approach in measure spaces. We show that this approach allows the treatment of a reasonably large class of nonlinear diffusion equations. Moreover, it is flexible enough to be generalized to systems of diffusion equations.
Veranstalter
Humboldt-Universität zu Berlin
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
- 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
Weitere Informationen
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
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Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Veranstalter
WIAS Berlin