Berlin Math Seminars

Tue, 06. Jan at 11:15

1.023 (BMS Room, ...

Gaëtan Borot HU Berlin

Panorama of matrix models and topological recursion III

Abstract.

This is crash course which aims at explaning various aspects of: random matrix ensembles and Coulomb gases, loop equations, spectral curves, topological recursion, maps, free probability, how they fit together and pose some open problems.

Math. Statistics

Wed, 07. Jan at 10:00

Weierstrass-Insti...

Frank Konietschke Charité

Algebraic Geometry

Wed, 07. Jan at 13:15

Room: 3.007 John ...

George Hitching OSLOMET

Secant loci of scrolls over curves

Abstract.

The secant loci associated to a linear system \(l\) over a curve C parametrise effective divisors which impose fewer conditions than expected on \(l\). For a rank \(r\) bundle \(E\) and a space of global sections of \(E\), we define and investigate generalised secant loci, which are determinantal loci on Quot schemes of torsion quotients of \(E\). We extend the Abel-Jacobi map to the context of Quot schemes, and examine the relation between smoothness of generalised secant loci and their associated Brill-Noether loci. In one case, we indicate how formulas of Oprea-Pandharipande and Stark can be used to enumerate the generalised secant locus when it has and attains expected dimension zero.

Langenbach

Wed, 07. Jan at 14:15

WIAS, Erhard-Schm...

André Erhardt WIAS

Nonlinear dynamics of complex biophysical processes

Abstract

Math. Physics

Tue, 13. Jan at 11:15

1.023 (BMS Room, ...

Piotr Sulkowski University of Warsaw

Numerical Analysis

Tue, 13. Jan at 13:15

Humboldt-Universi...

Konstantin Viol HU Berlin

Math. Statistics

Wed, 14. Jan at 10:00

Weierstrass-Insti...

Ulrike Schneider Universität Wien

Math. Statistics

Wed, 14. Jan at 10:00

Weierstrass-Insti...

Frank Konietschke Charité

Random Systems

Wed, 14. Jan at 11:30

Weierstrass Lectu...

Marcel Ortgiese University of Bath

Dynamic accessibility percolation

Abstract.

Accessibility percolation is a simple model in evolutionary biology describing how a population driven by the evolutionary forces of selection and mutation explores a fitness landscape. Mathematically, the fitness landscape is modeled by attaching random weights to the vertices of a graph. Then, accessible percolation asks whether there are paths of increasing fitness of a certain length. I will review some of the progress in this area and then consider the question what happens if the fitness landscape changes over time. In particular, I will focus on the case when the underlying graph is a regular tree. Depending on the ratio of depth to width of the tree, we will see different scaling regimes for the time it takes to see an increasing path. Some of the proofs rely on adapting techniques from the area of noise sensitivity for Boolean functions.

Langenbach

Wed, 14. Jan at 14:15

WIAS, Erhard-Schm...

André Erhardt WIAS

Group Theory

Wed, 14. Jan at 14:30

TU Berlin, MA Bui...

Matthew Konefal Loughborough, UK

Probability

Wed, 14. Jan at 16:00

Marcel Ortgiese U Bath

Discrete Math

Wed, 14. Jan at 16:30

EN 058

Mikhail Gorsky Jean Monnet University

Stochastic Analysis

Thu, 15. Jan at 17:15

HU Berlin, Instit...

Francesca Primavera University of California

Analysis

Fri, 16. Jan

Daan Janssen University of York

Math. Physics

Tue, 20. Jan at 11:15

1.023 (BMS Room, ...

Burkhard Eden HU Berlin

The off-shell one and two-loop box recovered from intersection theory

Abstract.

We advertise intersection theory for generalised hypergeometric functions as a means of evaluating Mellin-Barnes representations. As an example, we study two-parameter representations of the off-shell one- and two-loop box graphs in exactly four-dimensional configuration space. Closing the integration contours for the MB parameters we transform these into double sums. Polygamma functions in the MB representation of the double box and the occurrence of higher poles are taken into account by parametric differentiation. Summing over any one of the counters results into a p+1F p that we replace by its Euler integral representation. The process can be repeated a second time and results in a two- or four-parameter Euler integral, respectively. We use intersection theory to derive Pfaffian systems of equations on related sets of master integrals and solve for the box and double box integrals reproducing the known expressions. Finally, we use a trick to re-derive the double box from a two-parameter Euler integral. This second computation requires only very little computing resources.

Numerical Analysis

Tue, 20. Jan at 13:15

Humboldt-Universi...

Falk Hante HU Berlin

Stabilizing PDE Control: Optimization and Feedback in Moving Horizons

Math. Statistics

Wed, 21. Jan at 10:00

Weierstrass-Insti...

Ulrike Schneider Universität Wien

Random Systems

Wed, 21. Jan at 11:30

Weierstrass Lectu...

Yannic Steenbeck TU Braunschweig

Langenbach

Wed, 21. Jan at 14:15

WIAS, Erhard-Schm...

Olaf Klein WIAS

Uncertainty quantification for a model for a magnetostrictive material involving a hysteresis operator

Group Theory

Wed, 21. Jan at 14:30

TU Berlin, MA Bui...

Jan Moritz Petschick Uni Bielefeld

Optimization

Thu, 22. Jan at 15:15

Rudower Chaussee ...

Raphael Kuess HU Berlin

Analysis

Fri, 23. Jan

Malte Leimbach MPI Bonn

Analysis

Fri, 23. Jan

Janina Bernardy MPI Bonn

Math. Physics

Tue, 27. Jan at 11:15

1.023 (BMS Room, ...

Maciej Dolega Institute of Mathematics, Polish Academy of Sciences

Math. Statistics

Wed, 28. Jan at 10:00

Weierstrass-Insti...

Jakob Runge Universität Potsdam

Langenbach

Wed, 28. Jan at 14:15

WIAS, Erhard-Schm...

Anastasija Pešić WIAS

Curvature-driven pattern formation in biomembranes: A gradient flow approach

Probability

Wed, 28. Jan at 16:00

Rüdiger Frey WU Vienna

Probability

Wed, 28. Jan at 16:00

Andrew Allen U Durham

Stochastic Analysis

Thu, 29. Jan at 16:15

HU Berlin, Instit...

Xiaofei Sei University of Toronto

Analysis

Thu, 29. Jan at 16:15

Claudio Dappiaggi University of Pavia

Equivalence between local and global Hadamard States with Robin boundary conditions on half-Minkowski spacetime

Abstract.

We construct the fundamental solutions and Hadamard states for a Klein-Gordon field in half-Minkowski spacetime with Robin boundary conditions in arbitrary dimensions using a generalisation of the Robin-to-Dirichlet map. On the one hand this allows us to prove the uniqueness and support properties of the Green operators. On the other hand, we obtain a local representation for the Hadamard parametrix that provides the correct local definition of Hadamard states, capturing `reflected' singularities from the spacetime timelike boundary. This allows us to prove the equivalence of our local Hadamard condition and the global Hadamard condition with a wave-front set described in terms of generalized broken bicharacteristics, obtaining a Radzikowski-like theorem in half-Minkowski spacetime. Joint work with B. Costeri, R. D. Singh and B. Juárez-Aubry -- ArXiv: 2509.26035 [math-ph].

Stochastic Analysis

Thu, 29. Jan at 17:15

HU Berlin, Instit...

Alessandro Bondi École Polytechnique Paris

Analysis

Fri, 30. Jan

Beatrice Costeri University of Pavia

MATH+ Friday

Fri, 30. Jan at 14:15

HU

Alexei Skorobogatov Imperial College London

Math. Physics

Tue, 10. Feb at 11:15

1.023 (BMS Room, ...

Andrea Brini Sheffield University

On the conifold gap for the local projective plane

Abstract.

The conifold gap conjecture asserts that the polar part of the Gromov-Witten potential of a Calabi-Yau threefold near its conifold locus has a universal expression described by the logarithm of the Barnes G-function. In this talk I will describe a proof of the conifold gap conjecture for the local projective plane, whereby the higher genus conifold Gromov-Witten generating series of local P^2 are related to the thermodynamics of a certain statistical mechanical ensemble of repulsive particles on the positive half-line. As a corollary, this establishes the all-genus mirror principle for local P^2 through the direct integration of the BCOV holomorphic anomaly equations.

Math. Statistics

Wed, 11. Feb at 10:00

Weierstrass-Insti...

Ho Yun EPFL

Linear Monge is All You Need

Abstract.

In this talk, we explore the geometry of the Bures-Wasserstein space for potentially degenerate Gaussian measures on a separable Hilbert space, based on our recent work with Yoav Zemel. A key feature of our approach is its simplicity: relying only on elementary arguments from linear operator theory, we are able to derive explicit results without resorting to Kantorovich duality or Otto's Calculus. We provide a complete characterisation of both the Monge and Kantorovich problems in this context, regardless of the degeneracy of their measures. Furthermore, we show a simple way to construct all possible Wasserstein geodesics connecting two Gaussian measures. Finally, we generalise our results to characterise Wasserstein barycenters of Gaussian measures, borrowing the idea of Procrustes distance from statistical shape analysis.

Math. Statistics

Wed, 11. Feb at 10:00

Weierstrass-Insti...

Béatrice Matteo University of Geneva

Kernel ridge regression for spherical responses

Abstract.

The aim is to propose a novel nonlinear regression framework for responses taking values on a hypersphere. Rather than performing tangent space regression, where all the sphere responses are lifted to a single tangent space on which the regression is performed, we estimate conditional Fréchet means by minimizing squared distances on the nonlinear manifold. Yet, the tangent space serves as a linear predictor space where the regression function takes values. The framework integrates Riemannian geometry techniques with functional data analysis by modelling the regression function using methods from vector-valued reproducing kernel Hilbert space theory. This formulation enables the reduction of the infinite-dimensional estimation problem to a finite-dimensional one via a representer theorem and leads to an estimation algorithm by means of Riemannian gradient descent. Explicit checkable conditions on the data that ensure the existence and uniqueness of the minimizing estimator are given.

Random Systems

Wed, 11. Feb at 11:30

Weierstrass Lectu...

Elias Zimmermann Universität Leipzig

Langenbach

Wed, 11. Feb at 14:15

WIAS, Erhard-Schm...

Andrea Poiatti Universität Wien

Probability

Wed, 11. Feb at 16:00

Tony Lelievre CERMICS

Probability

Wed, 11. Feb at 16:00

Vitalii Konarovskyi U Hamburg

Stochastic Analysis

Thu, 12. Feb at 16:15

HU Berlin, Instit...

Guido Gazzani University of Verona

Stochastic Analysis

Thu, 12. Feb at 17:15

HU Berlin, Instit...

Beatrice Ongarato Technische Universität Dresden

Discrete Math

Sat, 14. Feb at 16:30

EN 058

Mikhail Gorsky Jean Monnet University

Langenbach

Wed, 15. Apr at 14:15

WIAS, Erhard-Schm...

Pierluigi Colli Università Pavia, Italy

Langenbach

Thu, 16. Apr at 14:15

WIAS, Erhard-Schm...

José Antonio Carrillo University of Oxford, United Kingdom

Math. Physics

Tue, 21. Apr at 11:15

1.023 (BMS Room, ...

Pierrick Bousseau Oxford University

Math. Physics

Tue, 05. May at 11:15

1.023 (BMS Room, ...

Damien Simon Sorbonne Universite

Math. Physics

Tue, 14. Jul at 11:15

1.023 (BMS Room, ...

Alexander Alexandrov IBS Pohang

Discrete Math

Thu, 17. Dec at 16:30

EN 058

Lars Kastner TU Berlin

Drawing algebraic curves in OSCAR

Abstract.

I will talk about how to visualize real plane algebraic curves given as the zero set of a polynomial in two variables using Oscar.jl. I will highlight performance and exactness issues using real world examples.