Mara
GruĂź
Faster computations of Ehrhart, statistics of zonotopes in Sagemath
Search by speaker
Filter institution
Filter content
24. April
Today
Robert
Luce
Gurobi Optimization
Solving Nonlinear Problems to Global Optimality
Abstract.
In this talk, we provide an overview of Gurobi's algorithmic components for solving nonlinear optimization problems to global optimality. In essence, we extend our existing mixed-integer programming (MIP) framework to handle such problems. This includes our presolve algorithms, an extension of the branch-and-bound method utilizing spatial relaxations, and an interior point algorithm for nonlinear problems, which serves as a primal heuristic to find high-quality solutions. As a result, we can compute solutions to nonlinear optimization problems along with certificates for global optimality. Finally, we have extended gurobipy to facilitate the easy formulation of expression-based nonlinear optimization problems in Python. Gurobi's nonlinear solver applies to explicit expression-based constraints and does not require the supply of derivative data.
25. April
Tomorrow
Sven
Tornquist
FU Berlin
What is What is...the calculus of variations?
Abstract.
This talk offers a brief introduction to the calculus of variations, focusing on the core ideas behind variational problems and their role in describing systems governed by energy principles. We will explore how such methods arise in the modeling of grain boundaries in polycrystalline materials. The talk also includes a short overview of the concept of Γ-convergence, an important tool for studying the asymptotic behavior of variational problems.
Adriana
Garroni
Sapienza U Rome
Emergence of defects at grain boundaries: Variational analysis (Kovalevskaya Lecture)
29. April
Tue W17
Thomas
Creutzig
Erlangen Universität
Verlinde's formula in logarithmic conformal field theory
Abstract.
Verlinde's formula for rational two-dimensional conformal field theory says that the fusion rules can be computed from the modular transformations of characters. Thanks to Yi-Zhi Huang this is a theorem for rational vertex operator algebras. I will give a historical introduction to the subject and then introduce a setting in which this statement also holds for logarithmic conformal field theories.
Georgi
Mitzov
HU Berlin
30. April
Wed W17
Sebastian
Kassing
TU Berlin
Philipp
Bringmann
TU Wien
Anastasia
Giorgi
University of Calgary
Kevin
KĂĽhn
Goethe University Frankfurt
Holger
Stephan
WIAS
 Was sind Zahlen? Intuition oder Axiomatik in der Mathematik
Abstract.
 Obwohl die Zahlen seit Jahrtausenden nicht nur von Mathematikern richtig verwendet werden, wurden sie erst vor 150 Jahren axiomatisch begründet. Warum hat das so lange gedauert? Weil die Zahlen zwar intuitiv richtig verwendet werden, man aber nicht wusste (und eigentlich noch immer nicht weiß), warum. Warum ist es sinnvoll, die Summe 20 + 30 zu bilden, wenn diese Zahlen Anzahlen von Personen beschreiben, aber nicht, wenn es sich um Temperaturen handelt? Liegt die Anwendung der Zahlen (und überhaupt mathematischer Objekte) außerhalb der Mathematik? Will man Zahlen anwenden, muss man die bei der Axiomatisierung vorgenommene Identifizierung von Ordinal- und Kardinalzahlen rückgängig machen. Das teilt einige Objekte der angewandten Mathematik in zwei duale Welten. In der einen finden sich Ordinalzahlen, intensive physikalische Größen und stetige Funktionen wieder. In der anderen liegen Kardinalzahlen, extensive physikalische Größen und Radonmaße. Die Verwechslung dieser beiden Welten sollte vermieden werden, wenn man möchte, dass entwickelte mathematische Modelle die physische Realität möglichst gut widerspiegeln.
07. May
Wed W18
Robert
Auffarth
Universidad de Chile
Edriss
Titi
University of Cambridge, Texas A&M University and Weizmann Institute of Science
On a generalization of the Bardos-Tartar conjecture to nonlinear dissipative PDEs
Abstract
Rossella
Giorgio
TU Wien
Jonas
Sauer
FSU Jena
Michela
Ottobre
Heriot Watt University
12. May
Mon W19
Leonid
Chekhov
Michigan State University
Symplectic groupoid and cluster algebras
Abstract.
The symplectic groupoid is a set of pairs (B,A) with A unipotent upper-triangular matrices and B in GLn being such that the matrix A~ = BABT is itself unipotent upper triangular. It turned out recently that the problem of description of such pairs can be explicitly solved in terms of Fock--Goncharov--Shen cluster variables; moreover, for B satisfying the standard semiclassical Lie--Poisson algebra, the matrices B, A, and A~ satisfy the closed Poisson algebra relations expressible in the r-matrix form. Since works of J.Nelson, T.Regge and B.Dubrovin, it was known that entries of A can be identified with geodesic functions on Riemann surfaces with holes. In our approach, we are able to construct a complete set of geodesic functions for a closed Riemann surface. We have a complete description for genus two; I'm also about to discuss moduli spaces of higher genera. Based on my joint papers with MIsha Shapiro and our students.
13. May
Tue W19
Tim
Stiebert
HU Berlin
14. May
Wed W19
Vladimir
Spokoiny
WIAS/HU Berlin
Estimation and classification for DNN: Bless of dimension
Jenia
Tevelev
University of Massachusetts Amherst
Pierluigi
Colli
UniversitĂ Pavia, Italy
Solvability and optimal control in spatially structured epidemic models
Abstract
Andrea
Signori
Politecnico di Milano, Italy
Mathematical models of active phase separation and droplet dynamics
Abstract
15. May
Thu W19
Paul
Eisenberg
Wirtschaftsuniversität Wien
Thorsten
Schmidt
Universität Freiburg
16. May
Fri W19
Paolo
Rossi
Padova
Moduli spaces of curves and the classification of integrable systems
Abstract.
I will present several results and conjectures on the classification of different classes of integrable systems of evolutionary PDEs, up to the appropriate transformation groups. These include Hamiltonian systems, tau symmetric systems and systems of conservation laws. I will then explain in what sense we expect that integrable systems arising from intersection theory on the moduli space of stable curves are universal objects with respect to these classifications. In the rank one case I will present strong evidence in support of these claims. This is joint work with A. Buryak.
Danilo
Lewanski
Trieste
On the DR/DZ equivalence
Abstract.
There are two main recipes to associate to a Cohomological Field Theory (CohFT) an integrable hierarchy of hamiltonian PDEs: the first one was introduced by Dubrovin and Zhang (DZ, 2001), the second by Buryak (DR, 2015). It is interesting to notice that the latter relies on the geometric properties of the Double Ramification cycle — hence the name DR — to work. As soon as the second recipe was introduced, it was conjectured that the two had to be equivalent in some sense, and it was checked in a few examples. In the forthcoming years several papers by Buryak, Dubrovin, Guerè, Rossi and others followed, checking more examples of CohFTs, making the conjecture more precise, proving the conjecture in low genera, and eventually turning the statement of the conjecture in a purely intersection theoretic statement on the moduli spaces of stable curves. Lately, the conjecture was proved in its intersection theoretic form, employing virtual localisation techniques. (j.w.w. Blot, Rossi, Shadrin).
Reinier
Kramer
Milano Bicocca
Leaky Hurwitz numbers and topological recursion
Abstract.
Leaky Hurwitz numbers were introduced by Cavalieri-Markwig-Ranganathan by extending the branching morphism from the logarithmic double ramification cycle to its pluricanonical counterpart. These numbers also have a natural interpretation in terms of tropical geometry and yield (non-hypergeometric) KP tau functions. I will explain how to think about these numbers, and how we can extend the recent works of Alexandrov-Bychkov-Dunin-Barkowski-Kazarian-Shadrin to prove (at least blobbed) topological recursion. Along the way, I will interpret the cut-and-join operator as a hamiltonian whose flow generates the spectral curve. This is joint work in progress with M. A. Hahn.
21. May
Wed W20
Franziska
Eberle
MATH+ Junior Research Group Leader
Demand Strip Packing
Olaf
Klein
WIAS
Uncertainty quantification for a model for a magnetostrictive material involving a hysteresis operator
Adrian
Röllin
NU Singapore
Aleks
Mijatovic
U of Warwick
22. May
Thu W20
Johannes
Wiesel
Carnegie Mellon University
23. May
Fri W20
Artur
Avila
U ZĂĽrich
28. May
Wed W21
Moritz
Gau
WIAS
Sebastian
Boldt
TU Chemnitz
A lower bound on the normal radius of hypersurfaces with applications to bounded geometries with boundary
Abstract
04. June
Wed W22
Theresa
Simon
Universität Münster
05. June
Thu W22
Julian
Sester
National University Singapore
11. June
Wed W23
Martin
Brokate
WIAS and TU MĂĽnchen
Tobias
Boege
University of Tromsø
Entropy profiles and algebraic matroids
Abstract.
Consider the uniform probability distribution on the solution set of a polynomial system with coefficients in a finite field k. When K ranges over the finite extensions of k, this defines a sequence of distributions and we are interested in their Shannon entropy profiles. Using results from the model theory of finite fields, we identify all convergent subsequences and compute their limits. The computability part relies on a difficult symbolic algorithm known as Galois stratification. In the special case that the polynomials define a k-irreducible algebraic variety, one of these limits turns out to be its algebraic matroid, which recovers a result previously obtained by F. Matúš.
18. June
Wed W24
Christophe
Roux
ZIB
Bounding geometric penalties in Riemannian optimization
Abstract.
Riemannian optimization refers to the optimization of functions defined over Riemannian manifolds. Such problems arise when the constraints of Euclidean optimization problems can be viewed as Riemannian manifolds, such as the symmetric positive-definite cone, the sphere, or the set of orthogonal linear layers for a neural network. This Riemannian formulation enables us to leverage the geometric structure of such problems by viewing them as unconstrained problems on a manifold. The convergence rates of Riemannian optimization algorithms often rely on geometric quantities depending on the sectional curvature and the distance between iterates and an optimizer. Numerous previous works bound the latter only by assumption, resulting in incomplete analysis and unquantified rates. In this talk, I will discuss how to remove this limitation for multiple algorithms and as a result quantify their rates of convergence.
Jonas
Tölle
Alto University
Chencheng
Ling
U of Augsburg
19. June
Thu W24
Rowan
Turner
University of Edinburgh
25. June
Wed W25
Shigeru
Mukai
Kyoto
Tomáš
RoubĂÄŤek
Charles University Prague and Inst. of Thermomechanics, Czech Acad. Sci.
27. June
Fri W25
Mukai
Shigeru
Kyoto U
02. July
Wed W26
Benjamin
Gess
TU Berlin and MPI Leipzig
Fabio
Toninelli
TU Vienna
Mathieu
Laurière
NYU Shanghai
03. July
Thu W26
Oliver
Sander
Technische Universität Dresden
Mathieu
Lauriere
NYU Shanghai
Sören
Christensen
Christian-Albrechts-Universität zu Kiel
04. July
Fri W26
Silvia
De Toffoli
IUSS Pavia
Kovalevskaya Lecture
06. July
Sun W26
09. July
Wed W27
16. July
Wed W28
Alice
Marveggio
Hausdorff Center for Mathematics Universität Bonn