Mathematisches Kolloquium

Das allgemeine Kolloquium des mathematischen Instituts findet während der Vorlesungszeit donnerstags um 17:15 Uhr im Raum 05-426 (hybrid) statt. Ab 16:45 Uhr gibt es im Hilbertraum (05-432) oder Kaffee und Kuchen.

(Teilnahme auch online möglich, Zugangsdaten über den Koll.beauftragten.)


Programm Wintersemester 2022/23

03.11. Prof. Dr. Wadim Zudilin (Radboud University Nijmegen)
Irrationality by experiment

Abstract: The majority of real numbers are irrational, however establishing this for very concrete numbers (like the values of Riemann's zeta function and general L-functions at positive integers) remains a difficult task. In my talk I will (try to) give some insights into how Experimental Mathematics assists us in constructing good rational approximations to the quantities represented by period integrals.

10.11. Prof. Dr. Eduard Feireisl (Academy of Sciences, Prague)
The Euler system in fluid mechanics: Good and bad news

Abstract: We discuss some recent results concerning well/ill posedness of the Euler system describing the dynamics of a compressible viscous fluid. In particular, we address the following topics:
1. Density of the "wild'' data.
2. Euler system as an inviscid limit.
3. Measurable semigroup solution.

24.11. Dr. Emre Sertöz (Univ. Hannover)
Separating period integrals of quartic surfaces

Abstract: Periods form a natural number system that extends the algebraic numbers by adding values of integrals coming from geometry and physics. Because there are countably many periods, one would expect it to be possible to compute effectively in this number system. This would require an effective height function and the ability to separate periods of bounded height, neither of which are even remotely possible in general. I will, however, introduce a separation constant to numerically verify identities coming from integrals related to quartic surfaces in 3-space, i.e., related to K3 surfaces. This is joint work with Pierre Lairez.

1.12. Prof. Dr. Hartmut Monien (Univ. Bonn)
Dessins d'enfants and modular curves associated to the sporadic groups Co3 and Janko2 or how to solve a set of 276 polynomial equations of degree 276 in 276 variables explicitly

Abstract: Dessins d'enfants and their realization as Belyi maps of compact Riemann surfaces were originally discovered by Felix Klein. Their importance and relevance was finally understood by Alexander Grothendieck who rediscovered and named them in his "Esquisse d'un programme" in 1984. The most important aspect of dessins is the operation of the absolute Galois group on them. Accordingly, dessins d'enfants provide fascinating insights and fundamental links between different fields of mathematics like inverse Galois theory, Teichmüller spaces, hypermaps, algebraic number theory and mathematical physics. The sporadic groups Janko 2 and Conway 3 are stabilizers of pair of lines in the 24-dimensional Leech lattice. In my talk I will show how to explicitly construct modular curves with automorphism groups J2 and Co3 using methods from applied mathematics.

08.12. Prof. Dr. Thomas Nikolaus (Univ. Münster)
Title tba

15.12. Brittany Shields, PhD (Univ. of Pennsylvania)
Scientific Diplomacy: Cold War Mathematicians and International Relations



19.01. Dr. Hans Fischer (Kath. Univ. Eichstädt)
Real Analysis Around 1830/40: Propagation and Further Development of Cauchy's Basic Concepts by Peter Gustav Lejeune Dirichlet

26.01. Prof. Dr. Catharina Stroppel (Univ. Bonn)
Titel tba

02.02. Prof. Dr. Lutz Weis (Karlsruher Institut für Technologie)
Title tba



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