Oberseminar Geometrie, Topologie und Analysis

H. Geiges, A. Lytchak, G. Marinescu, S. Sabatini, G. Thorbergsson

Sommersemester 2016

Freitag, 10:30-11:30, Seminarraum 2 (Raum 204)

29.4.16 Anton Petrunin (Penn State, z.Zt. MPI Bonn)
Non-smooth saddle surfaces

Abstract: It is well known that smooth saddle surfaces in the Euclidean space have negative Gauss curvature. In this survey talk we will discuss couple of non-smooth generalizations of this statement.
6.5.16 Liviu Mare (Regina)
Assignments for topological group actions

3.6.16 Fernando Galaz-García
A look at isometric Lie group actions on Alexandrov spaces

Abstract: Alexandrov spaces (with curvature bounded below) are a natural synthetic generalization of Riemannian manifolds. In this talk I will discuss recent developments on the geometry and topology of Alexandrov spaces with isometric actions of compact Lie groups.
10.6.16 Chiara Esposito (Würzburg)
Rigidity and momentum map

17.6.16 Henrik Matthiesen (Bonn)
The analytic systole of Riemannian surfaces

Abstract: I will report on joint work in progress with W. Ballmann and S. Mondal. First, I will recall the most recent estimate on the number of small eigenvalues. Motivated by these I will then introduce the so-called analytic systole, explain its name and its relation to the bottom of the spectrum.
24.6.16 Joint Seminar on Complex Algebraic Geometry and Complex Analysis

1.7.16 Marco Radeschi (Münster)
Representation theory without groups

Abstract: We show that several results in classical representation theory hold for certain foliations, which mimic the decomposition into the orbits of an isometric action, but do not involve any (a priori) algebraic structure. This talk is based on joint works with Alexander Lytchak and Ricardo Mendes.

H. Geiges, 5.4.02