Wochenplan des Fachbereichs Mathematik und Informatik

The seminar will be held via zoom. If you are not a member of the topology group and wish to participate, write an e-mail to jens.reinhold@uni-muenster.de in order to receive the meeting ID.

Zoom-Meeting: https://wwu.zoom.us/j/97461739978 "The harmonic map equation is a second order semilinear elliptic PDE for maps between Riemannian manifolds for which many results on both existence and qualitative behaviour of its solutions have been obtained over the years. Recently, many researchers got attracted in higher order variants of harmonic maps. First, we will give an overview and present some recent results on biharmonic maps which constitute a fourth order generalization of harmonic maps. In the main part of the talk we will focus on a higher order generalization of harmonic maps initially proposed by Eells and Sampson in 1964 and present several recent results on the latter. This is joint work with Stefano Montaldo, Cezar Oniciuc and Andrea Ratto."

Categories of representations arising in Lie theory can often be modeled geometrically in terms of constructible sheaves on certain spaces, as for example on the flag variety, affine Grassmannian or the nilpotent cone. Recent developments in the theory of motives allow to consider so called "motivic sheaves", an algebro-geometric analogue of constructible sheaves. In this talk we will explain how one can practically work with motivic sheaves (using Grothendieck's six functor formalism) and apply them in representation theory. We will show how motivic sheaves can be used to model Category O associated to a reductive complex Lie algebra, modular Category O associated to a split reductive group over a finite field and categories of representations of convolution algebras, such as the graded affine Hecke algebra and KLR-algebras. We also will explain how more "exotic" versions of motivic sheaves provide exciting new opportunities in geometric representation theory.
https://wwu.zoom.us/j/98750589020

Further information

Because of the Corona crisis, the lectures will be given as online lectures via zoom (or other video conference software). Please contact us by sending a message to our secretary Elke Enning, if you are interested to participate, so that we can send you an invitation for the lectures.

Können Computer die Nullstellen eines Polynoms finden? Das klingt erst einmal wie eine relativ einfache Aufgabe. Aber kann man ein Programm schreiben, dass bei Eingabe eines Polynoms entscheidet, ob dieses Polynom Nullstellen in den natürlichen oder ganzen Zahlen hat? Und was hat diese Frage mit den berühmten Gödelschen Sätzen zu tun? Wir werden diese Fragen im Vortrag beantworten und die Zusammenhänge erklären. Dieser Vortrag kann hier abgerufen werden: https://www.youtube.com/watch?v=syuNJoNeCkk

I will present two results. A list of all one dimensional groups definable in the p-adic numbers up to a finite index subgroup and a quotient by a finite subgroup. And a list of all groups definable in Presburger arithmetic up to a finite index subgroup.