Upcoming talks:
7 X  Artem Dudko (IM PAN) From invariant ergodic measures to indecomposable characters on full groups. Show abstract
Given a measurepreserving group action $(\mu, X, G)$ one can associate to it a character (positivedefinite conjugacy invariant function) on $G$ by
\begin{align*}
\chi(g)=\mu(\{x \in X: g x=x\}), g \in G .
\end{align*}
Anatoly Vershik suggested that for a "sufficiently rich" simple group $G$ every indecomposable character (extreme point in the space of characters) on $G$ can be obtained by formula (1)
from some ergodic measurepreserving action of $G$.
Given a Cantor minimal system one can associate to it two important groups of actions: the topological full group of the system and the approximately finite group of the related Bratteli diagram.
In my talk I will explain the correspondence (1) for these groups and outline the proof of a generalization of Vershik's conjecture for them. The talk is based on an ongoing joint work with Konstantin Medynets.

Show rest
13 V  Davide Ravotti (University of Vienna) Large hyperbolic circles Show abstract The projections of large circles in R^2 onto the standard torus T^2 become equidistributed as the radius of the circles goes to infinity. In this talk, we consider the analogous problem in the hyperbolic setting; more precisely, for any compact hyperbolic surface, we provide a precise asymptotic expansion of the equidistribution rate of arbitrary circle arcs of large radius. The method we use is inspired by the works of Ratner on quantitative mixing properties of the geodesic flow and of Burger.
Furthermore, we discuss related distributional limit theorems and we give an explicit bound on the error term in the corresponding hyperbolic lattice counting problem (albeit weaker than the known estimates, which have been proved by Selberg and others using number theoretical methods).
This is a joint work with E. Corso. 
The seminar takes place on Fridays
at 10.1511.45 AM (Kraków time)  currently CEST (UTC+2) in the room 1016
of the Jagiellonian University
Department of Mathematics
and Computer Science
(ul. Łojasiewicza 6, Cracow).