Orateur(s)  Vadim Kaimanovich  University of Ottawa,

Titre  Amenability, approximate invariance and the Liouville property 
Date  05/04/2018 
Horaire  10:30 à 14:16 

Diffusion  
Résume  The class of amenable groups was introduced by von Neumann in 1929 to explain the HausdorffBanachTarski paradox. This original definition was given in highly nonconstructive terms of invariant means. A much more constructive characterization of amenability in terms of approximately invariant measures was only given in the 1950s by Day (although the phenomenon was definitely known much earlier). Both of them are also closely related to the Liouville property, i.e., to the absence of nonconstant bounded harmonic functions.
I will overview the historical background and outline a number of new results on the amenability beyond the group setting. 
Salle  salle 13  couloir 1516  4ème étage 
Adresse  Campus Pierre et Marie Curie 