Orateur
Luca Froger
Description
Amenable groups have historically been introduced as a response to the Banach-Tarski paradox, which states that one can separate a ball in a disjoint union of subsets, rotate said subsets around and obtain two copies of the original ball. I will present this notion in this classical framework, and more precisely a common strategy to prove amenability: finding Følner sequences. This will lead us to a result of Alex Eskin, David Fisher and Kevin Whyte using Følner sequences in a slightly different context. This result is a good example on how to use Følner sequences without information on any group in order to study behaviors of areas and volumes.
