Le jeudi 15 décembre 2016 à 17h00 - Salle 430Alexandre Bellis
In this talk, we are going to start from a problem in ?² : we take the vector of coordinates (1, 0) in ?² and try to understand what its orbit may be under some subgroup of SL(2, ?). Is it a discrete orbit ? Are there some accumulations points ? etc. To answer these questions, we will introduce hyperbolic geometry and explain how to use it.