Reduction of cuspidal characters of finite reductive groups
For representations of finite groups, there is a decomposition map that produces modular representations (over a field of positive characteristic) from ordinary representations (over a field of characteristic zero). The image of an irreducible ordinary representation is no longer irreducible in general. The purpose of this talk is to explain that it is nevertheless the case for a special class of representations of finite reductive groups, no matter what the characteristic is. This is a joint work with G. Malle.