Department of Mathematics, University of Wisconsin, Madison, Wisconsin 53706 ; Department of Mathematics, Limburgs Universitair Centrum, B-3590 Diepenbeek, Belgium
Abstract:
We study the semi-invariants and weights of a group algebra over a field of characteristic zero. Specifically, we show that certain basic results which hold when is a polycyclic-by-finite group with need not hold in the case of group algebras of finite groups. This turns out to be a purely group theoretic question about the existence of class preserving automorphisms.