SIMPLE PERIODIC MODULES OF TWISTED CHEVALLEY-GROUPS

Consider a finite twisted Chevalley group constructed over a field of prime characteristic and its representations over an algebraically closed field of the same characteristic. In this paper we classify all those irreducible representations that are periodic, i.e., that have a periodic projective resolution. There is always the Steinberg module that is both simple and projective. We show that there are further periodic simple modules only for groups of types 2A2 and 2B2. © 1990 by Pacific Journal of Mathematics.