Bounded complexes of permutation modules

Abstract

Let k k be a field of characteristic p > 0 p > 0 . For G G an elementary abelian p p -group, there exist collections of permutation modules such that if C ∗ C^* is any exact bounded complex whose terms are sums of copies of modules from the collection, then C ∗ C^* is contractible. A consequence is that if G G is any finite group whose Sylow p p -subgroups are not cyclic or quaternion, and if C ∗ C^* is a bounded exact complex such that each C i C^i is a direct sum of one dimensional modules and projective modules, then C ∗ C^* is contractible.