COKERNELS OF HOMOMORPHISMS FROM BURNSIDE RINGS TO INVERSE LIMITS II: G = Cpm × Cpn

Abstract

Let G be a finite group and A(G) the Burnside ring of G. The family of rings A(H), where H ranges over the set of all proper subgroups of G, yields the inverse limit L(G) and a canonical homomorphism from A(G) to L(G) which is called the restriction map. Let Q(G) be the cokernel of this homomorphism. It is known that Q(G) is a finite abelian group and is isomorphic to the cartesian product of Q(G/N (p)), where p runs over the set of primes dividing the order of G and N (p) stands for the smallest normal subgroup of G such that the order of G/N (p) is a power of p. Therefore, it is important to investigate Q(G) for G of prime power order. In this paper we develop a way to compute Q(G) for cartesian products G of two cyclic p-groups.