IntegralCohomologyGenerators(R,n):: FreeResolution, Int --> List

Inputs at least n+1 terms of a free \mathbb ZG-resolution of \mathbb Z and the integer n \ge 1. It returns a minimal list of cohomology classes in H^n(G,\mathbb Z) which, together with all cup products of lower degree classes, generate the group H^n(G,\mathbb Z) .

(Let a_i be the i-th canonical generator of the d-generator abelian group H^n(G,Z). The cohomology class n_1a_1 + ... +n_da_d is represented by the integer vector u=(n_1, ..., n_d). )