HomToIntegers(C):: ChainComplex --> CochainComplex
HomToIntegers(R):: FreeResolution --> CochainComplex
HomToIntegers(F):: EquiChainMap --> CochainMap

Inputs a chain complex C of free abelian groups and returns the cochain complex Hom_{\mathbb Z}(C,\mathbb Z).

Inputs a free \mathbb ZG-resolution R in characteristic 0 and returns the cochain complex Hom_{\mathbb ZG}(R,\mathbb Z).

Inputs an equivariant chain map F\colon R\rightarrow S of resolutions and returns the induced cochain map Hom_{\mathbb ZG}(S,\mathbb Z) \longrightarrow Hom_{\mathbb ZG}(R,\mathbb Z).