proposition: Lemma im_xcprodm : xcprodm @* C = fH @* H * fK @* K.
proof: Proof. by rewrite -im_cpair morphim_cprodm // !im_ifactm. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient action gproduct gfunctor) mathcomp(cyclic)