proposition: Lemma injm_center G : G \subset D -> f @* 'Z(G) = 'Z(f @* G).
proof: Proof. exact: injm_subcent. 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)