proposition: Lemma morphim_center : GFunctor.pcontinuous (@center).
proof: Proof. by move=> gT rT G D f; apply: morphim_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)