proposition: Fact transfer_morph_subproof : H \subset alpha @*^-1 (alpha @* H).
proof: Proof. by rewrite -sub_morphim_pre. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype bigop ssralg finset fingroup) mathcomp(morphism perm finalg action gproduct commutator) mathcomp(cyclic)