proposition: Lemma coprime_morphr G p : coprime p #|G| -> coprime p #|f @* G|.
proof: Proof. exact: coprime_dvdr (dvdn_morphim G). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div) mathcomp(choice fintype prime finset fingroup morphism) mathcomp(automorphism)