proposition: Lemma isog_cyclic G M : G \isog M -> cyclic G = cyclic M.
proof: Proof. by case/isogP=> f injf <-; rewrite injm_cyclic. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice div) mathcomp(fintype bigop prime finset fingroup morphism) mathcomp(perm automorphism quotient gproduct ssralg) mathcomp(finalg zmodp poly)