proposition: Lemma quotient_cycle x H : x \in 'N(H) -> <[x]> / H = <[coset H x]>.
proof: Proof. exact: morphim_cycle. 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)