proposition: Lemma quotient_generator x G H : x \in 'N(H) -> generator G x -> generator (G / H) (coset H x).
proof: Proof. by move=> Nx; apply: morph_generator. 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)