proposition: Lemma sub_cyclic_char G H : cyclic G -> (H \char G) = (H \subset G).
proof: Proof. case/cyclicP=> x ->; apply/idP/idP => [/andP[] //|]. exact: cycle_subgroup_char. 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)