proposition: Lemma quotient_odd : odd #|K| -> odd #|K / H|.
proof: Proof. exact: morphim_odd. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset prime fingroup morphism) mathcomp(gfunctor automorphism quotient action gproduct) mathcomp(cyclic)