proposition: Lemma morph_order : #[f x] %| #[x].
proof: Proof. by rewrite order_dvdn -morphX // expg_order morph1. 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)