proposition: Lemma fmodX n : {in A, {morph fmod : x / (x ^+ n)%g >-> x *+ n}}.
proof: Proof. exact: morphX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype bigop ssralg finset fingroup) mathcomp(morphism perm finalg action gproduct commutator) mathcomp(cyclic)