proposition: Lemma actAr x : {morph actr^~ x : u v / u + v}.
proof: Proof. by move=> u v; apply: val_inj; rewrite !(fmvalA, fmvalJcond) conjMg; case: ifP. 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)