proposition: Lemma amulr_is_multiplicative : multiplicative amulr.
proof: Proof. split=> [x y|]; last by apply/lfunP => w; rewrite id_lfunE !lfunE /= mulr1. by apply/lfunP=> w; rewrite comp_lfunE !lfunE /= mulrA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype div tuple finfun bigop ssralg) mathcomp(finalg zmodp matrix vector poly)