proposition: Lemma exprzMl x y n (ux : x \is a GRing.unit) (uy : y \is a GRing.unit) : (x * y) ^ n = x ^ n * y ^ n.
proof: Proof. by rewrite exprMz_comm //; apply: mulrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)