proposition: Lemma ler_pMn2l x : 0 < x -> {mono (@GRing.natmul R x) : m n / (m <= n)%N >-> m <= n}.
proof: Proof. move=> x_gt0 m n /=; case: leqP => hmn; first by rewrite ler_wpMn2l // ltW. by rewrite -(subnK (ltnW hmn)) mulrnDr gerDr lt_geF // mulrn_wgt0 // subn_gt0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)