proposition: Lemma mulr_le0_ge0 x y : x <= 0 -> 0 <= y -> x * y <= 0.
proof: Proof. by move=> x_le0 y_le0; rewrite -(mulr0 x) ler_wnM2l. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)