proposition: Lemma dle0_muleDl x y z : y <= 0 -> z <= 0 -> (y + z) * x = y * x + z * x.
proof: Proof. by move=> *; rewrite !dual_addeE mulNe ge0_muleDl ?oppe_ge0 ?mulNe. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed