proposition: Lemma pmulr_lle0 x y : 0 < x -> (y * x <= 0) = (y <= 0).
proof: Proof. by move=> x_gt0; rewrite mulrC pmulr_rle0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)