proposition: Lemma ger_nMl x y : y < 0 -> (x * y <= y) = (1 <= x).
proof: Proof. by move=> hy; rewrite -{2}[y]mul1r ler_nM2r. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)