proposition: Lemma gtr_nMl x y : y < 0 -> (x * y < y) = (1 < x).
proof: Proof. by move=> hy; rewrite -{2}[y]mul1r ltr_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)