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