proposition: Lemma gtr_pMl x y : 0 < y -> (x * y < y) = (x < 1).
proof: Proof. by move=> hy; rewrite -{2}[y]mul1r ltr_pM2r. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)