proposition: Lemma gtr_pMr x y : 0 < y -> (y * x < y) = (x < 1).
proof: Proof. by move=> hy; rewrite -{2}[y]mulr1 ltr_pM2l. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)