proposition: Lemma ltr_pdivlMr z x y : 0 < z -> (x < y / z) = (x * z < y).
proof: Proof. by move=> z_gt0; rewrite -(@ltr_pM2r _ z _ x) ?mulfVK ?gt_eqF. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)