proposition: Lemma leR_pmul2r x y z : x > 0 -> (y * x <= z * x <-> y <= z).
proof: Proof. by move=> x_gt0; rewrite -!(mulRC x); apply: leR_pmul2l x_gt0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)