proposition: Lemma mulR_gt0 x y : x > 0 -> y > 0 -> x * y > 0.
proof: Proof. by move=> xgt0 /(pmulR_rle0 _ xgt0). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)