proposition: Lemma mule_gt0 x y : 0 < x -> 0 < y -> 0 < x * y.
proof: Proof. by rewrite !lt_def => /andP[? ?] /andP[? ?]; rewrite mule_neq0 ?mule_ge0. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed