proposition: Fact lez_mul m n : lez 0 m -> lez 0 n -> lez 0 (m * n).
proof: Proof. by case: m n => [] m [] n. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)