proposition: Lemma sgz_int m : sgz (m%:~R : R) = sgz m.
proof: Proof. by rewrite /sgz intr_eq0 ltrz0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)