proposition: Lemma signr_le0 (b : bool) : ((-1) ^+ b <= 0 :> R) = b.
proof: Proof. by rewrite le_eqVlt signr_eq0 signr_lt0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)