proposition: Lemma comparabler0 x : (x >=< 0)%R = (x \is Num.real).
proof: Proof. by rewrite comparable_sym. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)