proposition: Lemma subr_comparable0 x y : (x - y >=< 0)%R = (x >=< y)%R.
proof: Proof. by rewrite /comparable subr_ge0 subr_le0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)