proposition: Lemma subr_ge0 x y : (0 <= y - x) = (x <= y).
proof: Proof. exact: subr_ge0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)