proposition: Lemma subr_ge0 x y : (0 <= x - y) = (y <= x).
proof: Proof. by rewrite ge0_def -le_def. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)