proposition: Lemma subr_lteifr0 C x y : (y - x < 0 ?<= if C) = (y < x ?<= if C).
proof: Proof. by case: C => /=; rewrite subr_lte0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)