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