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