proposition: Lemma lteifD2l C x : {mono +%R x : y z / y < z ?<= if C}.
proof: Proof. by case: C => ? ?; rewrite /= lterD2. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)