proposition: Lemma Nreal_leF x y : y \is real -> x \notin real -> (x <= y) = false.
proof: Proof. by move=> yR; apply: contraNF=> /ler_real->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)