proposition: Lemma ler_real y x : x <= y -> (x \is real) = (y \is real).
proof: Proof. by move=> le_xy; rewrite -(addrNK x y) rpredDl ?lerB_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)