proposition: Lemma rleT_el a b: realp a -> realp b -> a <=r b \/ b <r a.
proof: Proof. move=> ar br; case: (rleT_ell ar br). - by move=> ->; left; BRo_tac. - by move => [pa _]; left. - by right. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)