proposition: Lemma eqR_le2 x y : x == y <-> x <= y <= x.
proof: Proof. by []. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)