proposition: Lemma gec_leR_trans a x y : x >= a -> x <= y -> y >= a.
proof: Proof. by move=> leax lexy /lexy. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq order) mathcomp(ssralg ssrnum ssrint rat) fourcolor(real) Coq(Setoid Morphisms)