proposition: Lemma CRplus_le_compat_r : forall {R : ConstructiveReals} (r r1 r2 : CRcarrier R), r1 <= r2 -> r1 + r <= r2 + r.
proof: Proof. intros. intros abs. apply CRplus_lt_reg_r in abs. apply H. exact abs. Qed.
imports: QArith Qabs Qround