proposition: Lemma t2z_eqb_morph : forall x' y', Z.eqb (T2Z x') (T2Z y') = eqb x' y'.
proof: Proof. intros x y; unfold eqb. case_eq (Nat.eqb x y); [| rewrite <- 2 Bool.not_true_iff_false]; rewrite Z.eqb_eq; rewrite Nat.eqb_eq; rewrite Nat2Z.inj_iff; auto. Qed.
imports: ZArith NPeano