unfold Deq in |- *; intros; rewrite (Dcompare_shift x y n); trivial.
Qed.

(* Specifications: *)
Lemma Deq_x_shift_x :
forall (x : diadic) (n : Z),
(0 <= n)%Z -> Deq x (Diadic (Dnum x * two_p n) (Dexp x - n)).