simpl in |- *; split; auto with float.
case H; intros H1 (H2, H3); auto.
rewrite <- (Zabs_eq radix); auto with zarith.
rewrite <- Zabs_Zmult.
rewrite (fun x => Zabs_eq (Zabs x)); auto with float zarith.
case H; intros H1 (H2, H3); auto.
Qed.

Theorem FsubnormalUnique :
forall p q : float, Fsubnormal p -> Fsubnormal q -> p = q :>R -> p = q.