intros x H'; unfold FPred in |- *.
generalize (Z_eq_bool_correct (Fnum x) (- pPred (vNum b)));
case (Z_eq_bool (Fnum x) (- pPred (vNum b))); auto.
intros H'0; Contradict H'0; auto.
Qed.

Theorem FPredSimpl2 :
forall x : float,
Fnum x = nNormMin radix precision ->
Fexp x <> (- dExp b)%Z -> FPred x = Float (pPred (vNum b)) (Zpred (Fexp x)).