intros x H' H'0; unfold FSucc in |- *.
generalize (Z_eq_bool_correct (Fnum x) (pPred (vNum b)));
case (Z_eq_bool (Fnum x) (pPred (vNum b))); auto.
intros H'1; Contradict H'; auto.
intros H'1;
generalize (Z_eq_bool_correct (Fnum x) (- nNormMin radix precision));
case (Z_eq_bool (Fnum x) (- nNormMin radix precision));
auto.
intros H'2; Contradict H'0; auto.
Qed.

Theorem FSuccDiff1 :
forall x : float,
Fnum x <> (- nNormMin radix precision)%Z ->
Fminus radix (FSucc x) x = Float 1%nat (Fexp x) :>R.