unfold FSucc in |- *; simpl in |- *.
generalize (Z_eq_bool_correct (- nNormMin radix precision) (pPred (vNum b)));
case (Z_eq_bool (- nNormMin radix precision) (pPred (vNum b)));
auto.
intros H'1; absurd (0%nat <= pPred (vNum b))%Z; auto with zarith arith.
rewrite <- H'1.
unfold nNormMin in |- *; simpl in |- *; auto with zarith.
replace 0%Z with (- (0))%Z; auto with zarith.
unfold pPred in |- *; apply Zle_Zpred; auto with zarith.
intros H';
generalize
(Z_eq_bool_correct (- nNormMin radix precision)
(- nNormMin radix precision));
case (Z_eq_bool (- nNormMin radix precision) (- nNormMin radix precision)).
intros H'0; generalize (Z_eq_bool_correct (- dExp b) (- dExp b));
case (Z_eq_bool (- dExp b) (- dExp b)); auto.
intros H'1; Contradict H'1; auto.
intros H'1; Contradict H'1; auto.
Qed.

Theorem FSuccSimpl4 :
forall x : float,
Fnum x <> pPred (vNum b) ->
Fnum x <> (- nNormMin radix precision)%Z ->
FSucc x = Float (Zsucc (Fnum x)) (Fexp x).