[ O \Rightarrow O
| (S p) \Rightarrow p ].
-theorem pred_Sn : \forall n:nat.
-(eq nat n (pred (S n))).
+theorem pred_Sn : \forall n:nat.n=(pred (S n)).
intros; reflexivity.
qed.
apply eq_f. assumption.
qed.
-theorem inj_S : \forall n,m:nat.
-(eq nat (S n) (S m)) \to (eq nat n m)
+theorem inj_S : \forall n,m:nat.(S n)=(S m) \to n=m
\def injective_S.
theorem not_eq_S : \forall n,m:nat.
-Not (eq nat n m) \to Not (eq nat (S n) (S m)).
+Not (n=m) \to Not (S n = S m).
intros. simplify. intros.
apply H. apply injective_S. assumption.
qed.
[ O \Rightarrow False
| (S p) \Rightarrow True ].
-theorem not_eq_O_S : \forall n:nat. Not (eq nat O (S n)).
+theorem not_eq_O_S : \forall n:nat. Not (O=S n).
intros. simplify. intros.
cut (not_zero O).
exact Hcut.
rewrite > H.exact I.
qed.
-theorem not_eq_n_Sn : \forall n:nat. Not (eq nat n (S n)).
+theorem not_eq_n_Sn : \forall n:nat. Not (n=S n).
intros.elim n.
apply not_eq_O_S.
apply not_eq_S.assumption.