X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Fnat%2Fnat.ma;h=e36c1beaa95303f52e693f11e4ac7f3d913b6928;hb=5c6b8eec9db4119a87eb4fd4055f1ac31a713d90;hp=df045daa732e5310d93245c2164610c74d350ae8;hpb=03fcee16d9c262aad38a47d0a409b684a965cc3f;p=helm.git

diff --git a/helm/matita/library/nat/nat.ma b/helm/matita/library/nat/nat.ma
index df045daa7..e36c1beaa 100644
--- a/helm/matita/library/nat/nat.ma
+++ b/helm/matita/library/nat/nat.ma
@@ -14,9 +14,6 @@
 
 set "baseuri" "cic:/matita/nat/nat".
 
-include "logic/equality.ma".
-include "logic/connectives.ma".
-include "datatypes/bool.ma".
 include "higher_order_defs/functions.ma".
 
 inductive nat : Set \def
@@ -29,7 +26,7 @@ definition pred: nat \to nat \def
 | (S p) \Rightarrow p ].
 
 theorem pred_Sn : \forall n:nat.n=(pred (S n)).
-intros; reflexivity.
+intros. reflexivity.
 qed.
 
 theorem injective_S : injective nat nat S.
@@ -44,7 +41,7 @@ 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. 
-\lnot n=m \to \lnot (S n = S m).
+\lnot n=m \to S n \neq S m.
 intros. simplify. intros.
 apply H. apply injective_S. assumption.
 qed.
@@ -55,14 +52,14 @@ definition not_zero : nat \to Prop \def
   [ O \Rightarrow False
   | (S p) \Rightarrow True ].
 
-theorem not_eq_O_S : \forall n:nat. \lnot O=S n.
+theorem not_eq_O_S : \forall n:nat. O \neq S n.
 intros. simplify. intros.
 cut (not_zero O).
 exact Hcut.
 rewrite > H.exact I.
 qed.
 
-theorem not_eq_n_Sn : \forall n:nat. \lnot n=S n.
+theorem not_eq_n_Sn : \forall n:nat. n \neq S n.
 intros.elim n.
 apply not_eq_O_S.
 apply not_eq_S.assumption.
@@ -74,6 +71,14 @@ P O \to  (\forall m:nat. P (S m)) \to P n.
 intros.elim n.assumption.apply H1.
 qed.
 
+theorem nat_case1:
+\forall n:nat.\forall P:nat \to Prop. 
+(n=O \to P O) \to  (\forall m:nat. (n=(S m) \to P (S m))) \to P n.
+intros 2.elim n.
+apply H.reflexivity.
+apply H2.reflexivity.
+qed.
+
 theorem nat_elim2 :
 \forall R:nat \to nat \to Prop.
 (\forall n:nat. R O n) \to 
@@ -92,7 +97,7 @@ intro.elim n1.
 left.reflexivity.
 right.apply not_eq_O_S.
 intro.right.intro.
-apply not_eq_O_S n1 ?.
+apply not_eq_O_S n1.
 apply sym_eq.assumption.
 intros.elim H.
 left.apply eq_f. assumption.