X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Flogic%2Fconnectives.ma;h=2848c08c5753086d5ffb5e9073c1b2687ee95bae;hb=69dc6031c9e0574fa7a74ced74deeb7f9ec5695b;hp=a8cba2b4a394f15584f779fc7749d713a94ad694;hpb=7f842db771e5c3a4e9dbefb56dd1005b229ed214;p=helm.git

diff --git a/helm/matita/library/logic/connectives.ma b/helm/matita/library/logic/connectives.ma
index a8cba2b4a..2848c08c5 100644
--- a/helm/matita/library/logic/connectives.ma
+++ b/helm/matita/library/logic/connectives.ma
@@ -56,7 +56,21 @@ inductive Or (A,B:Prop) : Prop \def
 (*CSC: the URI must disappear: there is a bug now *)
 interpretation "logical or" 'or x y =
   (cic:/matita/logic/connectives/Or.ind#xpointer(1/1) x y).
-   
+
+theorem Or_ind':
+ \forall A,B:Prop.
+  \forall P: A \lor B \to Prop.
+   (\forall p:A. P (or_introl ? ? p)) \to
+   (\forall q:B. P (or_intror ? ? q)) \to
+    \forall p:A \lor B. P p.
+ intros.
+ apply
+  ([\lambda p.P p]
+   match p with
+    [(or_introl p) \Rightarrow H p
+    |(or_intror q) \Rightarrow H1 q]).
+qed.
+
 definition decidable : Prop \to Prop \def \lambda A:Prop. A \lor \lnot A.
 
 inductive ex (A:Type) (P:A \to Prop) : Prop \def