X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Fdatatypes%2Fbool.ma;h=f4aec8167476b0d88204a06d3d23aaa798a323ac;hb=c5e94d35e8f36f868c5a1f02d80a419bfe802ba1;hp=a4667da30249730b98bc4f39c522dd824a180019;hpb=69dc6031c9e0574fa7a74ced74deeb7f9ec5695b;p=helm.git

diff --git a/helm/matita/library/datatypes/bool.ma b/helm/matita/library/datatypes/bool.ma
index a4667da30..f4aec8167 100644
--- a/helm/matita/library/datatypes/bool.ma
+++ b/helm/matita/library/datatypes/bool.ma
@@ -19,9 +19,20 @@ include "logic/equality.ma".
 inductive bool : Set \def 
   | true : bool
   | false : bool.
-  
+
+theorem bool_elim: \forall P:bool \to Prop. \forall b:bool.
+  (b = true \to P true)
+  \to (b = false \to P false)
+  \to P b.
+  intros 2 (P b).
+  elim b;
+  [ apply H; reflexivity
+  | apply H1; reflexivity
+  ]
+qed.
+
 theorem not_eq_true_false : true \neq false.
-simplify.intro.
+unfold Not.intro.
 change with 
 match true with
 [ true \Rightarrow False