1 files changed, 27 insertions, 0 deletions
diff --git a/theories7/Bool/DecBool.v b/theories7/Bool/DecBool.v
new file mode 100755
index 00000000..c22cd032
--- /dev/null
+++ b/theories7/Bool/DecBool.v
@@ -0,0 +1,27 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+(*i $Id: DecBool.v,v 1.1.2.1 2004/07/16 19:31:25 herbelin Exp $ i*)
+
+Set Implicit Arguments.
+
+Definition ifdec : (A,B:Prop)(C:Set)({A}+{B})->C->C->C
+   := [A,B,C,H,x,y]if H then [_]x else [_]y.
+
+
+Theorem ifdec_left : (A,B:Prop)(C:Set)(H:{A}+{B})~B->(x,y:C)(ifdec H x y)=x.
+Intros; Case H; Auto.
+Intro; Absurd B; Trivial.
+Qed.
+
+Theorem ifdec_right : (A,B:Prop)(C:Set)(H:{A}+{B})~A->(x,y:C)(ifdec H x y)=y.
+Intros; Case H; Auto.
+Intro; Absurd A; Trivial.
+Qed.
+
+Unset Implicit Arguments.