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diff --git a/theories/Bool/IfProp.v b/theories/Bool/IfProp.v
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+(************************************************************************)
+(*  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: IfProp.v,v 1.7.2.1 2004/07/16 19:31:03 herbelin Exp $ i*)
+
+Require Import Bool.
+
+Inductive IfProp (A B:Prop) : bool -> Prop :=
+  | Iftrue : A -> IfProp A B true
+  | Iffalse : B -> IfProp A B false.
+
+Hint Resolve Iftrue Iffalse: bool v62.
+
+Lemma Iftrue_inv : forall (A B:Prop) (b:bool), IfProp A B b -> b = true -> A.
+destruct 1; intros; auto with bool.
+case diff_true_false; auto with bool.
+Qed.
+
+Lemma Iffalse_inv :
+ forall (A B:Prop) (b:bool), IfProp A B b -> b = false -> B.
+destruct 1; intros; auto with bool.
+case diff_true_false; trivial with bool.
+Qed.
+
+Lemma IfProp_true : forall A B:Prop, IfProp A B true -> A.
+intros.
+inversion H.
+assumption.
+Qed.
+
+Lemma IfProp_false : forall A B:Prop, IfProp A B false -> B.
+intros.
+inversion H.
+assumption.
+Qed.
+
+Lemma IfProp_or : forall (A B:Prop) (b:bool), IfProp A B b -> A \/ B.
+destruct 1; auto with bool.
+Qed.
+
+Lemma IfProp_sum : forall (A B:Prop) (b:bool), IfProp A B b -> {A} + {B}.
+destruct b; intro H.
+left; inversion H; auto with bool.
+right; inversion H; auto with bool.
+Qed.
+\ No newline at end of file