From 97fefe1fcca363a1317e066e7f4b99b9c1e9987b Mon Sep 17 00:00:00 2001
From: Stephane Glondu <steph@glondu.net>
Date: Thu, 12 Jan 2012 16:02:20 +0100
Subject: Imported Upstream version 8.4~beta

---
 theories/ZArith/Zmisc.v | 71 +++----------------------------------------------
 1 file changed, 4 insertions(+), 67 deletions(-)

(limited to 'theories/ZArith/Zmisc.v')

diff --git a/theories/ZArith/Zmisc.v b/theories/ZArith/Zmisc.v
index a8872bd5..ff844ec2 100644
--- a/theories/ZArith/Zmisc.v
+++ b/theories/ZArith/Zmisc.v
@@ -1,13 +1,11 @@
 (************************************************************************)
 (*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
-(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2011     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010     *)
 (*   \VV/  **************************************************************)
 (*    //   *      This file is distributed under the terms of the       *)
 (*         *       GNU Lesser General Public License Version 2.1        *)
 (************************************************************************)
 
-(*i $Id: Zmisc.v 14641 2011-11-06 11:59:10Z herbelin $ i*)
-
 Require Import Wf_nat.
 Require Import BinInt.
 Require Import Zcompare.
@@ -20,72 +18,11 @@ Open Local Scope Z_scope.
 
 (** [n]th iteration of the function [f] *)
 
-Fixpoint iter_pos (n:positive) (A:Type) (f:A -> A) (x:A) : A :=
-  match n with
-    | xH => f x
-    | xO n' => iter_pos n' A f (iter_pos n' A f x)
-    | xI n' => f (iter_pos n' A f (iter_pos n' A f x))
-  end.
-
-Definition iter (n:Z) (A:Type) (f:A -> A) (x:A) :=
-  match n with
-    | Z0 => x
-    | Zpos p => iter_pos p A f x
-    | Zneg p => x
-  end.
-
-Theorem iter_nat_of_P :
-  forall (p:positive) (A:Type) (f:A -> A) (x:A),
-    iter_pos p A f x = iter_nat (nat_of_P p) A f x.
-Proof.
-  intro n; induction n as [p H| p H| ];
-    [ intros; simpl in |- *; rewrite (H A f x);
-      rewrite (H A f (iter_nat (nat_of_P p) A f x));
-	rewrite (ZL6 p); symmetry  in |- *; apply f_equal with (f := f);
-	  apply iter_nat_plus
-      | intros; unfold nat_of_P in |- *; simpl in |- *; rewrite (H A f x);
-	rewrite (H A f (iter_nat (nat_of_P p) A f x));
-	  rewrite (ZL6 p); symmetry  in |- *; apply iter_nat_plus
-      | simpl in |- *; auto with arith ].
-Qed.
+Notation iter := @Z.iter (only parsing).
 
 Lemma iter_nat_of_Z : forall n A f x, 0 <= n ->
-  iter n A f x = iter_nat (Zabs_nat n) A f x.
+  iter n A f x = iter_nat (Z.abs_nat n) A f x.
 intros n A f x; case n; auto.
-intros p _; unfold iter, Zabs_nat; apply iter_nat_of_P.
+intros p _; unfold Z.iter, Z.abs_nat; apply iter_nat_of_P.
 intros p abs; case abs; trivial.
 Qed.
-
-Theorem iter_pos_plus :
-  forall (p q:positive) (A:Type) (f:A -> A) (x:A),
-    iter_pos (p + q) A f x = iter_pos p A f (iter_pos q A f x).
-Proof.
-  intros n m; intros.
-  rewrite (iter_nat_of_P m A f x).
-  rewrite (iter_nat_of_P n A f (iter_nat (nat_of_P m) A f x)).
-  rewrite (iter_nat_of_P (n + m) A f x).
-  rewrite (nat_of_P_plus_morphism n m).
-  apply iter_nat_plus.
-Qed.
-
-(** Preservation of invariants : if [f : A->A] preserves the invariant [Inv],
-    then the iterates of [f] also preserve it. *)
-
-Theorem iter_nat_invariant :
-  forall (n:nat) (A:Type) (f:A -> A) (Inv:A -> Prop),
-    (forall x:A, Inv x -> Inv (f x)) ->
-    forall x:A, Inv x -> Inv (iter_nat n A f x).
-Proof.
-  simple induction n; intros;
-    [ trivial with arith
-      | simpl in |- *; apply H0 with (x := iter_nat n0 A f x); apply H;
-	trivial with arith ].
-Qed.
-
-Theorem iter_pos_invariant :
-  forall (p:positive) (A:Type) (f:A -> A) (Inv:A -> Prop),
-    (forall x:A, Inv x -> Inv (f x)) ->
-    forall x:A, Inv x -> Inv (iter_pos p A f x).
-Proof.
-  intros; rewrite iter_nat_of_P; apply iter_nat_invariant; trivial with arith.
-Qed.
-- 
cgit v1.2.3