Imported Upstream version 8.4~betaupstream/8.4_beta

1 files changed, 66 insertions, 391 deletions

diff --git a/theories/ZArith/Zcompare.v b/theories/ZArith/Zcompare.v
index ae5302ee..20e1b006 100644
--- a/theories/ZArith/Zcompare.v
+++ b/theories/ZArith/Zcompare.v
@@ -1,387 +1,91 @@
 (* -*- coding: utf-8 -*- *)
 (************************************************************************)
 (*  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 $$ i*)
+(** Binary Integers : results about Zcompare *)
+(** Initial author: Pierre Crégut (CNET, Lannion, France *)
 
-(**********************************************************************)
-(** Binary Integers (Pierre Crégut, CNET, Lannion, France)            *)
-(**********************************************************************)
+(** THIS FILE IS DEPRECATED.
+    It is now almost entirely made of compatibility formulations
+    for results already present in BinInt.Z. *)
 
-Require Export BinPos.
-Require Export BinInt.
-Require Import Lt.
-Require Import Gt.
-Require Import Plus.
-Require Import Mult.
+Require Export BinPos BinInt.
+Require Import Lt Gt Plus Mult. (* Useless now, for compatibility only *)
 
-Open Local Scope Z_scope.
+Local Open Scope Z_scope.
 
 (***************************)
 (** * Comparison on integers *)
 
-Lemma Zcompare_refl : forall n:Z, (n ?= n) = Eq.
-Proof.
-  intro x; destruct x as [| p| p]; simpl in |- *;
-    [ reflexivity | apply Pcompare_refl | rewrite Pcompare_refl; reflexivity ].
-Qed.
-
-Lemma Zcompare_Eq_eq : forall n m:Z, (n ?= m) = Eq -> n = m.
-Proof.
-  intros x y; destruct x as [| x'| x']; destruct y as [| y'| y']; simpl in |- *;
-    intro H; reflexivity || (try discriminate H);
-      [ rewrite (Pcompare_Eq_eq x' y' H); reflexivity
-	| rewrite (Pcompare_Eq_eq x' y');
-	  [ reflexivity
-	    | destruct ((x' ?= y')%positive Eq); reflexivity || discriminate ] ].
-Qed.
-
-Ltac destr_zcompare :=
- match goal with |- context [Zcompare ?x ?y] =>
-  let H := fresh "H" in
-  case_eq (Zcompare x y); intro H;
-   [generalize (Zcompare_Eq_eq _ _ H); clear H; intro H |
-    change (x<y)%Z in H |
-    change (x>y)%Z in H ]
- end.
-
-Lemma Zcompare_Eq_iff_eq : forall n m:Z, (n ?= m) = Eq <-> n = m.
-Proof.
-  intros x y; split; intro E;
-    [ apply Zcompare_Eq_eq; assumption | rewrite E; apply Zcompare_refl ].
-Qed.
-
-Lemma Zcompare_antisym : forall n m:Z, CompOpp (n ?= m) = (m ?= n).
-Proof.
-  intros x y; destruct x; destruct y; simpl in |- *;
-    reflexivity || discriminate H || rewrite Pcompare_antisym;
-      reflexivity.
-Qed.
-
 Lemma Zcompare_Gt_Lt_antisym : forall n m:Z, (n ?= m) = Gt <-> (m ?= n) = Lt.
-Proof.
-  intros x y.
-  rewrite <- Zcompare_antisym. change Gt with (CompOpp Lt).
-  split.
-  auto using CompOpp_inj.
-  intros; f_equal; auto.
-Qed.
-
-Lemma Zcompare_spec : forall n m, CompSpec eq Zlt n m (n ?= m).
-Proof.
-  intros.
-  destruct (n?=m) as [ ]_eqn:H; constructor; auto.
-  apply Zcompare_Eq_eq; auto.
-  red; rewrite <- Zcompare_antisym, H; auto.
-Qed.
+Proof Z.gt_lt_iff.
 
+Lemma Zcompare_antisym n m : CompOpp (n ?= m) = (m ?= n).
+Proof eq_sym (Z.compare_antisym n m).
 
 (** * Transitivity of comparison *)
 
 Lemma Zcompare_Lt_trans :
   forall n m p:Z, (n ?= m) = Lt -> (m ?= p) = Lt -> (n ?= p) = Lt.
-Proof.
-  intros x y z; case x; case y; case z; simpl;
-    try discriminate; auto with arith.
-  intros; eapply Plt_trans; eauto.
-  intros p q r; rewrite 3 Pcompare_antisym; simpl.
-  intros; eapply Plt_trans; eauto.
-Qed.
+Proof Z.lt_trans.
 
 Lemma Zcompare_Gt_trans :
   forall n m p:Z, (n ?= m) = Gt -> (m ?= p) = Gt -> (n ?= p) = Gt.
 Proof.
-  intros n m p Hnm Hmp.
-  apply <- Zcompare_Gt_Lt_antisym.
-  apply -> Zcompare_Gt_Lt_antisym in Hnm.
-  apply -> Zcompare_Gt_Lt_antisym in Hmp.
-  eapply Zcompare_Lt_trans; eauto.
+ intros n m p. change (n > m -> m > p -> n > p).
+ Z.swap_greater. intros. now transitivity m.
 Qed.
 
 (** * Comparison and opposite *)
 
-Lemma Zcompare_opp : forall n m:Z, (n ?= m) = (- m ?= - n).
+Lemma Zcompare_opp n m : (n ?= m) = (- m ?= - n).
 Proof.
-  intros x y; case x; case y; simpl in |- *; auto with arith; intros;
-    rewrite <- ZC4; trivial with arith.
+ symmetry. apply Z.compare_opp.
 Qed.
 
-Hint Local Resolve Pcompare_refl.
-
 (** * Comparison first-order specification *)
 
-Lemma Zcompare_Gt_spec :
-  forall n m:Z, (n ?= m) = Gt ->  exists h : positive, n + - m = Zpos h.
+Lemma Zcompare_Gt_spec n m : (n ?= m) = Gt ->  exists h, n + - m = Zpos h.
 Proof.
-  intros x y; case x; case y;
-    [ simpl in |- *; intros H; discriminate H
-      | simpl in |- *; intros p H; discriminate H
-      | intros p H; exists p; simpl in |- *; auto with arith
-      | intros p H; exists p; simpl in |- *; auto with arith
-      | intros q p H; exists (p - q)%positive; unfold Zplus, Zopp in |- *;
-	unfold Zcompare in H; rewrite H; trivial with arith
-      | intros q p H; exists (p + q)%positive; simpl in |- *; trivial with arith
-      | simpl in |- *; intros p H; discriminate H
-      | simpl in |- *; intros q p H; discriminate H
-      | unfold Zcompare in |- *; intros q p; rewrite <- ZC4; intros H;
-	exists (q - p)%positive; simpl in |- *; rewrite (ZC1 q p H);
-	  trivial with arith ].
+ rewrite Z.compare_sub. unfold Z.sub.
+ destruct (n+-m) as [|p|p]; try discriminate. now exists p.
 Qed.
 
 (** * Comparison and addition *)
 
-Lemma weaken_Zcompare_Zplus_compatible :
-  (forall (n m:Z) (p:positive), (Zpos p + n ?= Zpos p + m) = (n ?= m)) ->
-  forall n m p:Z, (p + n ?= p + m) = (n ?= m).
+Lemma Zcompare_plus_compat n m p : (p + n ?= p + m) = (n ?= m).
 Proof.
-  intros H x y z; destruct z;
-    [ reflexivity
-      | apply H
-      | rewrite (Zcompare_opp x y); rewrite Zcompare_opp;
-	do 2 rewrite Zopp_plus_distr; rewrite Zopp_neg;
-	  apply H ].
+ apply Z.add_compare_mono_l.
 Qed.
 
-Hint Local Resolve ZC4.
-
-Lemma weak_Zcompare_Zplus_compatible :
-  forall (n m:Z) (p:positive), (Zpos p + n ?= Zpos p + m) = (n ?= m).
-Proof.
-  intros x y z; case x; case y; simpl in |- *; auto with arith;
-    [ intros p; apply nat_of_P_lt_Lt_compare_complement_morphism; apply ZL17
-      | intros p; ElimPcompare z p; intros E; rewrite E; auto with arith;
-	apply nat_of_P_gt_Gt_compare_complement_morphism;
-	  rewrite nat_of_P_minus_morphism;
-	    [ unfold gt in |- *; apply ZL16 | assumption ]
-      | intros p; ElimPcompare z p; intros E; auto with arith;
-	apply nat_of_P_gt_Gt_compare_complement_morphism;
-	  unfold gt in |- *; apply ZL17
-      | intros p q; ElimPcompare q p; intros E; rewrite E;
-	[ rewrite (Pcompare_Eq_eq q p E); apply Pcompare_refl
-	  | apply nat_of_P_lt_Lt_compare_complement_morphism;
-	    do 2 rewrite nat_of_P_plus_morphism; apply plus_lt_compat_l;
-	      apply nat_of_P_lt_Lt_compare_morphism with (1 := E)
-	  | apply nat_of_P_gt_Gt_compare_complement_morphism; unfold gt in |- *;
-	    do 2 rewrite nat_of_P_plus_morphism; apply plus_lt_compat_l;
-	      exact (nat_of_P_gt_Gt_compare_morphism q p E) ]
-      | intros p q; ElimPcompare z p; intros E; rewrite E; auto with arith;
-	apply nat_of_P_gt_Gt_compare_complement_morphism;
-	  rewrite nat_of_P_minus_morphism;
-	    [ unfold gt in |- *; apply lt_trans with (m := nat_of_P z);
-	      [ apply ZL16 | apply ZL17 ]
-	      | assumption ]
-      | intros p; ElimPcompare z p; intros E; rewrite E; auto with arith;
-	simpl in |- *; apply nat_of_P_lt_Lt_compare_complement_morphism;
-	  rewrite nat_of_P_minus_morphism; [ apply ZL16 | assumption ]
-      | intros p q; ElimPcompare z q; intros E; rewrite E; auto with arith;
-	simpl in |- *; apply nat_of_P_lt_Lt_compare_complement_morphism;
-	  rewrite nat_of_P_minus_morphism;
-	    [ apply lt_trans with (m := nat_of_P z); [ apply ZL16 | apply ZL17 ]
-	      | assumption ]
-      | intros p q; ElimPcompare z q; intros E0; rewrite E0; ElimPcompare z p;
-	intros E1; rewrite E1; ElimPcompare q p; intros E2;
-	  rewrite E2; auto with arith;
-	    [ absurd ((q ?= p)%positive Eq = Lt);
-	      [ rewrite <- (Pcompare_Eq_eq z q E0);
-		rewrite <- (Pcompare_Eq_eq z p E1); rewrite (Pcompare_refl z);
-		  discriminate
-		| assumption ]
-	      | absurd ((q ?= p)%positive Eq = Gt);
-		[ rewrite <- (Pcompare_Eq_eq z q E0);
-		  rewrite <- (Pcompare_Eq_eq z p E1); rewrite (Pcompare_refl z);
-		    discriminate
-		  | assumption ]
-	      | absurd ((z ?= p)%positive Eq = Lt);
-		[ rewrite (Pcompare_Eq_eq z q E0); rewrite <- (Pcompare_Eq_eq q p E2);
-		  rewrite (Pcompare_refl q); discriminate
-		  | assumption ]
-	      | absurd ((z ?= p)%positive Eq = Lt);
-		[ rewrite (Pcompare_Eq_eq z q E0); rewrite E2; discriminate
-		  | assumption ]
-	      | absurd ((z ?= p)%positive Eq = Gt);
-		[ rewrite (Pcompare_Eq_eq z q E0); rewrite <- (Pcompare_Eq_eq q p E2);
-		  rewrite (Pcompare_refl q); discriminate
-		  | assumption ]
-	      | absurd ((z ?= p)%positive Eq = Gt);
-		[ rewrite (Pcompare_Eq_eq z q E0); rewrite E2; discriminate
-		  | assumption ]
-	      | absurd ((z ?= q)%positive Eq = Lt);
-		[ rewrite (Pcompare_Eq_eq z p E1); rewrite (Pcompare_Eq_eq q p E2);
-		  rewrite (Pcompare_refl p); discriminate
-		  | assumption ]
-	      | absurd ((p ?= q)%positive Eq = Gt);
-		[ rewrite <- (Pcompare_Eq_eq z p E1); rewrite E0; discriminate
-		  | apply ZC2; assumption ]
-	      | simpl in |- *; rewrite (Pcompare_Eq_eq q p E2);
-		rewrite (Pcompare_refl (p - z)); auto with arith
-	      | simpl in |- *; rewrite <- ZC4;
-		apply nat_of_P_gt_Gt_compare_complement_morphism;
-		  rewrite nat_of_P_minus_morphism;
-		    [ rewrite nat_of_P_minus_morphism;
-		      [ unfold gt in |- *; apply plus_lt_reg_l with (p := nat_of_P z);
-			rewrite le_plus_minus_r;
-			  [ rewrite le_plus_minus_r;
-			    [ apply nat_of_P_lt_Lt_compare_morphism; assumption
-			      | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-				assumption ]
-			    | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-			      assumption ]
-			| apply ZC2; assumption ]
-		      | apply ZC2; assumption ]
-	      | simpl in |- *; rewrite <- ZC4;
-		apply nat_of_P_lt_Lt_compare_complement_morphism;
-		  rewrite nat_of_P_minus_morphism;
-		    [ rewrite nat_of_P_minus_morphism;
-		      [ apply plus_lt_reg_l with (p := nat_of_P z);
-			rewrite le_plus_minus_r;
-			  [ rewrite le_plus_minus_r;
-			    [ apply nat_of_P_lt_Lt_compare_morphism; apply ZC1;
-			      assumption
-			      | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-				assumption ]
-			    | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-			      assumption ]
-			| apply ZC2; assumption ]
-		      | apply ZC2; assumption ]
-	      | absurd ((z ?= q)%positive Eq = Lt);
-		[ rewrite (Pcompare_Eq_eq q p E2); rewrite E1; discriminate
-		  | assumption ]
-	      | absurd ((q ?= p)%positive Eq = Lt);
-		[ cut ((q ?= p)%positive Eq = Gt);
-		  [ intros E; rewrite E; discriminate
-		    | apply nat_of_P_gt_Gt_compare_complement_morphism;
-		      unfold gt in |- *; apply lt_trans with (m := nat_of_P z);
-			[ apply nat_of_P_lt_Lt_compare_morphism; apply ZC1; assumption
-			  | apply nat_of_P_lt_Lt_compare_morphism; assumption ] ]
-		  | assumption ]
-	      | absurd ((z ?= q)%positive Eq = Gt);
-		[ rewrite (Pcompare_Eq_eq z p E1); rewrite (Pcompare_Eq_eq q p E2);
-		  rewrite (Pcompare_refl p); discriminate
-		  | assumption ]
-	      | absurd ((z ?= q)%positive Eq = Gt);
-		[ rewrite (Pcompare_Eq_eq z p E1); rewrite ZC1;
-		  [ discriminate | assumption ]
-		  | assumption ]
-	      | absurd ((z ?= q)%positive Eq = Gt);
-		[ rewrite (Pcompare_Eq_eq q p E2); rewrite E1; discriminate
-		  | assumption ]
-	      | absurd ((q ?= p)%positive Eq = Gt);
-		[ rewrite ZC1;
-		  [ discriminate
-		    | apply nat_of_P_gt_Gt_compare_complement_morphism;
-		      unfold gt in |- *; apply lt_trans with (m := nat_of_P z);
-			[ apply nat_of_P_lt_Lt_compare_morphism; apply ZC1; assumption
-			  | apply nat_of_P_lt_Lt_compare_morphism; assumption ] ]
-		  | assumption ]
-	      | simpl in |- *; rewrite (Pcompare_Eq_eq q p E2); apply Pcompare_refl
-	      | simpl in |- *; apply nat_of_P_gt_Gt_compare_complement_morphism;
-		unfold gt in |- *; rewrite nat_of_P_minus_morphism;
-		  [ rewrite nat_of_P_minus_morphism;
-		    [ apply plus_lt_reg_l with (p := nat_of_P p);
-		      rewrite le_plus_minus_r;
-			[ rewrite plus_comm; apply plus_lt_reg_l with (p := nat_of_P q);
-			  rewrite plus_assoc; rewrite le_plus_minus_r;
-			    [ rewrite (plus_comm (nat_of_P q)); apply plus_lt_compat_l;
-			      apply nat_of_P_lt_Lt_compare_morphism;
-				assumption
-			      | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-				apply ZC1; assumption ]
-			  | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-			    apply ZC1; assumption ]
-		      | assumption ]
-		    | assumption ]
-	      | simpl in |- *; apply nat_of_P_lt_Lt_compare_complement_morphism;
-		rewrite nat_of_P_minus_morphism;
-		  [ rewrite nat_of_P_minus_morphism;
-		    [ apply plus_lt_reg_l with (p := nat_of_P q);
-		      rewrite le_plus_minus_r;
-			[ rewrite plus_comm; apply plus_lt_reg_l with (p := nat_of_P p);
-			  rewrite plus_assoc; rewrite le_plus_minus_r;
-			    [ rewrite (plus_comm (nat_of_P p)); apply plus_lt_compat_l;
-			      apply nat_of_P_lt_Lt_compare_morphism;
-				apply ZC1; assumption
-			      | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-				apply ZC1; assumption ]
-			  | apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
-			    apply ZC1; assumption ]
-		      | assumption ]
-		    | assumption ] ] ].
-Qed.
-
-Lemma Zcompare_plus_compat : forall n m p:Z, (p + n ?= p + m) = (n ?= m).
+Lemma Zplus_compare_compat (r:comparison) (n m p q:Z) :
+  (n ?= m) = r -> (p ?= q) = r -> (n + p ?= m + q) = r.
 Proof.
-  exact (weaken_Zcompare_Zplus_compatible weak_Zcompare_Zplus_compatible).
+ rewrite (Z.compare_sub n), (Z.compare_sub p), (Z.compare_sub (n+p)).
+ unfold Z.sub. rewrite Z.opp_add_distr. rewrite Z.add_shuffle1.
+ destruct (n+-m), (p+-q); simpl; intros; now subst.
 Qed.
 
-Lemma Zplus_compare_compat :
-  forall (r:comparison) (n m p q:Z),
-    (n ?= m) = r -> (p ?= q) = r -> (n + p ?= m + q) = r.
+Lemma Zcompare_succ_Gt n : (Z.succ n ?= n) = Gt.
 Proof.
-  intros r x y z t; case r;
-    [ intros H1 H2; elim (Zcompare_Eq_iff_eq x y); elim (Zcompare_Eq_iff_eq z t);
-      intros H3 H4 H5 H6; rewrite H3;
-	[ rewrite H5;
-	  [ elim (Zcompare_Eq_iff_eq (y + t) (y + t)); auto with arith
-	    | auto with arith ]
-	  | auto with arith ]
-      | intros H1 H2; elim (Zcompare_Gt_Lt_antisym (y + t) (x + z)); intros H3 H4;
-	apply H3; apply Zcompare_Gt_trans with (m := y + z);
-	  [ rewrite Zcompare_plus_compat; elim (Zcompare_Gt_Lt_antisym t z);
-	    auto with arith
-	    | do 2 rewrite <- (Zplus_comm z); rewrite Zcompare_plus_compat;
-	      elim (Zcompare_Gt_Lt_antisym y x); auto with arith ]
-      | intros H1 H2; apply Zcompare_Gt_trans with (m := x + t);
-	[ rewrite Zcompare_plus_compat; assumption
-	  | do 2 rewrite <- (Zplus_comm t); rewrite Zcompare_plus_compat;
-	    assumption ] ].
+ apply Z.lt_gt. apply Z.lt_succ_diag_r.
 Qed.
 
-Lemma Zcompare_succ_Gt : forall n:Z, (Zsucc n ?= n) = Gt.
+Lemma Zcompare_Gt_not_Lt n m : (n ?= m) = Gt <-> (n ?= m+1) <> Lt.
 Proof.
-  intro x; unfold Zsucc in |- *; pattern x at 2 in |- *;
-    rewrite <- (Zplus_0_r x); rewrite Zcompare_plus_compat;
-      reflexivity.
-Qed.
-
-Lemma Zcompare_Gt_not_Lt : forall n m:Z, (n ?= m) = Gt <-> (n ?= m + 1) <> Lt.
-Proof.
-  intros x y; split;
-    [ intro H; elim_compare x (y + 1);
-      [ intro H1; rewrite H1; discriminate
-	| intros H1; elim Zcompare_Gt_spec with (1 := H); intros h H2;
-	  absurd ((nat_of_P h > 0)%nat /\ (nat_of_P h < 1)%nat);
-	    [ unfold not in |- *; intros H3; elim H3; intros H4 H5;
-              absurd (nat_of_P h > 0)%nat;
-		[ unfold gt in |- *; apply le_not_lt; apply le_S_n; exact H5
-		  | assumption ]
-	      | split;
-		[ elim (ZL4 h); intros i H3; rewrite H3; apply gt_Sn_O
-		  | change (nat_of_P h < nat_of_P 1)%nat in |- *;
-		    apply nat_of_P_lt_Lt_compare_morphism;
-		      change ((Zpos h ?= 1) = Lt) in |- *; rewrite <- H2;
-			rewrite <- (fun m n:Z => Zcompare_plus_compat m n y);
-			  rewrite (Zplus_comm x); rewrite Zplus_assoc;
-			    rewrite Zplus_opp_r; simpl in |- *; exact H1 ] ]
-	| intros H1; rewrite H1; discriminate ]
-      | intros H; elim_compare x (y + 1);
-	[ intros H1; elim (Zcompare_Eq_iff_eq x (y + 1)); intros H2 H3;
-	  rewrite (H2 H1); exact (Zcompare_succ_Gt y)
-	  | intros H1; absurd ((x ?= y + 1) = Lt); assumption
-	  | intros H1; apply Zcompare_Gt_trans with (m := Zsucc y);
-	    [ exact H1 | exact (Zcompare_succ_Gt y) ] ] ].
+ change (n > m <-> n >= m+1). Z.swap_greater. symmetry. apply Z.le_succ_l.
 Qed.
 
 (** * Successor and comparison *)
 
-Lemma Zcompare_succ_compat : forall n m:Z, (Zsucc n ?= Zsucc m) = (n ?= m).
+Lemma Zcompare_succ_compat n m : (Z.succ n ?= Z.succ m) = (n ?= m).
 Proof.
-  intros n m; unfold Zsucc in |- *; do 2 rewrite (fun t:Z => Zplus_comm t 1);
-    rewrite Zcompare_plus_compat; auto with arith.
+ rewrite <- 2 Z.add_1_l. apply Zcompare_plus_compat.
 Qed.
 
 (** * Multiplication and comparison *)
@@ -389,28 +93,24 @@ Qed.
 Lemma Zcompare_mult_compat :
   forall (p:positive) (n m:Z), (Zpos p * n ?= Zpos p * m) = (n ?= m).
 Proof.
-  intros x; induction x as [p H| p H| ];
-    [ intros y z; cut (Zpos (xI p) = Zpos p + Zpos p + 1);
-      [ intros E; rewrite E; do 4 rewrite Zmult_plus_distr_l;
-	do 2 rewrite Zmult_1_l; apply Zplus_compare_compat;
-	  [ apply Zplus_compare_compat; apply H | trivial with arith ]
-	| simpl in |- *; rewrite (Pplus_diag p); trivial with arith ]
-      | intros y z; cut (Zpos (xO p) = Zpos p + Zpos p);
-	[ intros E; rewrite E; do 2 rewrite Zmult_plus_distr_l;
-	  apply Zplus_compare_compat; apply H
-	  | simpl in |- *; rewrite (Pplus_diag p); trivial with arith ]
-      | intros y z; do 2 rewrite Zmult_1_l; trivial with arith ].
+ intros p [|n|n] [|m|m]; simpl; trivial; now rewrite Pos.mul_compare_mono_l.
 Qed.
 
+Lemma Zmult_compare_compat_l n m p:
+  p > 0 -> (n ?= m) = (p * n ?= p * m).
+Proof.
+ intros; destruct p; try discriminate.
+ symmetry. apply Zcompare_mult_compat.
+Qed.
 
-(** * Reverting [x ?= y] to trichotomy *)
-
-Lemma rename :
-  forall (A:Type) (P:A -> Prop) (x:A), (forall y:A, x = y -> P y) -> P x.
+Lemma Zmult_compare_compat_r n m p :
+  p > 0 -> (n ?= m) = (n * p ?= m * p).
 Proof.
-  auto with arith.
+ intros; rewrite 2 (Zmult_comm _ p); now apply Zmult_compare_compat_l.
 Qed.
 
+(** * Relating [x ?= y] to [=], [<=], [<], [>=] or [>] *)
+
 Lemma Zcompare_elim :
   forall (c1 c2 c3:Prop) (n m:Z),
     (n = m -> c1) ->
@@ -421,11 +121,7 @@ Lemma Zcompare_elim :
                        | Gt => c3
                      end.
 Proof.
-  intros c1 c2 c3 x y; intros.
-  apply rename with (x := x ?= y); intro r; elim r;
-    [ intro; apply H; apply (Zcompare_Eq_eq x y); assumption
-      | unfold Zlt in H0; assumption
-      | unfold Zgt in H1; assumption ].
+ intros. case Z.compare_spec; trivial. now Z.swap_greater.
 Qed.
 
 Lemma Zcompare_eq_case :
@@ -436,26 +132,9 @@ Lemma Zcompare_eq_case :
                      | Gt => c3
                    end.
 Proof.
-  intros c1 c2 c3 x y; intros.
-  rewrite H0; rewrite Zcompare_refl.
-  assumption.
+ intros. subst. now rewrite Z.compare_refl.
 Qed.
 
-(** * Decompose an egality between two [?=] relations into 3 implications *)
-
-Lemma Zcompare_egal_dec :
-  forall n m p q:Z,
-    (n < m -> p < q) ->
-    ((n ?= m) = Eq -> (p ?= q) = Eq) ->
-    (n > m -> p > q) -> (n ?= m) = (p ?= q).
-Proof.
-  intros x1 y1 x2 y2.
-  unfold Zgt in |- *; unfold Zlt in |- *; case (x1 ?= y1); case (x2 ?= y2);
-    auto with arith; symmetry  in |- *; auto with arith.
-Qed.
-
-(** * Relating [x ?= y] to [Zle], [Zlt], [Zge] or [Zgt] *)
-
 Lemma Zle_compare :
   forall n m:Z,
     n <= m -> match n ?= m with
@@ -464,7 +143,7 @@ Lemma Zle_compare :
 		| Gt => False
               end.
 Proof.
-  intros x y; unfold Zle in |- *; elim (x ?= y); auto with arith.
+  intros. case Z.compare_spec; trivial; Z.order.
 Qed.
 
 Lemma Zlt_compare :
@@ -475,8 +154,7 @@ Lemma Zlt_compare :
               | Gt => False
             end.
 Proof.
-  intros x y; unfold Zlt in |- *; elim (x ?= y); intros;
-    discriminate || trivial with arith.
+  intros x y H; now rewrite H.
 Qed.
 
 Lemma Zge_compare :
@@ -487,7 +165,7 @@ Lemma Zge_compare :
 		| Gt => True
               end.
 Proof.
-  intros x y; unfold Zge in |- *; elim (x ?= y); auto with arith.
+  intros. now case Z.compare_spec.
 Qed.
 
 Lemma Zgt_compare :
@@ -498,26 +176,23 @@ Lemma Zgt_compare :
                | Gt => True
              end.
 Proof.
-  intros x y; unfold Zgt in |- *; elim (x ?= y); intros;
-    discriminate || trivial with arith.
+  intros x y H; now rewrite H.
 Qed.
 
-(*********************)
-(** * Other properties *)
+(** Compatibility notations *)
 
-Lemma Zmult_compare_compat_l :
-  forall n m p:Z, p > 0 -> (n ?= m) = (p * n ?= p * m).
-Proof.
-  intros x y z H; destruct z.
-  discriminate H.
-  rewrite Zcompare_mult_compat; reflexivity.
-  discriminate H.
-Qed.
-
-Lemma Zmult_compare_compat_r :
-  forall n m p:Z, p > 0 -> (n ?= m) = (n * p ?= m * p).
-Proof.
-  intros x y z H; rewrite (Zmult_comm x z); rewrite (Zmult_comm y z);
-    apply Zmult_compare_compat_l; assumption.
-Qed.
+Notation Zcompare_refl := Z.compare_refl (only parsing).
+Notation Zcompare_Eq_eq := Z.compare_eq (only parsing).
+Notation Zcompare_Eq_iff_eq := Z.compare_eq_iff (only parsing).
+Notation Zcompare_spec := Z.compare_spec (only parsing).
+Notation Zmin_l := Z.min_l (only parsing).
+Notation Zmin_r := Z.min_r (only parsing).
+Notation Zmax_l := Z.max_l (only parsing).
+Notation Zmax_r := Z.max_r (only parsing).
+Notation Zabs_eq := Z.abs_eq (only parsing).
+Notation Zabs_non_eq := Z.abs_neq (only parsing).
+Notation Zsgn_0 := Z.sgn_null (only parsing).
+Notation Zsgn_1 := Z.sgn_pos (only parsing).
+Notation Zsgn_m1 := Z.sgn_neg (only parsing).
 
+(** Not kept: Zcompare_egal_dec *)