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-rw-r--r--theories/ZArith/Zcompare.v78
1 files changed, 46 insertions, 32 deletions
diff --git a/theories/ZArith/Zcompare.v b/theories/ZArith/Zcompare.v
index 8244d4ce..3e611d54 100644
--- a/theories/ZArith/Zcompare.v
+++ b/theories/ZArith/Zcompare.v
@@ -1,3 +1,4 @@
+(* -*- coding: utf-8 -*- *)
(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
@@ -9,7 +10,7 @@
(*i $$ i*)
(**********************************************************************)
-(** Binary Integers (Pierre Crégut, CNET, Lannion, France) *)
+(** Binary Integers (Pierre Crégut, CNET, Lannion, France) *)
(**********************************************************************)
Require Export BinPos.
@@ -40,12 +41,12 @@ Proof.
| destruct ((x' ?= y')%positive Eq); reflexivity || discriminate ] ].
Qed.
-Ltac destr_zcompare :=
- match goal with |- context [Zcompare ?x ?y] =>
- let H := fresh "H" in
+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 |
change (x>y)%Z in H ]
end.
@@ -58,35 +59,48 @@ 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 || 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; split; intro H;
- [ change Lt with (CompOpp Gt) in |- *; rewrite <- Zcompare_antisym;
- rewrite H; reflexivity
- | change Gt with (CompOpp Lt) in |- *; rewrite <- Zcompare_antisym;
- rewrite H; reflexivity ].
+ 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.
+
+
(** * 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.
+
Lemma Zcompare_Gt_trans :
forall n m p:Z, (n ?= m) = Gt -> (m ?= p) = Gt -> (n ?= p) = Gt.
Proof.
- intros x y z; case x; case y; case z; simpl in |- *;
- try (intros; discriminate H || discriminate H0); auto with arith;
- [ intros p q r H H0; apply nat_of_P_gt_Gt_compare_complement_morphism;
- unfold gt in |- *; apply lt_trans with (m := nat_of_P q);
- apply nat_of_P_lt_Lt_compare_morphism; apply ZC1;
- assumption
- | intros p q r; do 3 rewrite <- ZC4; intros H H0;
- apply nat_of_P_gt_Gt_compare_complement_morphism;
- unfold gt in |- *; apply lt_trans with (m := nat_of_P q);
- apply nat_of_P_lt_Lt_compare_morphism; apply ZC1;
- assumption ].
+ 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.
Qed.
(** * Comparison and opposite *)
@@ -129,7 +143,7 @@ Proof.
[ reflexivity
| apply H
| rewrite (Zcompare_opp x y); rewrite Zcompare_opp;
- do 2 rewrite Zopp_plus_distr; rewrite Zopp_neg;
+ do 2 rewrite Zopp_plus_distr; rewrite Zopp_neg;
apply H ].
Qed.
@@ -145,7 +159,7 @@ Proof.
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;
+ 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
@@ -170,7 +184,7 @@ Proof.
[ 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;
+ 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);
@@ -273,7 +287,7 @@ Proof.
[ 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;
+ apply nat_of_P_lt_Lt_compare_morphism;
assumption
| apply lt_le_weak; apply nat_of_P_lt_Lt_compare_morphism;
apply ZC1; assumption ]
@@ -289,7 +303,7 @@ Proof.
[ 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 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 ]
@@ -330,7 +344,7 @@ Qed.
Lemma Zcompare_succ_Gt : forall n:Z, (Zsucc n ?= n) = Gt.
Proof.
intro x; unfold Zsucc in |- *; pattern x at 2 in |- *;
- rewrite <- (Zplus_0_r x); rewrite Zcompare_plus_compat;
+ rewrite <- (Zplus_0_r x); rewrite Zcompare_plus_compat;
reflexivity.
Qed.
@@ -351,7 +365,7 @@ Proof.
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_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);
@@ -369,7 +383,7 @@ Proof.
intros n m; unfold Zsucc in |- *; do 2 rewrite (fun t:Z => Zplus_comm t 1);
rewrite Zcompare_plus_compat; auto with arith.
Qed.
-
+
(** * Multiplication and comparison *)
Lemma Zcompare_mult_compat :
@@ -394,7 +408,7 @@ Qed.
Lemma rename :
forall (A:Type) (P:A -> Prop) (x:A), (forall y:A, x = y -> P y) -> P x.
Proof.
- auto with arith.
+ auto with arith.
Qed.
Lemma Zcompare_elim :
@@ -473,7 +487,7 @@ Lemma Zge_compare :
| Gt => True
end.
Proof.
- intros x y; unfold Zge in |- *; elim (x ?= y); auto with arith.
+ intros x y; unfold Zge in |- *; elim (x ?= y); auto with arith.
Qed.
Lemma Zgt_compare :
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 13:12:27 +0000