-
Notifications
You must be signed in to change notification settings - Fork 2
/
Copy pathCoqLib.v
1433 lines (1204 loc) · 39.2 KB
/
CoqLib.v
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
(* *********************************************************************)
(* *)
(* The Compcert verified compiler *)
(* *)
(* Xavier Leroy, INRIA Paris-Rocquencourt *)
(* *)
(* Copyright Institut National de Recherche en Informatique et en *)
(* Automatique. All rights reserved. This file is distributed *)
(* under the terms of the GNU General Public License as published by *)
(* the Free Software Foundation, either version 2 of the License, or *)
(* (at your option) any later version. This file is also distributed *)
(* under the terms of the INRIA Non-Commercial License Agreement. *)
(* *)
(* *********************************************************************)
(** This file collects a number of definitions and theorems that are
used throughout the development. It complements the Coq standard
library. *)
Require Export ZArith.
Require Export Znumtheory.
Require Export List.
Require Export Bool.
Global Set Asymmetric Patterns.
(** * Useful tactics *)
Ltac inv H := inversion H; clear H; subst.
Ltac predSpec pred predspec x y :=
generalize (predspec x y); case (pred x y); intro.
Ltac caseEq name :=
generalize (refl_equal name); pattern name at -1 in |- *; case name.
Ltac destructEq name :=
destruct name eqn:?.
Ltac decEq :=
match goal with
| [ |- _ = _ ] => f_equal
| [ |- (?X ?A <> ?X ?B) ] =>
cut (A <> B); [intro; congruence | try discriminate]
end.
Ltac byContradiction :=
cut False; [contradiction|idtac].
Ltac omegaContradiction :=
cut False; [contradiction|omega].
Lemma modusponens: forall (P Q: Prop), P -> (P -> Q) -> Q.
Proof. auto. Qed.
Ltac exploit x :=
refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _ _) _)
|| refine (modusponens _ _ (x _ _ _) _)
|| refine (modusponens _ _ (x _ _) _)
|| refine (modusponens _ _ (x _) _).
(** * Definitions and theorems over the type [positive] *)
Definition peq: forall (x y: positive), {x = y} + {x <> y} := Pos.eq_dec.
Global Opaque peq.
Lemma peq_true:
forall (A: Type) (x: positive) (a b: A), (if peq x x then a else b) = a.
Proof.
intros. case (peq x x); intros.
auto.
elim n; auto.
Qed.
Lemma peq_false:
forall (A: Type) (x y: positive) (a b: A), x <> y -> (if peq x y then a else b) = b.
Proof.
intros. case (peq x y); intros.
elim H; auto.
auto.
Qed.
Definition Plt: positive -> positive -> Prop := Pos.lt.
Lemma Plt_ne:
forall (x y: positive), Plt x y -> x <> y.
Proof.
unfold Plt; intros. red; intro. subst y. eelim Pos.lt_irrefl; eauto.
Qed.
Hint Resolve Plt_ne: coqlib.
Lemma Plt_trans:
forall (x y z: positive), Plt x y -> Plt y z -> Plt x z.
Proof (Pos.lt_trans).
Lemma Plt_succ:
forall (x: positive), Plt x (Psucc x).
Proof.
unfold Plt; intros. apply Pos.lt_succ_r. apply Pos.le_refl.
Qed.
Hint Resolve Plt_succ: coqlib.
Lemma Plt_trans_succ:
forall (x y: positive), Plt x y -> Plt x (Psucc y).
Proof.
intros. apply Plt_trans with y. assumption. apply Plt_succ.
Qed.
Hint Resolve Plt_succ: coqlib.
Lemma Plt_succ_inv:
forall (x y: positive), Plt x (Psucc y) -> Plt x y \/ x = y.
Proof.
unfold Plt; intros. rewrite Pos.lt_succ_r in H.
apply Pos.le_lteq; auto.
Qed.
Definition plt (x y: positive) : {Plt x y} + {~ Plt x y}.
Proof.
unfold Plt, Pos.lt; intros. destruct (Pos.compare x y).
- right; congruence.
- left; auto.
- right; congruence.
Defined.
Global Opaque plt.
Definition Ple: positive -> positive -> Prop := Pos.le.
Lemma Ple_refl: forall (p: positive), Ple p p.
Proof (Pos.le_refl).
Lemma Ple_trans: forall (p q r: positive), Ple p q -> Ple q r -> Ple p r.
Proof (Pos.le_trans).
Lemma Plt_Ple: forall (p q: positive), Plt p q -> Ple p q.
Proof (Pos.lt_le_incl).
Lemma Ple_succ: forall (p: positive), Ple p (Psucc p).
Proof.
intros. apply Plt_Ple. apply Plt_succ.
Qed.
Lemma Plt_Ple_trans:
forall (p q r: positive), Plt p q -> Ple q r -> Plt p r.
Proof (Pos.lt_le_trans).
Lemma Plt_strict: forall p, ~ Plt p p.
Proof (Pos.lt_irrefl).
Hint Resolve Ple_refl Plt_Ple Ple_succ Plt_strict: coqlib.
Ltac xomega := unfold Plt, Ple in *; zify; omega.
Ltac xomegaContradiction := exfalso; xomega.
(** Peano recursion over positive numbers. *)
Section POSITIVE_ITERATION.
Lemma Plt_wf: well_founded Plt.
Proof.
apply well_founded_lt_compat with nat_of_P.
intros. apply nat_of_P_lt_Lt_compare_morphism. exact H.
Qed.
Variable A: Type.
Variable v1: A.
Variable f: positive -> A -> A.
Lemma Ppred_Plt:
forall x, x <> xH -> Plt (Ppred x) x.
Proof.
intros. elim (Psucc_pred x); intro. contradiction.
set (y := Ppred x) in *. rewrite <- H0. apply Plt_succ.
Qed.
Let iter (x: positive) (P: forall y, Plt y x -> A) : A :=
match peq x xH with
| left EQ => v1
| right NOTEQ => f (Ppred x) (P (Ppred x) (Ppred_Plt x NOTEQ))
end.
Definition positive_rec : positive -> A :=
Fix Plt_wf (fun _ => A) iter.
Lemma unroll_positive_rec:
forall x,
positive_rec x = iter x (fun y _ => positive_rec y).
Proof.
unfold positive_rec. apply (Fix_eq Plt_wf (fun _ => A) iter).
intros. unfold iter. case (peq x 1); intro. auto. decEq. apply H.
Qed.
Lemma positive_rec_base:
positive_rec 1%positive = v1.
Proof.
rewrite unroll_positive_rec. unfold iter. case (peq 1 1); intro.
auto. elim n; auto.
Qed.
Lemma positive_rec_succ:
forall x, positive_rec (Psucc x) = f x (positive_rec x).
Proof.
intro. rewrite unroll_positive_rec. unfold iter.
case (peq (Psucc x) 1); intro.
destruct x; simpl in e; discriminate.
rewrite Ppred_succ. auto.
Qed.
Lemma positive_Peano_ind:
forall (P: positive -> Prop),
P xH ->
(forall x, P x -> P (Psucc x)) ->
forall x, P x.
Proof.
intros.
apply (well_founded_ind Plt_wf P).
intros.
case (peq x0 xH); intro.
subst x0; auto.
elim (Psucc_pred x0); intro. contradiction. rewrite <- H2.
apply H0. apply H1. apply Ppred_Plt. auto.
Qed.
End POSITIVE_ITERATION.
(** * Definitions and theorems over the type [Z] *)
Definition zeq: forall (x y: Z), {x = y} + {x <> y} := Z.eq_dec.
Lemma zeq_true:
forall (A: Type) (x: Z) (a b: A), (if zeq x x then a else b) = a.
Proof.
intros. case (zeq x x); intros.
auto.
elim n; auto.
Qed.
Lemma zeq_false:
forall (A: Type) (x y: Z) (a b: A), x <> y -> (if zeq x y then a else b) = b.
Proof.
intros. case (zeq x y); intros.
elim H; auto.
auto.
Qed.
Open Scope Z_scope.
Definition zlt: forall (x y: Z), {x < y} + {x >= y} := Z_lt_dec.
Lemma zlt_true:
forall (A: Type) (x y: Z) (a b: A),
x < y -> (if zlt x y then a else b) = a.
Proof.
intros. case (zlt x y); intros.
auto.
omegaContradiction.
Qed.
Lemma zlt_false:
forall (A: Type) (x y: Z) (a b: A),
x >= y -> (if zlt x y then a else b) = b.
Proof.
intros. case (zlt x y); intros.
omegaContradiction.
auto.
Qed.
Definition zle: forall (x y: Z), {x <= y} + {x > y} := Z_le_gt_dec.
Lemma zle_true:
forall (A: Type) (x y: Z) (a b: A),
x <= y -> (if zle x y then a else b) = a.
Proof.
intros. case (zle x y); intros.
auto.
omegaContradiction.
Qed.
Lemma zle_false:
forall (A: Type) (x y: Z) (a b: A),
x > y -> (if zle x y then a else b) = b.
Proof.
intros. case (zle x y); intros.
omegaContradiction.
auto.
Qed.
(** Properties of powers of two. *)
Lemma two_power_nat_O : two_power_nat O = 1.
Proof. reflexivity. Qed.
Lemma two_power_nat_pos : forall n : nat, two_power_nat n > 0.
Proof.
induction n. rewrite two_power_nat_O. omega.
rewrite two_power_nat_S. omega.
Qed.
Lemma two_power_nat_two_p:
forall x, two_power_nat x = two_p (Z_of_nat x).
Proof.
induction x. auto.
rewrite two_power_nat_S. rewrite inj_S. rewrite two_p_S. omega. omega.
Qed.
Lemma two_p_monotone:
forall x y, 0 <= x <= y -> two_p x <= two_p y.
Proof.
intros.
replace (two_p x) with (two_p x * 1) by omega.
replace y with (x + (y - x)) by omega.
rewrite two_p_is_exp; try omega.
apply Zmult_le_compat_l.
assert (two_p (y - x) > 0). apply two_p_gt_ZERO. omega. omega.
assert (two_p x > 0). apply two_p_gt_ZERO. omega. omega.
Qed.
Lemma two_p_monotone_strict:
forall x y, 0 <= x < y -> two_p x < two_p y.
Proof.
intros. assert (two_p x <= two_p (y - 1)). apply two_p_monotone; omega.
assert (two_p (y - 1) > 0). apply two_p_gt_ZERO. omega.
replace y with (Zsucc (y - 1)) by omega. rewrite two_p_S. omega. omega.
Qed.
Lemma two_p_strict:
forall x, x >= 0 -> x < two_p x.
Proof.
intros x0 GT. pattern x0. apply natlike_ind.
simpl. omega.
intros. rewrite two_p_S; auto. generalize (two_p_gt_ZERO x H). omega.
omega.
Qed.
Lemma two_p_strict_2:
forall x, x >= 0 -> 2 * x - 1 < two_p x.
Proof.
intros. assert (x = 0 \/ x - 1 >= 0) by omega. destruct H0.
subst. vm_compute. auto.
replace (two_p x) with (2 * two_p (x - 1)).
generalize (two_p_strict _ H0). omega.
rewrite <- two_p_S. decEq. omega. omega.
Qed.
(** Properties of [Zmin] and [Zmax] *)
Lemma Zmin_spec:
forall x y, Zmin x y = if zlt x y then x else y.
Proof.
intros. case (zlt x y); unfold Zlt, Zge; intro z.
unfold Zmin. rewrite z. auto.
unfold Zmin. caseEq (x ?= y); intro.
apply Zcompare_Eq_eq. auto.
contradiction.
reflexivity.
Qed.
Lemma Zmax_spec:
forall x y, Zmax x y = if zlt y x then x else y.
Proof.
intros. case (zlt y x); unfold Zlt, Zge; intro z.
unfold Zmax. rewrite <- (Zcompare_antisym y x).
rewrite z. simpl. auto.
unfold Zmax. rewrite <- (Zcompare_antisym y x).
caseEq (y ?= x); intro; simpl.
symmetry. apply Zcompare_Eq_eq. auto.
contradiction. reflexivity.
Qed.
Lemma Zmax_bound_l:
forall x y z, x <= y -> x <= Zmax y z.
Proof.
intros. generalize (Zmax1 y z). omega.
Qed.
Lemma Zmax_bound_r:
forall x y z, x <= z -> x <= Zmax y z.
Proof.
intros. generalize (Zmax2 y z). omega.
Qed.
(** Properties of Euclidean division and modulus. *)
Lemma Zdiv_small:
forall x y, 0 <= x < y -> x / y = 0.
Proof.
intros. assert (y > 0). omega.
assert (forall a b,
0 <= a < y ->
0 <= y * b + a < y ->
b = 0).
intros.
assert (b = 0 \/ b > 0 \/ (-b) > 0). omega.
elim H3; intro.
auto.
elim H4; intro.
assert (y * b >= y * 1). apply Zmult_ge_compat_l. omega. omega.
omegaContradiction.
assert (y * (-b) >= y * 1). apply Zmult_ge_compat_l. omega. omega.
rewrite <- Zopp_mult_distr_r in H6. omegaContradiction.
apply H1 with (x mod y).
apply Z_mod_lt. auto.
rewrite <- Z_div_mod_eq. auto. auto.
Qed.
Lemma Zmod_small:
forall x y, 0 <= x < y -> x mod y = x.
Proof.
intros. assert (y > 0). omega.
generalize (Z_div_mod_eq x y H0).
rewrite (Zdiv_small x y H). omega.
Qed.
Lemma Zmod_unique:
forall x y a b,
x = a * y + b -> 0 <= b < y -> x mod y = b.
Proof.
intros. subst x. rewrite Zplus_comm.
rewrite Z_mod_plus. apply Zmod_small. auto. omega.
Qed.
Lemma Zdiv_unique:
forall x y a b,
x = a * y + b -> 0 <= b < y -> x / y = a.
Proof.
intros. subst x. rewrite Zplus_comm.
rewrite Z_div_plus. rewrite (Zdiv_small b y H0). omega. omega.
Qed.
Lemma Zdiv_Zdiv:
forall a b c,
b > 0 -> c > 0 -> (a / b) / c = a / (b * c).
Proof.
intros.
generalize (Z_div_mod_eq a b H). generalize (Z_mod_lt a b H). intros.
generalize (Z_div_mod_eq (a/b) c H0). generalize (Z_mod_lt (a/b) c H0). intros.
set (q1 := a / b) in *. set (r1 := a mod b) in *.
set (q2 := q1 / c) in *. set (r2 := q1 mod c) in *.
symmetry. apply Zdiv_unique with (r2 * b + r1).
rewrite H2. rewrite H4. ring.
split.
assert (0 <= r2 * b). apply Zmult_le_0_compat. omega. omega. omega.
assert ((r2 + 1) * b <= c * b).
apply Zmult_le_compat_r. omega. omega.
replace ((r2 + 1) * b) with (r2 * b + b) in H5 by ring.
replace (c * b) with (b * c) in H5 by ring.
omega.
Qed.
Lemma Zmult_le_compat_l_neg :
forall n m p:Z, n >= m -> p <= 0 -> p * n <= p * m.
Proof.
intros.
assert ((-p) * n >= (-p) * m). apply Zmult_ge_compat_l. auto. omega.
replace (p * n) with (- ((-p) * n)) by ring.
replace (p * m) with (- ((-p) * m)) by ring.
omega.
Qed.
Lemma Zdiv_interval_1:
forall lo hi a b,
lo <= 0 -> hi > 0 -> b > 0 ->
lo * b <= a < hi * b ->
lo <= a/b < hi.
Proof.
intros.
generalize (Z_div_mod_eq a b H1). generalize (Z_mod_lt a b H1). intros.
set (q := a/b) in *. set (r := a mod b) in *.
split.
assert (lo < (q + 1)).
apply Zmult_lt_reg_r with b. omega.
apply Zle_lt_trans with a. omega.
replace ((q + 1) * b) with (b * q + b) by ring.
omega.
omega.
apply Zmult_lt_reg_r with b. omega.
replace (q * b) with (b * q) by ring.
omega.
Qed.
Lemma Zdiv_interval_2:
forall lo hi a b,
lo <= a <= hi -> lo <= 0 -> hi >= 0 -> b > 0 ->
lo <= a/b <= hi.
Proof.
intros.
assert (lo <= a / b < hi+1).
apply Zdiv_interval_1. omega. omega. auto.
assert (lo * b <= lo * 1). apply Zmult_le_compat_l_neg. omega. omega.
replace (lo * 1) with lo in H3 by ring.
assert ((hi + 1) * 1 <= (hi + 1) * b). apply Zmult_le_compat_l. omega. omega.
replace ((hi + 1) * 1) with (hi + 1) in H4 by ring.
omega.
omega.
Qed.
Lemma Zmod_recombine:
forall x a b,
a > 0 -> b > 0 ->
x mod (a * b) = ((x/b) mod a) * b + (x mod b).
Proof.
intros.
set (xb := x/b).
apply Zmod_unique with (xb/a).
generalize (Z_div_mod_eq x b H0); fold xb; intro EQ1.
generalize (Z_div_mod_eq xb a H); intro EQ2.
rewrite EQ2 in EQ1.
eapply trans_eq. eexact EQ1. ring.
generalize (Z_mod_lt x b H0). intro.
generalize (Z_mod_lt xb a H). intro.
assert (0 <= xb mod a * b <= a * b - b).
split. apply Zmult_le_0_compat; omega.
replace (a * b - b) with ((a - 1) * b) by ring.
apply Zmult_le_compat; omega.
omega.
Qed.
(** Properties of divisibility. *)
Lemma Zdivides_trans:
forall x y z, (x | y) -> (y | z) -> (x | z).
Proof.
intros x y z [a A] [b B]; subst. exists (a*b); ring.
Qed.
Definition Zdivide_dec:
forall (p q: Z), p > 0 -> { (p|q) } + { ~(p|q) }.
Proof.
intros. destruct (zeq (Zmod q p) 0).
left. exists (q / p).
transitivity (p * (q / p) + (q mod p)). apply Z_div_mod_eq; auto.
transitivity (p * (q / p)). omega. ring.
right; red; intros. elim n. apply Z_div_exact_1; auto.
inv H0. rewrite Z_div_mult; auto. ring.
Defined.
Global Opaque Zdivide_dec.
Lemma Zdivide_interval:
forall a b c,
0 < c -> 0 <= a < b -> (c | a) -> (c | b) -> 0 <= a <= b - c.
Proof.
intros. destruct H1 as [x EQ1]. destruct H2 as [y EQ2]. subst. destruct H0.
split. omega. exploit Zmult_lt_reg_r; eauto. intros.
replace (y * c - c) with ((y - 1) * c) by ring.
apply Zmult_le_compat_r; omega.
Qed.
(** Conversion from [Z] to [nat]. *)
Definition nat_of_Z: Z -> nat := Z.to_nat.
Lemma nat_of_Z_of_nat:
forall n, nat_of_Z (Z_of_nat n) = n.
Proof.
exact Nat2Z.id.
Qed.
Lemma nat_of_Z_max:
forall z, Z_of_nat (nat_of_Z z) = Zmax z 0.
Proof.
intros. unfold Zmax. destruct z; simpl; auto.
change (Z.of_nat (Z.to_nat (Zpos p)) = Zpos p).
apply Z2Nat.id. compute; intuition congruence.
Qed.
Lemma nat_of_Z_eq:
forall z, z >= 0 -> Z_of_nat (nat_of_Z z) = z.
Proof.
unfold nat_of_Z; intros. apply Z2Nat.id. omega.
Qed.
Lemma nat_of_Z_neg:
forall n, n <= 0 -> nat_of_Z n = O.
Proof.
destruct n; unfold Zle; simpl; auto. congruence.
Qed.
Lemma nat_of_Z_plus:
forall p q,
p >= 0 -> q >= 0 ->
nat_of_Z (p + q) = (nat_of_Z p + nat_of_Z q)%nat.
Proof.
unfold nat_of_Z; intros. apply Z2Nat.inj_add; omega.
Qed.
(** Alignment: [align n amount] returns the smallest multiple of [amount]
greater than or equal to [n]. *)
Definition align (n: Z) (amount: Z) :=
((n + amount - 1) / amount) * amount.
Lemma align_le: forall x y, y > 0 -> x <= align x y.
Proof.
intros. unfold align.
generalize (Z_div_mod_eq (x + y - 1) y H). intro.
replace ((x + y - 1) / y * y)
with ((x + y - 1) - (x + y - 1) mod y).
generalize (Z_mod_lt (x + y - 1) y H). omega.
rewrite Zmult_comm. omega.
Qed.
Lemma align_divides: forall x y, y > 0 -> (y | align x y).
Proof.
intros. unfold align. apply Zdivide_factor_l.
Qed.
(** * Definitions and theorems on the data types [option], [sum] and [list] *)
Set Implicit Arguments.
(** Comparing option types. *)
Definition option_eq (A: Type) (eqA: forall (x y: A), {x=y} + {x<>y}):
forall (x y: option A), {x=y} + {x<>y}.
Proof. decide equality. Defined.
Global Opaque option_eq.
(** Lifting a relation to an option type. *)
Inductive option_rel (A B: Type) (R: A -> B -> Prop) : option A -> option B -> Prop :=
| option_rel_none: option_rel R None None
| option_rel_some: forall x y, R x y -> option_rel R (Some x) (Some y).
(** Mapping a function over an option type. *)
Definition option_map (A B: Type) (f: A -> B) (x: option A) : option B :=
match x with
| None => None
| Some y => Some (f y)
end.
(** Mapping a function over a sum type. *)
Definition sum_left_map (A B C: Type) (f: A -> B) (x: A + C) : B + C :=
match x with
| inl y => inl C (f y)
| inr z => inr B z
end.
(** Properties of [List.nth] (n-th element of a list). *)
Hint Resolve in_eq in_cons: coqlib.
Lemma nth_error_in:
forall (A: Type) (n: nat) (l: list A) (x: A),
List.nth_error l n = Some x -> In x l.
Proof.
induction n; simpl.
destruct l; intros.
discriminate.
injection H; intro; subst a. apply in_eq.
destruct l; intros.
discriminate.
apply in_cons. auto.
Qed.
Hint Resolve nth_error_in: coqlib.
Lemma nth_error_nil:
forall (A: Type) (idx: nat), nth_error (@nil A) idx = None.
Proof.
induction idx; simpl; intros; reflexivity.
Qed.
Hint Resolve nth_error_nil: coqlib.
(** Compute the length of a list, with result in [Z]. *)
Fixpoint list_length_z_aux (A: Type) (l: list A) (acc: Z) {struct l}: Z :=
match l with
| nil => acc
| hd :: tl => list_length_z_aux tl (Zsucc acc)
end.
Remark list_length_z_aux_shift:
forall (A: Type) (l: list A) n m,
list_length_z_aux l n = list_length_z_aux l m + (n - m).
Proof.
induction l; intros; simpl.
omega.
replace (n - m) with (Zsucc n - Zsucc m) by omega. auto.
Qed.
Definition list_length_z (A: Type) (l: list A) : Z :=
list_length_z_aux l 0.
Lemma list_length_z_cons:
forall (A: Type) (hd: A) (tl: list A),
list_length_z (hd :: tl) = list_length_z tl + 1.
Proof.
intros. unfold list_length_z. simpl.
rewrite (list_length_z_aux_shift tl 1 0). omega.
Qed.
Lemma list_length_z_pos:
forall (A: Type) (l: list A),
list_length_z l >= 0.
Proof.
induction l; simpl. unfold list_length_z; simpl. omega.
rewrite list_length_z_cons. omega.
Qed.
Lemma list_length_z_map:
forall (A B: Type) (f: A -> B) (l: list A),
list_length_z (map f l) = list_length_z l.
Proof.
induction l. reflexivity. simpl. repeat rewrite list_length_z_cons. congruence.
Qed.
(** Extract the n-th element of a list, as [List.nth_error] does,
but the index [n] is of type [Z]. *)
Fixpoint list_nth_z (A: Type) (l: list A) (n: Z) {struct l}: option A :=
match l with
| nil => None
| hd :: tl => if zeq n 0 then Some hd else list_nth_z tl (Zpred n)
end.
Lemma list_nth_z_in:
forall (A: Type) (l: list A) n x,
list_nth_z l n = Some x -> In x l.
Proof.
induction l; simpl; intros.
congruence.
destruct (zeq n 0). left; congruence. right; eauto.
Qed.
Lemma list_nth_z_map:
forall (A B: Type) (f: A -> B) (l: list A) n,
list_nth_z (List.map f l) n = option_map f (list_nth_z l n).
Proof.
induction l; simpl; intros.
auto.
destruct (zeq n 0). auto. eauto.
Qed.
Lemma list_nth_z_range:
forall (A: Type) (l: list A) n x,
list_nth_z l n = Some x -> 0 <= n < list_length_z l.
Proof.
induction l; simpl; intros.
discriminate.
rewrite list_length_z_cons. destruct (zeq n 0).
generalize (list_length_z_pos l); omega.
exploit IHl; eauto. omega.
Qed.
(** Properties of [List.incl] (list inclusion). *)
Lemma incl_cons_inv:
forall (A: Type) (a: A) (b c: list A),
incl (a :: b) c -> incl b c.
Proof.
unfold incl; intros. apply H. apply in_cons. auto.
Qed.
Hint Resolve incl_cons_inv: coqlib.
Lemma incl_app_inv_l:
forall (A: Type) (l1 l2 m: list A),
incl (l1 ++ l2) m -> incl l1 m.
Proof.
unfold incl; intros. apply H. apply in_or_app. left; assumption.
Qed.
Lemma incl_app_inv_r:
forall (A: Type) (l1 l2 m: list A),
incl (l1 ++ l2) m -> incl l2 m.
Proof.
unfold incl; intros. apply H. apply in_or_app. right; assumption.
Qed.
Hint Resolve incl_tl incl_refl incl_app_inv_l incl_app_inv_r: coqlib.
Lemma incl_same_head:
forall (A: Type) (x: A) (l1 l2: list A),
incl l1 l2 -> incl (x::l1) (x::l2).
Proof.
intros; red; simpl; intros. intuition.
Qed.
(** Properties of [List.map] (mapping a function over a list). *)
Lemma list_map_exten:
forall (A B: Type) (f f': A -> B) (l: list A),
(forall x, In x l -> f x = f' x) ->
List.map f' l = List.map f l.
Proof.
induction l; simpl; intros.
reflexivity.
rewrite <- H. rewrite IHl. reflexivity.
intros. apply H. tauto.
tauto.
Qed.
Lemma list_map_compose:
forall (A B C: Type) (f: A -> B) (g: B -> C) (l: list A),
List.map g (List.map f l) = List.map (fun x => g(f x)) l.
Proof.
induction l; simpl. reflexivity. rewrite IHl; reflexivity.
Qed.
Lemma list_map_identity:
forall (A: Type) (l: list A),
List.map (fun (x:A) => x) l = l.
Proof.
induction l; simpl; congruence.
Qed.
Lemma list_map_nth:
forall (A B: Type) (f: A -> B) (l: list A) (n: nat),
nth_error (List.map f l) n = option_map f (nth_error l n).
Proof.
induction l; simpl; intros.
repeat rewrite nth_error_nil. reflexivity.
destruct n; simpl. reflexivity. auto.
Qed.
Lemma list_length_map:
forall (A B: Type) (f: A -> B) (l: list A),
List.length (List.map f l) = List.length l.
Proof.
induction l; simpl; congruence.
Qed.
Lemma list_in_map_inv:
forall (A B: Type) (f: A -> B) (l: list A) (y: B),
In y (List.map f l) -> exists x:A, y = f x /\ In x l.
Proof.
induction l; simpl; intros.
contradiction.
elim H; intro.
exists a; intuition auto.
generalize (IHl y H0). intros [x [EQ IN]].
exists x; tauto.
Qed.
Lemma list_append_map:
forall (A B: Type) (f: A -> B) (l1 l2: list A),
List.map f (l1 ++ l2) = List.map f l1 ++ List.map f l2.
Proof.
induction l1; simpl; intros.
auto. rewrite IHl1. auto.
Qed.
Lemma list_append_map_inv:
forall (A B: Type) (f: A -> B) (m1 m2: list B) (l: list A),
List.map f l = m1 ++ m2 ->
exists l1, exists l2, List.map f l1 = m1 /\ List.map f l2 = m2 /\ l = l1 ++ l2.
Proof.
induction m1; simpl; intros.
exists (@nil A); exists l; auto.
destruct l; simpl in H; inv H.
exploit IHm1; eauto. intros [l1 [l2 [P [Q R]]]]. subst l.
exists (a0 :: l1); exists l2; intuition. simpl; congruence.
Qed.
(** Folding a function over a list *)
Section LIST_FOLD.
Variables A B: Type.
Variable f: A -> B -> B.
(** This is exactly [List.fold_left] from Coq's standard library,
with [f] taking arguments in a different order. *)
Fixpoint list_fold_left (accu: B) (l: list A) : B :=
match l with nil => accu | x :: l' => list_fold_left (f x accu) l' end.
(** This is exactly [List.fold_right] from Coq's standard library,
except that it runs in constant stack space. *)
Definition list_fold_right (l: list A) (base: B) : B :=
list_fold_left base (List.rev' l).
Remark list_fold_left_app:
forall l1 l2 accu,
list_fold_left accu (l1 ++ l2) = list_fold_left (list_fold_left accu l1) l2.
Proof.
induction l1; simpl; intros.
auto.
rewrite IHl1. auto.
Qed.
Lemma list_fold_right_eq:
forall l base,
list_fold_right l base =
match l with nil => base | x :: l' => f x (list_fold_right l' base) end.
Proof.
unfold list_fold_right; intros.
destruct l.
auto.
unfold rev'. rewrite <- ! rev_alt. simpl.
rewrite list_fold_left_app. simpl. auto.
Qed.
Lemma list_fold_right_spec:
forall l base, list_fold_right l base = List.fold_right f base l.
Proof.
induction l; simpl; intros; rewrite list_fold_right_eq; congruence.
Qed.
End LIST_FOLD.
(** Properties of list membership. *)
Lemma in_cns:
forall (A: Type) (x y: A) (l: list A), In x (y :: l) <-> y = x \/ In x l.
Proof.
intros. simpl. tauto.
Qed.
Lemma in_app:
forall (A: Type) (x: A) (l1 l2: list A), In x (l1 ++ l2) <-> In x l1 \/ In x l2.
Proof.
intros. split; intro. apply in_app_or. auto. apply in_or_app. auto.
Qed.
Lemma list_in_insert:
forall (A: Type) (x: A) (l1 l2: list A) (y: A),
In x (l1 ++ l2) -> In x (l1 ++ y :: l2).
Proof.
intros. apply in_or_app; simpl. elim (in_app_or _ _ _ H); intro; auto.
Qed.
(** [list_disjoint l1 l2] holds iff [l1] and [l2] have no elements
in common. *)
Definition list_disjoint (A: Type) (l1 l2: list A) : Prop :=
forall (x y: A), In x l1 -> In y l2 -> x <> y.
Lemma list_disjoint_cons_l:
forall (A: Type) (a: A) (l1 l2: list A),
list_disjoint l1 l2 -> ~In a l2 -> list_disjoint (a :: l1) l2.
Proof.
unfold list_disjoint; simpl; intros. destruct H1. congruence. apply H; auto.
Qed.
Lemma list_disjoint_cons_r:
forall (A: Type) (a: A) (l1 l2: list A),
list_disjoint l1 l2 -> ~In a l1 -> list_disjoint l1 (a :: l2).
Proof.
unfold list_disjoint; simpl; intros. destruct H2. congruence. apply H; auto.
Qed.
Lemma list_disjoint_cons_left:
forall (A: Type) (a: A) (l1 l2: list A),
list_disjoint (a :: l1) l2 -> list_disjoint l1 l2.
Proof.
unfold list_disjoint; simpl; intros. apply H; tauto.
Qed.
Lemma list_disjoint_cons_right:
forall (A: Type) (a: A) (l1 l2: list A),
list_disjoint l1 (a :: l2) -> list_disjoint l1 l2.
Proof.
unfold list_disjoint; simpl; intros. apply H; tauto.
Qed.
Lemma list_disjoint_notin:
forall (A: Type) (l1 l2: list A) (a: A),
list_disjoint l1 l2 -> In a l1 -> ~(In a l2).
Proof.
unfold list_disjoint; intros; red; intros.
apply H with a a; auto.
Qed.
Lemma list_disjoint_sym:
forall (A: Type) (l1 l2: list A),
list_disjoint l1 l2 -> list_disjoint l2 l1.
Proof.
unfold list_disjoint; intros.