-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathLogic.html
1083 lines (835 loc) · 77.2 KB
/
Logic.html
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
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<link href="coqdoc.css" rel="stylesheet" type="text/css"/>
<title>Logic</title>
<script type="text/javascript" src="jquery-1.8.3.js"></script>
<script type="text/javascript" src="main.js"></script>
</head>
<body>
<div id="page">
<div id="header">
</div>
<div id="main">
<h1 class="libtitle">Logic</h1>
<div class="code code-tight">
</div>
<div class="doc">
<a name="lab191"></a><h1 class="section">Logic嚗oq銝剔��餉�蝟餌�</h1>
</div>
<div class="code code-space">
<br/>
<span class="id" type="keyword">Require</span> <span class="id" type="keyword">Export</span> <span class="id" type="var">BasicTactics</span>.<br/>
<br/>
</div>
<div class="doc">
Coq�蔭�餉�蝟餌����啣�嚗����箸���芣�<span class="inlinecode"><span class="id" type="keyword">Inductive</span></span>
摰�嚗蝘圈���<span class="inlinecode"><span style="font-family: arial;">∀</span></span>嚗誑��恬�<span class="inlinecode"><span style="font-family: arial;">→</span></span>嚗�蝘����隞虜閫��餉�餈
蝚色����摰��券�����貊�嚗�賢��刻�銝葵�箸��銵函內��
餈�蝡�閫��餈�銵函內�寞�撟嗅�蝷箏�雿蝙�其���隞祆閫血�����交敺撖孵��
餈�餈霂��賡��餉��函���撘�
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab192"></a><h1 class="section">�賡�</h1>
<div class="paragraph"> </div>
�其���蝡�銝剜�隞砍歇蝏��啗捂憭笆鈭�鈭�摰��膩嚗�<i>�賡�<i>嚗誑���箄�摰�
摰賑��摰抒�霂�瘜�<i>霂�<i>嚗��寡秩嚗�蛹甇Ｘ�隞砍歇蝏�銵�霈詨��賡���
霂�嚗�憒秩敶Ｗ�<span class="inlinecode"><span class="id" type="var">e1</span></span> <span class="inlinecode">=</span> <span class="inlinecode"><span class="id" type="var">e2</span></span>��<i>�貊��批憸�<i>嚗�怠�嚗�<span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">→</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>嚗�隞亙�����
憸�<span class="inlinecode"><span style="font-family: arial;">∀</span></span> <span class="inlinecode"><span class="id" type="var">x</span>,</span> <span class="inlinecode"><span class="id" type="var">P�</span>�<span class="id" type="var">�</span>�<span class="id" type="var">�</span>�<span class="id" type="var">�</span>�<span class="id" type="var">�</span>�</span>
<span class="inlinecode"></span>
<div class="paragraph"> </div>
�每oq銝哨�����刻◤霂���賜�鈭�掩�<span class="inlinecode"><span class="id" type="keyword">Prop</span></span>��
<div class="paragraph"> </div>
銝�臭�銝芸隞亥◤霂��憸�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Check</span> (3 = 3).<br/>
<span class="comment">(* ===> Prop *)</span><br/>
<br/>
</div>
<div class="doc">
銝�臭�銝芣�瘜◤霂��憸�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Check</span> (<span style="font-family: arial;">∀</span>(<span class="id" type="var">n</span>:<span class="id" type="var">nat</span>), <span class="id" type="var">n</span> = 2).<br/>
<span class="comment">(* ===> Prop *)</span><br/>
<br/>
</div>
<div class="doc">
�銝銝�<span class="inlinecode"><span class="id" type="keyword">Check</span></span>�賢�霈咀oq�曄內�葵銵刻噢撘�蝐餃���
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab193"></a><h1 class="section">霂�銝���</h1>
<div class="paragraph"> </div>
�每oq銝哨��賡�銝�<span class="inlinecode"><span class="id" type="var">nat</span></span>銋掩�掩�����雿停��嗆<span class="inlinecode">0</span>嚗�
<span class="inlinecode">1</span>嚗�<span class="inlinecode">2</span>��<span class="inlinecode"><span class="id" type="var">nat</span></span>��蝝��瘀�銝銝杭oq�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>����<i>霂�<i>雿蛹摰�����
�賑蝘啗�鈭�蝝蛹�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>��摰抒�<i>霂�憿�<i>proof term嚗�/
<i>霂�撖寡情<i>proof object嚗�/<i>霂<i>evidence嚗�
�每oq銝哨�敶�隞砍ㄟ�僎銝���餈�����嗅�
<div class="paragraph"> </div>
<div class="code code-tight">
<span class="id" type="keyword">Lemma</span> <span class="id" type="var">silly</span> : 0 � 3 = 0.<br/>
<span class="id" type="keyword">Proof</span>. <span class="id" type="tactic">reflexivity</span>. <span class="id" type="keyword">Qed</span>.
<div class="paragraph"> </div>
</div>
�賑��<span class="inlinecode"><span class="id" type="keyword">Proof</span></span>��<span class="inlinecode"><span class="id" type="keyword">Qed</span></span>�喲摮葉雿輻�����乩���Coq憒��銝銝芯�
銝箄�銝芸憸������★�餈葵蝷箄�銝哨��賡�<span class="inlinecode">0</span> <span class="inlinecode">�</span> <span class="inlinecode">3</span> <span class="inlinecode">=</span> <span class="inlinecode">0</span>鋡怎<span class="inlinecode"><span class="id" type="var">mult</span></span>��
銋�摰ㄟ��<span class="inlinecode">0</span> <span class="inlinecode">�</span> <span class="inlinecode">3</span>�賢�鋡怎��<span class="inlinecode">3</span>嚗��貊���<i>�芸���<i>摰ㄟ��<span class="inlinecode">0</span> <span class="inlinecode">=</span> <span class="inlinecode">0</span>嚗�
��������
<div class="paragraph"> </div>
<a name="lab194"></a><h3 class="section"> </h3>
</div>
<div class="code code-space">
<br/>
<span class="id" type="keyword">Lemma</span> <span class="id" type="var">silly</span> : 0 � 3 = 0.<br/>
<span class="id" type="keyword">Proof</span>. <span class="id" type="tactic">reflexivity</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
�賑�臭誑��<span class="inlinecode"><span class="id" type="keyword">Print</span></span>�誘�交�oq蝏�銝�賡���霂�憿對�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Print</span> <span class="id" type="var">silly</span>.<br/>
<span class="comment">(* ===> silly = eq_refl : 0 * 3 = 0 *)</span><br/>
<br/>
</div>
<div class="doc">
�刻���霂�憿�<span class="inlinecode"><span class="id" type="var">eq_refl</span></span>霂�鈭��蝑扼��賑隡撠��游���
�喃��貊��抒��捆��
<div class="paragraph"> </div>
<a name="lab195"></a><h2 class="section">�游<i>��<i>�賣</h2>
<div class="paragraph"> </div>
撠勗��賑�賢�隞亙�啁�敶Ｗ�摰�芰�唬�瘜��瘀�
<span class="inlinecode"></span>
<span class="inlinecode"><span class="id" type="var">mult</span></span> <span class="inlinecode">:</span> <span class="inlinecode"><span class="id" type="var">nat</span></span> <span class="inlinecode"><span style="font-family: arial;">→</span></span> <span class="inlinecode"><span class="id" type="var">nat</span></span> <span class="inlinecode"><span style="font-family: arial;">→</span></span> <span class="inlinecode"><span class="id" type="var">nat</span></span>
<span class="inlinecode"></span>
銝銝芾�怠�<span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">→</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>���★�臭�銝�<i>�賣<i>嚗�銝芸�唬誑�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>���桐�銝箄��伐�撟嗡�
��銝銝�<span class="inlinecode"><span class="id" type="var">Q</span></span>���桐�銝箏颲��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Lemma</span> <span class="id" type="var">silly_implication</span> : (1 + 1) = 2 <span style="font-family: arial;">→</span> 0 � 3 = 0.<br/>
<span class="id" type="keyword">Proof</span>. <span class="id" type="tactic">intros</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">reflexivity</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
�賑�賢��銝����霂�憿寧＆摰銝銝芸�堆�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Print</span> <span class="id" type="var">silly_implication</span>.<br/>
<span class="comment">(* ===> silly_implication = fun _ : 1 + 1 = 2 => eq_refl<br/>
: 1 + 1 = 2 -> 0 * 3 = 0 *)</span><br/>
<br/>
</div>
<div class="doc">
<a name="lab196"></a><h2 class="section">摰��賡�</h2>
<div class="paragraph"> </div>
撠勗��賑�賢��遣�芸�銋�敶熙�抒掩��瘥�霂游�銵典�鈭��嗉”蝷箇�
�芰�啗�鈭�隞砌���亥圻餈�蝐餃�嚗��瘀��賑銋憭�撱�<i>�芸�銋�<i>�賡���
�桅�嚗�憒�摰��葵�賡���銋�
<div class="paragraph"> </div>
<a name="lab197"></a><h3 class="section"> </h3>
<div class="paragraph"> </div>
�賡���銋霂湔�鈭�雿��嗡�霂�霂��賡�銝箇���<i>霂<i>��
<i>閫�<i>��<i>摰�<i>蝏��
<div class="paragraph"> </div>
<ul class="doclist">
<li> 銝�祈�嚗停�隞�桃掩���瘀�閫��航◤敶熙�批摰���
<div class="paragraph"> </div>
</li>
<li> �銝銝芸憸��冽瓷����桃��銝◤摰�妍銝箇���鈭憸◤蝘唬�
<i>�祉�<i>��
</li>
</ul>
�刻�銝蝡誑�銝���葉嚗�隞砍�隡��唳憭��餈�霂�憿孵�雿漣����蝏���
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab198"></a><h1 class="section">��嚗餉�"銝�"嚗�</h1>
<div class="paragraph"> </div>
�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>��<span class="inlinecode"><span class="id" type="var">Q</span></span>�餉����賢��典��思�銝芣�����<span class="inlinecode"><span class="id" type="keyword">Inductive</span></span>摰�銵函內��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Inductive</span> <span class="id" type="var">and</span> (<span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>) : <span class="id" type="keyword">Prop</span> :=<br/>
<span class="id" type="var">conj</span> : <span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> (<span class="id" type="var">and</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span>).<br/>
<br/>
</div>
<div class="doc">
�刻�銝芸�銋����渲����湔嚗蛹鈭���<span class="inlinecode"><span class="id" type="var">and</span></span> <span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>���殷��賑�閬�靘�
P���桀�Q���柴銝箇移蝖桃�霂湛�
<div class="paragraph"> </div>
<ul class="doclist">
<li> 憒�<span class="inlinecode"><span class="id" type="var">p</span></span>��<span class="inlinecode"><span class="id" type="var">P</span></span>���桐�<span class="inlinecode"><span class="id" type="var">q</span></span>��<span class="inlinecode"><span class="id" type="var">Q</span></span>���殷����<span class="inlinecode"><span class="id" type="var">conj</span></span> <span class="inlinecode"><span class="id" type="var">p</span></span> <span class="inlinecode"><span class="id" type="var">q</span></span>�臭誑鋡思�銝�<span class="inlinecode"><span class="id" type="var">and</span></span> <span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>���殷�
</li>
<li> ��餈���<i>�臭�<i>蝏<span class="inlinecode"><span class="id" type="var">and</span></span> <span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>���桃��寞����單霂湛�憒�靚��箔�銝銝�<span class="inlinecode"><span class="id" type="var">and</span></span> <span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>
���殷�����賑撠梯憭��亥�銝芾��桐�摰隞�<span class="inlinecode"><span class="id" type="var">conj</span></span> <span class="inlinecode"><span class="id" type="var">p</span></span> <span class="inlinecode"><span class="id" type="var">q</span></span>餈�敶Ｗ��箇���嗡葉<span class="inlinecode"><span class="id" type="var">p</span></span>��
<span class="inlinecode"><span class="id" type="var">P</span></span>���殷�<span class="inlinecode"><span class="id" type="var">q</span></span>��<span class="inlinecode"><span class="id" type="var">Q</span></span>���柴�
</li>
</ul>
<div class="paragraph"> </div>
�蛹�賑隡�撣訾蝙�典����隞亥悟�賑�亦�摰挽摰�銝芰���銝剔�銵函內蝚佗�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Notation</span> "P <span style="font-family: arial;">∧</span> Q" := (<span class="id" type="var">and</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span>) : <span class="id" type="var">type_scope</span>.<br/>
<br/>
</div>
<div class="doc">
嚗�<span class="inlinecode"><span class="id" type="var">type_scope</span></span>餈��扇��Coq蝟餌�餈葵蝚血撠��箇�典憸葉���臬�潔葉��
<div class="paragraph"> </div>
�斗��<span class="inlinecode"><span class="id" type="var">conj</span></span>��"蝐餃�"嚗�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Check</span> <span class="id" type="var">conj</span>.<br/>
<span class="comment">(* ===> forall P Q : Prop, P -> Q -> P /\ Q *)</span><br/>
<br/>
</div>
<div class="doc">
瘜冽�嚗onj��銝芾��乒�撠望�賡�P嚗憸嚗誑�����栽��
餈�銝銝枉/\Q���柴�
<div class="paragraph"> </div>
<a name="lab199"></a><h2 class="section">"撘" ��</h2>
�支�隞�銝芣�撠��箇�撱箇�韏瑚���蝞瘣�憭�餈摰���餈��血�銝
銝芸末憭��賑�賢�雿輻�賑撌脩��仿������交霂��急�����餈啜�
瘥霂湛�憒��格��臭�銝芸���嚗�隞祈憭���<span class="inlinecode"><span class="id" type="var">conj</span></span>餈葵�����嚗�
��餈隞乩�<span class="inlinecode"><span class="id" type="var">conj</span></span>�掩���伐�餈�霂�敶����撟嗡�撠�����銝支葵
�典���雿蛹銝支葵�閬��怨���摮��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">and_example</span> : <br/>
(0 = 0) <span style="font-family: arial;">∧</span> (4 = <span class="id" type="var">mult</span> 2 2).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">apply</span> <span class="id" type="var">conj</span>.<br/>
- <span class="comment">(* left *)</span> <span class="id" type="tactic">reflexivity</span>.<br/>
- <span class="comment">(* right *)</span> <span class="id" type="tactic">reflexivity</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
�箔��嫣噶嚗�隞砍隞亦<span class="inlinecode"><span class="id" type="tactic">split</span></span>雿蛹<span class="inlinecode"><span class="id" type="tactic">apply</span></span> <span class="inlinecode"><span class="id" type="var">conj</span></span>�憬�耦撘�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">and_example'</span> : <br/>
(0 = 0) <span style="font-family: arial;">∧</span> (4 = <span class="id" type="var">mult</span> 2 2).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">split</span>.<br/>
- <span class="comment">(* left *)</span> <span class="id" type="tactic">reflexivity</span>.<br/>
- <span class="comment">(* right *)</span> <span class="id" type="tactic">reflexivity</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab200"></a><h2 class="section">"瘨" ��</h2>
�詨��堆�<span class="inlinecode"><span class="id" type="tactic">destruct</span></span>餈�蝑�臭誑��撟嗉恣蝞�銝��葉��銝芸���
撘�敹◆���殷�撟嗡�撠�鈭��桐誑���耦撘溶�敶�霂���銝�銝准�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">proj1</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>, <br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> <span class="id" type="var">HQ</span>].<br/>
<span class="id" type="tactic">apply</span> <span class="id" type="var">HP</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab201"></a><h4 class="section">Exercise: 1 star, optional (proj2)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">proj2</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>, <br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">and_commut</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>, <br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> <span class="id" type="var">HQ</span>].<br/>
<span class="id" type="tactic">split</span>.<br/>
- <span class="comment">(* left *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">HQ</span>.<br/>
- <span class="comment">(* right *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">HP</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab202"></a><h4 class="section">Exercise: 2 stars (and_assoc)</h4>
瘜冽��其��Ｙ�餈葵霂�銝�<span class="inlinecode"><span class="id" type="tactic">destruct</span></span>雿輻��<i>撋�璅∪�<i>�臬�雿���<span class="inlinecode"><span class="id" type="var">H</span></span> <span class="inlinecode">:</span> <span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∧</span></span> <span class="inlinecode">(<span class="id" type="var">Q</span></span> <span class="inlinecode"><span style="font-family: arial;">∧</span></span> <span class="inlinecode"><span class="id" type="var">R</span>)</span>
閫����<span class="inlinecode"><span class="id" type="var">HP</span>:</span> <span class="inlinecode"><span class="id" type="var">P</span></span>嚗�<span class="inlinecode"><span class="id" type="var">HQ</span></span> <span class="inlinecode">:</span> <span class="inlinecode"><span class="id" type="var">Q</span></span>隞亙�<span class="inlinecode"><span class="id" type="var">HR</span></span> <span class="inlinecode">:</span> <span class="inlinecode"><span class="id" type="var">R</span></span>��餈�撘憪���銝芾���
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">and_assoc</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span> : <span class="id" type="keyword">Prop</span>, <br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">R</span>) <span style="font-family: arial;">→</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">∧</span> <span class="id" type="var">R</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> [<span class="id" type="var">HQ</span> <span class="id" type="var">HR</span>]].<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab203"></a><h1 class="section">Iff</h1>
<div class="paragraph"> </div>
蝞靘輻�"敶�隞�"餈蝚血�臭舅銝芾�怠�����
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">iff</span> (<span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>) := (<span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">∧</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">P</span>).<br/>
<br/>
<span class="id" type="keyword">Notation</span> "P <span style="font-family: arial;">↔</span> Q" := (<span class="id" type="var">iff</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span>) <br/>
(<span class="id" type="tactic">at</span> <span class="id" type="var">level</span> 95, <span class="id" type="var">no</span> <span class="id" type="var">associativity</span>) <br/>
: <span class="id" type="var">type_scope</span>.<br/>
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">iff_implies</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>, <br/>
(<span class="id" type="var">P</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">→</span> <span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HAB</span> <span class="id" type="var">HBA</span>]. <span class="id" type="tactic">apply</span> <span class="id" type="var">HAB</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">iff_sym</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>, <br/>
(<span class="id" type="var">P</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">→</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">P</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HAB</span> <span class="id" type="var">HBA</span>].<br/>
<span class="id" type="tactic">split</span>.<br/>
- <span class="comment">(* -> *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">HBA</span>.<br/>
- <span class="comment">(* <- *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">HAB</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab204"></a><h4 class="section">Exercise: 1 star, optional (iff_properties)</h4>
隞乩��Ｙ�<span class="inlinecode"><span style="font-family: arial;">↔</span></span>�笆蝘唳抒�霂�嚗�<span class="inlinecode"><span class="id" type="var">iff_sym</span></span>嚗�銝箏���霂�摰��芸���
���扼�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">iff_refl</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> : <span class="id" type="keyword">Prop</span>, <br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">iff_trans</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span> : <span class="id" type="keyword">Prop</span>, <br/>
(<span class="id" type="var">P</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">→</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">R</span>) <span style="font-family: arial;">→</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">↔</span> <span class="id" type="var">R</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
<br/>
</div>
<div class="doc">
�內嚗��銝��葉摮銝銝芬�銝�敶耦撘���嚗��臭誑雿輻<span class="inlinecode"><span class="id" type="tactic">inversion</span></span>
撠�圾銝箔舅銝芸��祉��游撘���銝蛹隞銋隞亥�銋�嚗� <font size=-2>☐</font>
<div class="paragraph"> </div>
Coq��鈭��乩�隞亦�怎��孵�憭�<span class="inlinecode"><span class="id" type="var">iff</span></span>撘僎�迨�其蝙�刻�鈭憸�
餈��函��嗅�隞仿撘餈���摨����閬蜀靘�嚗�<span class="inlinecode"><span class="id" type="tactic">rewrite</span></span>�支�
�臭誑��蝑�雿輻銋�嚗��臭誑��<span class="inlinecode"><span class="id" type="var">iff</span></span>撘蝙�具�
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab205"></a><h1 class="section">��嚗餉�"��"嚗�</h1>
<div class="paragraph"> </div>
<a name="lab206"></a><h2 class="section">摰��</h2>
<div class="paragraph"> </div>
��嚗餉�"��"嚗��臭誑鋡怠�銋蛹銝銝芸�蝥單批憸�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Inductive</span> <span class="id" type="var">or</span> (<span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>) : <span class="id" type="keyword">Prop</span> :=<br/>
| <span class="id" type="var">or_introl</span> : <span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">or</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span><br/>
| <span class="id" type="var">or_intror</span> : <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">or</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span>.<br/>
<br/>
<span class="id" type="keyword">Notation</span> "P <span style="font-family: arial;">∨</span> Q" := (<span class="id" type="var">or</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span>) : <span class="id" type="var">type_scope</span>.<br/>
<br/>
</div>
<div class="doc">
�斗��<span class="inlinecode"><span class="id" type="var">or_introl</span></span>��"蝐餃�"嚗�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Check</span> <span class="id" type="var">or_introl</span>.<br/>
<span class="comment">(* ===> forall P Q : Prop, P -> P \/ Q *)</span><br/>
<br/>
</div>
<div class="doc">
摰�銝葵颲�嚗�撠望�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>嚗憸�<span class="inlinecode"><span class="id" type="var">Q</span></span>隞亙��賡�<span class="inlinecode"><span class="id" type="var">P</span></span>���殷��嗅�
颲�賡�<span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∨</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>���桐�銝箄��潦�
�乩��亦���<span class="inlinecode"><span class="id" type="var">or_intror</span></span>�掩��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Check</span> <span class="id" type="var">or_intror</span>.<br/>
<span class="comment">(* ===> forall P Q : Prop, Q -> P \/ Q *)</span><br/>
<br/>
</div>
<div class="doc">
撠勗�<span class="inlinecode"><span class="id" type="var">or_introl</span></span>銝�瘀��芯�餈�閬�����<span class="inlinecode"><span class="id" type="var">P</span></span>���株<span class="inlinecode"><span class="id" type="var">Q</span></span>���柴�
<div class="paragraph"> </div>
�渲�銝��舅蝘��箏憸�<span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∨</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>���桃��孵�嚗�
<div class="paragraph"> </div>
<ul class="doclist">
<li> 蝏<span class="inlinecode"><span class="id" type="var">P</span></span>���殷�撟嗡�憯唳�雿�函�<span class="inlinecode"><span class="id" type="var">P</span></span>��霂��甇�<span class="inlinecode"><span class="id" type="var">or_introl</span></span>��
���踝�嚗���
</li>
<li> 蝏<span class="inlinecode"><span class="id" type="var">Q</span></span>���殷�撟嗥��<span class="inlinecode"><span class="id" type="var">or_intror</span></span>�扇��
</li>
</ul>
<div class="paragraph"> </div>
<a name="lab207"></a><h3 class="section"> </h3>
�蛹<span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∨</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>�舅銝芣���嚗笆銝銝芰掩�蛹<span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∨</span></span> <span class="inlinecode"><span class="id" type="var">Q</span></span>����銵�<span class="inlinecode"><span class="id" type="tactic">destruct</span></span>
撠���銝支葵摮��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">or_commut</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>,<br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> | <span class="id" type="var">HQ</span>].<br/>
- <span class="comment">(* left *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">or_intror</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HP</span>.<br/>
- <span class="comment">(* right *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">or_introl</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HQ</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
隞�典�憪�憪�隞砍�隡銝支葵雿蛹蝻拙����伐�<span class="inlinecode"><span class="id" type="var">left</span></span>��<span class="inlinecode"><span class="id" type="var">right</span></span>�亙��思誨��
<span class="inlinecode"><span class="id" type="tactic">apply</span></span> <span class="inlinecode"><span class="id" type="var">or_introl</span></span>��<span class="inlinecode"><span class="id" type="tactic">apply</span></span> <span class="inlinecode"><span class="id" type="var">or_intror</span></span>��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">or_commut'</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>,<br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> | <span class="id" type="var">HQ</span>].<br/>
- <span class="comment">(* left *)</span> <span class="id" type="var">right</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HP</span>.<br/>
- <span class="comment">(* right *)</span> <span class="id" type="var">left</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HQ</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">or_distributes_over_and_1</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span> : <span class="id" type="keyword">Prop</span>,<br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">R</span>) <span style="font-family: arial;">→</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">∧</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">R</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span>. <span class="id" type="tactic">intros</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> | [<span class="id" type="var">HQ</span> <span class="id" type="var">HR</span>]].<br/>
- <span class="comment">(* left *)</span> <span class="id" type="tactic">split</span>.<br/>
+ <span class="comment">(* left *)</span> <span class="id" type="var">left</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HP</span>.<br/>
+ <span class="comment">(* right *)</span> <span class="id" type="var">left</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HP</span>.<br/>
- <span class="comment">(* right *)</span> <span class="id" type="tactic">split</span>.<br/>
+ <span class="comment">(* left *)</span> <span class="id" type="var">right</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HQ</span>.<br/>
+ <span class="comment">(* right *)</span> <span class="id" type="var">right</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">HR</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab208"></a><h4 class="section">Exercise: 2 stars (or_distributes_over_and_2)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">or_distributes_over_and_2</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span> : <span class="id" type="keyword">Prop</span>,<br/>
(<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">∧</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">R</span>) <span style="font-family: arial;">→</span> <span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">R</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
<div class="paragraph"> </div>
<a name="lab209"></a><h4 class="section">Exercise: 1 star, optional (or_distributes_over_and)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">or_distributes_over_and</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">R</span> : <span class="id" type="keyword">Prop</span>,<br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> (<span class="id" type="var">Q</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">R</span>) <span style="font-family: arial;">↔</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">∧</span> (<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">R</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab210"></a><h2 class="section">撠�<span class="inlinecode"><span style="font-family: arial;">∧</span></span>��<span class="inlinecode"><span style="font-family: arial;">∨</span></span>銝�<span class="inlinecode"><span class="id" type="var">andb</span></span>��<span class="inlinecode"><span class="id" type="var">orb</span></span>�頂韏瑟</h2>
<div class="paragraph"> </div>
�賑撌脩��每oq�恣蝞�<span class="inlinecode"><span class="id" type="keyword">Type</span></span>嚗��餉�嚗�<span class="inlinecode"><span class="id" type="keyword">Prop</span></span>嚗��葉�鈭�銝�
雿輻鈭芋�����唳����血�銝銝迎�撣�餈���蝚�<span class="inlinecode"><span class="id" type="var">andb</span></span>��<span class="inlinecode"><span class="id" type="var">orb</span></span>嚗�
��堆��臬笆�餉�餈蝚�<span class="inlinecode"><span style="font-family: arial;">∧</span></span>��<span class="inlinecode"><span style="font-family: arial;">∨</span></span>�芋��隞乩�餈�霂湔�鈭�雿�銝�
<span class="inlinecode"><span class="id" type="var">andb</span></span>��<span class="inlinecode"><span class="id" type="var">orb</span></span>�冽�鈭��乩���銝箇�喟��亥�頧砍���餈�颲�詨�憸�
�抒�鈭�����餈�璅⊥��賢����游�蝎曄＆��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">andb_prop</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">b</span> <span class="id" type="var">c</span>,<br/>
<span class="id" type="var">andb</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> = <span class="id" type="var">true</span> <span style="font-family: arial;">→</span> <span class="id" type="var">b</span> = <span class="id" type="var">true</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">c</span> = <span class="id" type="var">true</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">b</span>.<br/>
- <span class="comment">(* b = true *)</span> <span class="id" type="tactic">destruct</span> <span class="id" type="var">c</span>.<br/>
+ <span class="comment">(* c = true *)</span> <span class="id" type="tactic">apply</span> <span class="id" type="var">conj</span>. <span class="id" type="tactic">reflexivity</span>. <span class="id" type="tactic">reflexivity</span>.<br/>
+ <span class="comment">(* c = false *)</span> <span class="id" type="tactic">inversion</span> <span class="id" type="var">H</span>.<br/>
- <span class="comment">(* b = false *)</span> <span class="id" type="tactic">inversion</span> <span class="id" type="var">H</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">andb_true_intro</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">b</span> <span class="id" type="var">c</span>,<br/>
<span class="id" type="var">b</span> = <span class="id" type="var">true</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">c</span> = <span class="id" type="var">true</span> <span style="font-family: arial;">→</span> <span class="id" type="var">andb</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> = <span class="id" type="var">true</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span>.<br/>
<span class="id" type="tactic">rewrite</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">rewrite</span> <span class="id" type="var">H0</span>. <span class="id" type="tactic">reflexivity</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab211"></a><h4 class="section">Exercise: 2 stars, optional (andb_false)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">andb_false</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">b</span> <span class="id" type="var">c</span>,<br/>
<span class="id" type="var">andb</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> = <span class="id" type="var">false</span> <span style="font-family: arial;">→</span> <span class="id" type="var">b</span> = <span class="id" type="var">false</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">c</span> = <span class="id" type="var">false</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab212"></a><h4 class="section">Exercise: 2 stars, optional (orb_false)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">orb_prop</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">b</span> <span class="id" type="var">c</span>,<br/>
<span class="id" type="var">orb</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> = <span class="id" type="var">true</span> <span style="font-family: arial;">→</span> <span class="id" type="var">b</span> = <span class="id" type="var">true</span> <span style="font-family: arial;">∨</span> <span class="id" type="var">c</span> = <span class="id" type="var">true</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab213"></a><h4 class="section">Exercise: 2 stars, optional (orb_false_elim)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">orb_false_elim</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">b</span> <span class="id" type="var">c</span>,<br/>
<span class="id" type="var">orb</span> <span class="id" type="var">b</span> <span class="id" type="var">c</span> = <span class="id" type="var">false</span> <span style="font-family: arial;">→</span> <span class="id" type="var">b</span> = <span class="id" type="var">false</span> <span style="font-family: arial;">∧</span> <span class="id" type="var">c</span> = <span class="id" type="var">false</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab214"></a><h1 class="section">�撘�</h1>
<div class="paragraph"> </div>
�每oq銝剔��曉��臭誑�其�銝芣瓷������蝥喳�銋��賡�銵函內��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Inductive</span> <span class="id" type="var">False</span> : <span class="id" type="keyword">Prop</span> := .<br/>
<br/>
</div>
<div class="doc">
�函閫�<span class="inlinecode"><span class="id" type="var">False</span></span>�臭�銝芣�瘜��箄��桃��賡���
<div class="paragraph"> </div>
�蛹<span class="inlinecode"><span class="id" type="var">False</span></span>瘝⊥���嚗笆銝銝芰掩�蛹<span class="inlinecode"><span class="id" type="var">False</span></span>��霈曇�銵�瞍�銝�
��隞颱�摮���望迨�賑敺誑蝡霂�隞颱��格���
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">False_implies_nonsense</span> :<br/>
<span class="id" type="var">False</span> <span style="font-family: arial;">→</span> 2 + 2 = 5.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">contra</span>.<br/>
<span class="id" type="tactic">inversion</span> <span class="id" type="var">contra</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
摰憒�鈭抒�����<span class="inlinecode"><span class="id" type="tactic">inversion</span></span>蝑撠�<span class="inlinecode"><span class="id" type="var">contra</span></span>�圾��銝芸�賢�啁��
撟嗡蛹瘥�蝘��萇���銝芸��格���銝�<span class="inlinecode"><span class="id" type="var">contra</span></span>雿蛹<span class="inlinecode"><span class="id" type="var">False</span></span>����<i>撟嗆瓷�
�航�箇���蛛��迨餈�瘝⊥��航�箇���格�嚗���甇文�隞亙���
<div class="paragraph"> </div>
<a name="lab215"></a><h3 class="section"> </h3>
�詨��堆�霂�<span class="inlinecode"><span class="id" type="var">False</span></span>�銝�寞�撠望霈拙���銝�銝剖��刻鬲霂舀����橘�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">nonsense_implies_False</span> :<br/>
2 + 2 = 5 <span style="font-family: arial;">→</span> <span class="id" type="var">False</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">contra</span>.<br/>
<span class="id" type="tactic">inversion</span> <span class="id" type="var">contra</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
鈭�銝�<span class="inlinecode"><span class="id" type="var">False_implies_nonsense</span></span>���僎銝�隞颱��孵��◤霂��鬲霂舀��喉�
�迨摰隞亙�摰寞��啗◤銝�砍�撟嗡����臭誑�典隞餅��賡�<span class="inlinecode"><span class="id" type="var">P</span></span>銝�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">ex_falso_quodlibet</span> : <span style="font-family: arial;">∀</span>(<span class="id" type="var">P</span>:<span class="id" type="keyword">Prop</span>),<br/>
<span class="id" type="var">False</span> <span style="font-family: arial;">→</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">contra</span>.<br/>
<span class="id" type="tactic">inversion</span> <span class="id" type="var">contra</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<i>ex falso quodlibet_�舀�銝�嚗����Ｘ��嚗�"隞鬲霂臬���質���
隞颱�雿閬����賡�"��銝摰�銋◤蝘唬�<i>���<i>��
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab216"></a><h2 class="section">��</h2>
<div class="paragraph"> </div>
�蛹�賑撌脩��每oq銝剖�銋��撘��犖銋捂隡�仿��賑�臬�賢���
�詨��撘�銋��潦�隞祈憭�銋���
<div class="paragraph"> </div>
<a name="lab217"></a><h4 class="section">Exercise: 2 stars, advanced (True)</h4>
撠�<span class="inlinecode"><span class="id" type="var">True</span></span>摰�銝箔�銝芸�蝥喳�銋��賡���隞閫�霂�<span class="inlinecode"><span class="id" type="var">True</span></span>摨砲�臭�銝�
�賢像�∪蝏霂�憸�
</div>
<div class="code code-tight">
<br/>
<span class="comment">(* FILL IN HERE *)</span><br/>
</div>
<div class="doc">
<font size=-2>☐</font>
<div class="paragraph"> </div>
�嗉���隞砍�隡�撣訾蝙�函�<span class="inlinecode"><span class="id" type="var">False</span></span>嚗�<span class="inlinecode"><span class="id" type="var">True</span></span>��鋡思蝙�典�停�芾澈��嚗�
摰銝芾�鈭像�∴��迨銋�敺�頞��������其�銝箄������嗡�銝��思遙雿�
��縑�胯��臬摰�憭��蝙�典鈭隞嗅���<span class="inlinecode"><span class="id" type="keyword">Prop</span></span>�����銝�
擃<span class="inlinecode"><span class="id" type="keyword">Prop</span></span>���啁��嗅�<span class="inlinecode"><span class="id" type="var">True</span></span>�臬����函���
</div>
<div class="code code-tight">
<br/>
</div>
<div class="doc">
<a name="lab218"></a><h1 class="section">�血�</h1>
<div class="paragraph"> </div>
�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>�餉�銝�銵亙�雿�<span class="inlinecode"><span class="id" type="var">not</span></span> <span class="inlinecode"><span class="id" type="var">P</span></span>嚗��蝙�函憬�耦撘�<span class="inlinecode">竅<span class="id" type="var">P</span></span>嚗�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">not</span> (<span class="id" type="var">P</span>:<span class="id" type="keyword">Prop</span>) := <span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">False</span>.<br/>
<br/>
</div>
<div class="doc">
�刻����閫嚗���<span class="inlinecode"><span class="id" type="var">P</span></span>銝蛹���遙雿憸��<span class="inlinecode"><span class="id" type="var">False</span></span>嚗�
�質�典�霈�<span class="inlinecode"><span class="id" type="var">P</span></span>���萎�霂���
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Notation</span> "竅 x" := (<span class="id" type="var">not</span> <span class="id" type="var">x</span>) : <span class="id" type="var">type_scope</span>.<br/>
<br/>
<span class="id" type="keyword">Check</span> <span class="id" type="var">not</span>.<br/>
<span class="comment">(* ===> Prop -> Prop *)</span><br/>
<br/>
</div>
<div class="doc">
�其��臬Coq銝剖��摰����閬��寧�銋��嗅雿蹂�摰�
銝箔�銋�鈭憸蛹���冽�撘憪��嗅����挽蝵株悟Coq蝟餌��亙�餈�
�嫣��舀�銝�孵�曄�����銝鈭虜閫�摰�霂�嚗�銝箏餈����剛澈��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">not_False</span> : <br/>
竅 <span class="id" type="var">False</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="id" type="tactic">unfold</span> <span class="id" type="var">not</span>. <span class="id" type="tactic">intros</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">inversion</span> <span class="id" type="var">H</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab219"></a><h3 class="section"> </h3>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">contradiction_implies_anything</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>,<br/>
(<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> 竅<span class="id" type="var">P</span>) <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">Q</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">destruct</span> <span class="id" type="var">H</span> <span class="id" type="keyword">as</span> [<span class="id" type="var">HP</span> <span class="id" type="var">HNA</span>]. <span class="id" type="tactic">unfold</span> <span class="id" type="var">not</span> <span class="id" type="keyword">in</span> <span class="id" type="var">HNA</span>.<br/>
<span class="id" type="tactic">apply</span> <span class="id" type="var">HNA</span> <span class="id" type="keyword">in</span> <span class="id" type="var">HP</span>. <span class="id" type="tactic">inversion</span> <span class="id" type="var">HP</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">double_neg</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> : <span class="id" type="keyword">Prop</span>,<br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">→</span> ~~<span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">unfold</span> <span class="id" type="var">not</span>. <span class="id" type="tactic">intros</span> <span class="id" type="var">G</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">G</span>. <span class="id" type="tactic">apply</span> <span class="id" type="var">H</span>. <span class="id" type="keyword">Qed</span>.<br/>
<br/>
</div>
<div class="doc">
<a name="lab220"></a><h4 class="section">Exercise: 2 stars, advanced (double_neg_inf)</h4>
���賡�<span class="inlinecode"><span class="id" type="var">double_neg</span></span>��敶Ｗ�霂�嚗�
<i>摰�_: 撖嫣�隞餅��賡�<span class="inlinecode"><span class="id" type="var">P</span></span>嚗�<span class="inlinecode"><span class="id" type="var">P</span></span>�游<span class="inlinecode">~~<span class="id" type="var">P</span></span>��
<i>霂�_:
<span class="comment">(* FILL IN HERE *)</span><br/>
<font size=-2>☐</font>
<div class="paragraph"> </div>
<a name="lab221"></a><h4 class="section">Exercise: 2 stars (contrapositive)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">contrapositive</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span> : <span class="id" type="keyword">Prop</span>,<br/>
(<span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">Q</span>) <span style="font-family: arial;">→</span> (竅<span class="id" type="var">Q</span> <span style="font-family: arial;">→</span> 竅<span class="id" type="var">P</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
<div class="paragraph"> </div>
<a name="lab222"></a><h4 class="section">Exercise: 1 star (not_both_true_and_false)</h4>
</div>
<div class="code code-space">
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">not_both_true_and_false</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> : <span class="id" type="keyword">Prop</span>,<br/>
竅 (<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> 竅<span class="id" type="var">P</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
</div>
<div class="doc">
<font size=-2>☐</font>
<div class="paragraph"> </div>
<a name="lab223"></a><h4 class="section">Exercise: 1 star, advanced (informal_not_PNP)</h4>
���賡�<span class="inlinecode"><span style="font-family: arial;">∀</span></span> <span class="inlinecode"><span class="id" type="var">P</span></span> <span class="inlinecode">:</span> <span class="inlinecode"><span class="id" type="keyword">Prop</span>,</span> <span class="inlinecode">~(<span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∧</span></span> <span class="inlinecode">竅<span class="id" type="var">P</span>)</span>��敶Ｗ�霂�
</div>
<div class="code code-tight">
<br/>
<span class="comment">(* FILL IN HERE *)</span><br/>
</div>
<div class="doc">
<font size=-2>☐</font>
<div class="paragraph"> </div>
<a name="lab224"></a><h3 class="section">�折餉�</h3>
瘜冽�嚗�鈭蝏�餉�銝�蝡�摰��每oq���折餉�銝剜銝霂���
靘�霂湛�霈拇�隞祉����Ｚ�銝芾��憒���餈�銝�色�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">classic_double_neg</span> : <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> : <span class="id" type="keyword">Prop</span>,<br/>
~~<span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* WORKED IN CLASS *)</span><br/>
<span class="id" type="tactic">intros</span> <span class="id" type="var">P</span> <span class="id" type="var">H</span>. <span class="id" type="tactic">unfold</span> <span class="id" type="var">not</span> <span class="id" type="keyword">in</span> <span class="id" type="var">H</span>.<br/>
<span class="comment">(* �嗅��ｇ��賑瘝⊥����箔�<span class="inlinecode"><span class="id" type="var">P</span></span>���栽���賡�<span class="inlinecode">竅<span class="id" type="var">P</span></span>���柴�*)</span><br/>
<span class="id" type="keyword">Abort</span>.<br/>
</div>
<div class="doc">
<a name="lab225"></a><h4 class="section">Exercise: 5 stars, advanced, optional (classical_axioms)</h4>
撖嫣�����洽���犖嚗���銝銝芣��杭oq'Art嚗洵123憿蛛���銋�
銝�臭��∪虜撣貉◤霈支蛹�臬�颱�蝏�餉�嚗�Coq"�蔭"���折餉�
�詨笆嚗�霂剖�Coq銝剜�隞祆�瘜���隞穿�雿憒��賑撣�憭���
蝏�餉�銝��桅�嚗�隞祈憭�摰賑銋葉�遙���乩�銝箔�銝芣瓷��
���祉���Coq銋葉�������湔扼�霂�鈭葵�賡�鈭蝑遠��
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">peirce</span> := <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span>: <span class="id" type="keyword">Prop</span>, <br/>
((<span class="id" type="var">P</span><span style="font-family: arial;">→</span><span class="id" type="var">Q</span>)<span style="font-family: arial;">→</span><span class="id" type="var">P</span>)<span style="font-family: arial;">→</span><span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">classic</span> := <span style="font-family: arial;">∀</span><span class="id" type="var">P</span>:<span class="id" type="keyword">Prop</span>, <br/>
~~<span class="id" type="var">P</span> <span style="font-family: arial;">→</span> <span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">excluded_middle</span> := <span style="font-family: arial;">∀</span><span class="id" type="var">P</span>:<span class="id" type="keyword">Prop</span>, <br/>
<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> 竅<span class="id" type="var">P</span>.<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">de_morgan_not_and_not</span> := <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span>:<span class="id" type="keyword">Prop</span>, <br/>
~(~<span class="id" type="var">P</span> <span style="font-family: arial;">∧</span> 竅<span class="id" type="var">Q</span>) <span style="font-family: arial;">→</span> <span class="id" type="var">P</span><span style="font-family: arial;">∨</span><span class="id" type="var">Q</span>.<br/>
<span class="id" type="keyword">Definition</span> <span class="id" type="var">implies_to_or</span> := <span style="font-family: arial;">∀</span><span class="id" type="var">P</span> <span class="id" type="var">Q</span>:<span class="id" type="keyword">Prop</span>, <br/>
(<span class="id" type="var">P</span><span style="font-family: arial;">→</span><span class="id" type="var">Q</span>) <span style="font-family: arial;">→</span> (竅<span class="id" type="var">P</span><span style="font-family: arial;">∨</span><span class="id" type="var">Q</span>).<br/>
<br/>
<span class="comment">(* FILL IN HERE *)</span><br/>
</div>
<div class="doc">
<font size=-2>☐</font>
<div class="paragraph"> </div>
<a name="lab226"></a><h4 class="section">Exercise: 3 stars (excluded_middle_irrefutable)</h4>
餈�摰��游鈭�銝芯�摰�撖嫣�隞餅�<i>�孵���<i>�賡�<span class="inlinecode"><span class="id" type="var">P</span></span>嚗隞交溶�遙��銝芸�文���
�祉�嚗�憒秩�葉敺�銝銝芸�靘������冽扼蛹隞銋��蛹�賑銝霂�餈銝
銝芸���血�嚗���隞祈憭�銋�嚗�隞砍�隡��嗆�<span class="inlinecode">竅</span> <span class="inlinecode">(<span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∨</span></span> <span class="inlinecode"><span class="id" type="var">P</span>)</span>��<span class="inlinecode">竅</span> <span class="inlinecode">竅</span> <span class="inlinecode">(<span class="id" type="var">P</span></span> <span class="inlinecode"><span style="font-family: arial;">∨</span></span> <span class="inlinecode">竅<span class="id" type="var">P</span>)</span>嚗�
���臭�銝芰��整�
</div>
<div class="code code-tight">
<br/>
<span class="id" type="keyword">Theorem</span> <span class="id" type="var">excluded_middle_irrefutable</span>: <span style="font-family: arial;">∀</span>(<span class="id" type="var">P</span>:<span class="id" type="keyword">Prop</span>), 竅 竅 (<span class="id" type="var">P</span> <span style="font-family: arial;">∨</span> 竅 <span class="id" type="var">P</span>).<br/>
<span class="id" type="keyword">Proof</span>.<br/>
<span class="comment">(* FILL IN HERE *)</span> <span class="id" type="var">Admitted</span>.<br/>
<br/>
</div>