1 | include "basics/lists/list.ma". |
---|
2 | include "basics/types.ma". |
---|
3 | include "arithmetics/nat.ma". |
---|
4 | include "basics/russell.ma". |
---|
5 | |
---|
6 | (* let's implement a daemon not used by automation *) |
---|
7 | inductive DAEMONXXX: Type[0] ≝ K1DAEMONXXX: DAEMONXXX | K2DAEMONXXX: DAEMONXXX. |
---|
8 | axiom IMPOSSIBLE: K1DAEMONXXX = K2DAEMONXXX. |
---|
9 | example daemon: False. generalize in match IMPOSSIBLE; #IMPOSSIBLE destruct(IMPOSSIBLE) qed. |
---|
10 | example not_implemented: False. cases daemon qed. |
---|
11 | |
---|
12 | notation "⊥" with precedence 90 |
---|
13 | for @{ match ? in False with [ ] }. |
---|
14 | notation "Ⓧ" with precedence 90 |
---|
15 | for @{ λabs.match abs in False with [ ] }. |
---|
16 | |
---|
17 | |
---|
18 | definition ltb ≝ |
---|
19 | λm, n: nat. |
---|
20 | leb (S m) n. |
---|
21 | |
---|
22 | definition geb ≝ |
---|
23 | λm, n: nat. |
---|
24 | leb n m. |
---|
25 | |
---|
26 | definition gtb ≝ |
---|
27 | λm, n: nat. |
---|
28 | ltb n m. |
---|
29 | |
---|
30 | (* dpm: unless I'm being stupid, this isn't defined in the stdlib? *) |
---|
31 | let rec eq_nat (n: nat) (m: nat) on n: bool ≝ |
---|
32 | match n with |
---|
33 | [ O ⇒ match m with [ O ⇒ true | _ ⇒ false ] |
---|
34 | | S n' ⇒ match m with [ S m' ⇒ eq_nat n' m' | _ ⇒ false ] |
---|
35 | ]. |
---|
36 | |
---|
37 | let rec forall |
---|
38 | (A: Type[0]) (f: A → bool) (l: list A) |
---|
39 | on l ≝ |
---|
40 | match l with |
---|
41 | [ nil ⇒ true |
---|
42 | | cons hd tl ⇒ f hd ∧ forall A f tl |
---|
43 | ]. |
---|
44 | |
---|
45 | let rec prefix |
---|
46 | (A: Type[0]) (k: nat) (l: list A) |
---|
47 | on l ≝ |
---|
48 | match l with |
---|
49 | [ nil ⇒ [ ] |
---|
50 | | cons hd tl ⇒ |
---|
51 | match k with |
---|
52 | [ O ⇒ [ ] |
---|
53 | | S k' ⇒ hd :: prefix A k' tl |
---|
54 | ] |
---|
55 | ]. |
---|
56 | |
---|
57 | let rec fold_left2 |
---|
58 | (A: Type[0]) (B: Type[0]) (C: Type[0]) (f: A → B → C → A) (accu: A) |
---|
59 | (left: list B) (right: list C) (proof: |left| = |right|) |
---|
60 | on left: A ≝ |
---|
61 | match left return λx. |x| = |right| → A with |
---|
62 | [ nil ⇒ λnil_prf. |
---|
63 | match right return λx. |[ ]| = |x| → A with |
---|
64 | [ nil ⇒ λnil_nil_prf. accu |
---|
65 | | cons hd tl ⇒ λcons_nil_absrd. ? |
---|
66 | ] nil_prf |
---|
67 | | cons hd tl ⇒ λcons_prf. |
---|
68 | match right return λx. |hd::tl| = |x| → A with |
---|
69 | [ nil ⇒ λcons_nil_absrd. ? |
---|
70 | | cons hd' tl' ⇒ λcons_cons_prf. |
---|
71 | fold_left2 … f (f accu hd hd') tl tl' ? |
---|
72 | ] cons_prf |
---|
73 | ] proof. |
---|
74 | [ 1: normalize in cons_nil_absrd; |
---|
75 | destruct(cons_nil_absrd) |
---|
76 | | 2: normalize in cons_nil_absrd; |
---|
77 | destruct(cons_nil_absrd) |
---|
78 | | 3: normalize in cons_cons_prf; |
---|
79 | @injective_S |
---|
80 | assumption |
---|
81 | ] |
---|
82 | qed. |
---|
83 | |
---|
84 | let rec remove_n_first_internal |
---|
85 | (i: nat) (A: Type[0]) (l: list A) (n: nat) |
---|
86 | on l ≝ |
---|
87 | match l with |
---|
88 | [ nil ⇒ [ ] |
---|
89 | | cons hd tl ⇒ |
---|
90 | match eq_nat i n with |
---|
91 | [ true ⇒ l |
---|
92 | | _ ⇒ remove_n_first_internal (S i) A tl n |
---|
93 | ] |
---|
94 | ]. |
---|
95 | |
---|
96 | definition remove_n_first ≝ |
---|
97 | λA: Type[0]. |
---|
98 | λn: nat. |
---|
99 | λl: list A. |
---|
100 | remove_n_first_internal 0 A l n. |
---|
101 | |
---|
102 | let rec foldi_from_until_internal |
---|
103 | (A: Type[0]) (i: nat) (res: ?) (rem: list A) (m: nat) (f: nat → list A → A → list A) |
---|
104 | on rem ≝ |
---|
105 | match rem with |
---|
106 | [ nil ⇒ res |
---|
107 | | cons e tl ⇒ |
---|
108 | match geb i m with |
---|
109 | [ true ⇒ res |
---|
110 | | _ ⇒ foldi_from_until_internal A (S i) (f i res e) tl m f |
---|
111 | ] |
---|
112 | ]. |
---|
113 | |
---|
114 | definition foldi_from_until ≝ |
---|
115 | λA: Type[0]. |
---|
116 | λn: nat. |
---|
117 | λm: nat. |
---|
118 | λf: ?. |
---|
119 | λa: ?. |
---|
120 | λl: ?. |
---|
121 | foldi_from_until_internal A 0 a (remove_n_first A n l) m f. |
---|
122 | |
---|
123 | definition foldi_from ≝ |
---|
124 | λA: Type[0]. |
---|
125 | λn. |
---|
126 | λf. |
---|
127 | λa. |
---|
128 | λl. |
---|
129 | foldi_from_until A n (|l|) f a l. |
---|
130 | |
---|
131 | definition foldi_until ≝ |
---|
132 | λA: Type[0]. |
---|
133 | λm. |
---|
134 | λf. |
---|
135 | λa. |
---|
136 | λl. |
---|
137 | foldi_from_until A 0 m f a l. |
---|
138 | |
---|
139 | definition foldi ≝ |
---|
140 | λA: Type[0]. |
---|
141 | λf. |
---|
142 | λa. |
---|
143 | λl. |
---|
144 | foldi_from_until A 0 (|l|) f a l. |
---|
145 | |
---|
146 | definition hd_safe ≝ |
---|
147 | λA: Type[0]. |
---|
148 | λl: list A. |
---|
149 | λproof: 0 < |l|. |
---|
150 | match l return λx. 0 < |x| → A with |
---|
151 | [ nil ⇒ λnil_absrd. ? |
---|
152 | | cons hd tl ⇒ λcons_prf. hd |
---|
153 | ] proof. |
---|
154 | normalize in nil_absrd; |
---|
155 | cases(not_le_Sn_O 0) |
---|
156 | #HYP |
---|
157 | cases(HYP nil_absrd) |
---|
158 | qed. |
---|
159 | |
---|
160 | definition tail_safe ≝ |
---|
161 | λA: Type[0]. |
---|
162 | λl: list A. |
---|
163 | λproof: 0 < |l|. |
---|
164 | match l return λx. 0 < |x| → list A with |
---|
165 | [ nil ⇒ λnil_absrd. ? |
---|
166 | | cons hd tl ⇒ λcons_prf. tl |
---|
167 | ] proof. |
---|
168 | normalize in nil_absrd; |
---|
169 | cases(not_le_Sn_O 0) |
---|
170 | #HYP |
---|
171 | cases(HYP nil_absrd) |
---|
172 | qed. |
---|
173 | |
---|
174 | let rec safe_split |
---|
175 | (A: Type[0]) (l: list A) (index: nat) (proof: index ≤ |l|) |
---|
176 | on index ≝ |
---|
177 | match index return λx. x ≤ |l| → (list A) × (list A) with |
---|
178 | [ O ⇒ λzero_prf. 〈[], l〉 |
---|
179 | | S index' ⇒ λsucc_prf. |
---|
180 | match l return λx. S index' ≤ |x| → (list A) × (list A) with |
---|
181 | [ nil ⇒ λnil_absrd. ? |
---|
182 | | cons hd tl ⇒ λcons_prf. |
---|
183 | let 〈l1, l2〉 ≝ safe_split A tl index' ? in |
---|
184 | 〈hd :: l1, l2〉 |
---|
185 | ] succ_prf |
---|
186 | ] proof. |
---|
187 | [1: normalize in nil_absrd; |
---|
188 | cases(not_le_Sn_O index') |
---|
189 | #HYP |
---|
190 | cases(HYP nil_absrd) |
---|
191 | |2: normalize in cons_prf; |
---|
192 | @le_S_S_to_le |
---|
193 | assumption |
---|
194 | ] |
---|
195 | qed. |
---|
196 | |
---|
197 | let rec nth_safe |
---|
198 | (elt_type: Type[0]) (index: nat) (the_list: list elt_type) |
---|
199 | (proof: index < | the_list |) |
---|
200 | on index ≝ |
---|
201 | match index return λs. s < | the_list | → elt_type with |
---|
202 | [ O ⇒ |
---|
203 | match the_list return λt. 0 < | t | → elt_type with |
---|
204 | [ nil ⇒ λnil_absurd. ? |
---|
205 | | cons hd tl ⇒ λcons_proof. hd |
---|
206 | ] |
---|
207 | | S index' ⇒ |
---|
208 | match the_list return λt. S index' < | t | → elt_type with |
---|
209 | [ nil ⇒ λnil_absurd. ? |
---|
210 | | cons hd tl ⇒ |
---|
211 | λcons_proof. nth_safe elt_type index' tl ? |
---|
212 | ] |
---|
213 | ] proof. |
---|
214 | [ normalize in nil_absurd; |
---|
215 | cases (not_le_Sn_O 0) |
---|
216 | #ABSURD |
---|
217 | elim (ABSURD nil_absurd) |
---|
218 | | normalize in nil_absurd; |
---|
219 | cases (not_le_Sn_O (S index')) |
---|
220 | #ABSURD |
---|
221 | elim (ABSURD nil_absurd) |
---|
222 | | normalize in cons_proof; |
---|
223 | @le_S_S_to_le |
---|
224 | assumption |
---|
225 | ] |
---|
226 | qed. |
---|
227 | |
---|
228 | lemma shift_nth_safe: |
---|
229 | ∀T,i,l2,l1,K1,K2. |
---|
230 | nth_safe T i l1 K1 = nth_safe T (i+|l2|) (l2@l1) K2. |
---|
231 | #T #i #l2 elim l2 normalize |
---|
232 | [ #l1 #K1 <plus_n_O #K2 % |
---|
233 | | #hd #tl #IH #l1 #K1 <plus_n_Sm #K2 change with (? < ?) in K1; change with (? < ?) in K2; |
---|
234 | whd in ⊢ (???%); @IH ] |
---|
235 | qed. |
---|
236 | |
---|
237 | lemma shift_nth_prefix: |
---|
238 | ∀T,l1,i,l2,K1,K2. |
---|
239 | nth_safe T i l1 K1 = nth_safe T i (l1@l2) K2. |
---|
240 | #T #l1 elim l1 normalize |
---|
241 | [ |
---|
242 | #i #l1 #K1 cases(lt_to_not_zero … K1) |
---|
243 | | |
---|
244 | #hd #tl #IH #i #l2 |
---|
245 | cases i |
---|
246 | [ |
---|
247 | // |
---|
248 | | |
---|
249 | #i' #K1 #K2 whd in ⊢ (??%%); |
---|
250 | @IH |
---|
251 | ] |
---|
252 | ] |
---|
253 | qed. |
---|
254 | |
---|
255 | (*CSC: practically equal to shift_nth_safe but for commutation |
---|
256 | of addition. One of the two lemmas should disappear. *) |
---|
257 | lemma nth_safe_prepend: |
---|
258 | ∀A,l1,l2,j.∀H:j<|l2|.∀K:|l1|+j<|(l1@l2)|. |
---|
259 | nth_safe A j l2 H =nth_safe A (|l1|+j) (l1@l2) K. |
---|
260 | #A #l1 #l2 #j #H >commutative_plus @shift_nth_safe |
---|
261 | qed. |
---|
262 | |
---|
263 | lemma nth_safe_cons: |
---|
264 | ∀A,hd,tl,l2,j,j_ok,Sj_ok. |
---|
265 | nth_safe A j (tl@l2) j_ok =nth_safe A (1+j) (hd::tl@l2) Sj_ok. |
---|
266 | // |
---|
267 | qed. |
---|
268 | |
---|
269 | lemma eq_nth_safe_proof_irrelevant: |
---|
270 | ∀A,l,i,i_ok,i_ok'. |
---|
271 | nth_safe A l i i_ok = nth_safe A l i i_ok'. |
---|
272 | #A #l #i #i_ok #i_ok' % |
---|
273 | qed. |
---|
274 | |
---|
275 | lemma nth_safe_append: |
---|
276 | ∀A,l,n,n_ok. |
---|
277 | ∃pre,suff. |
---|
278 | (pre @ [nth_safe A n l n_ok]) @ suff = l. |
---|
279 | #A #l elim l normalize |
---|
280 | [ #n #abs cases (absurd ? abs (not_le_Sn_O ?)) |
---|
281 | | #hd #tl #IH #n cases n normalize |
---|
282 | [ #_ %{[]} /2/ |
---|
283 | | #m #m_ok cases (IH m ?) |
---|
284 | [ #pre * #suff #EQ %{(hd::pre)} %{suff} <EQ in ⊢ (???%); % | skip ]] |
---|
285 | qed. |
---|
286 | |
---|
287 | definition last_safe ≝ |
---|
288 | λelt_type: Type[0]. |
---|
289 | λthe_list: list elt_type. |
---|
290 | λproof : 0 < | the_list |. |
---|
291 | nth_safe elt_type (|the_list| - 1) the_list ?. |
---|
292 | normalize /2 by lt_plus_to_minus/ |
---|
293 | qed. |
---|
294 | |
---|
295 | let rec reduce |
---|
296 | (A: Type[0]) (B: Type[0]) (left: list A) (right: list B) on left ≝ |
---|
297 | match left with |
---|
298 | [ nil ⇒ 〈〈[ ], [ ]〉, 〈[ ], right〉〉 |
---|
299 | | cons hd tl ⇒ |
---|
300 | match right with |
---|
301 | [ nil ⇒ 〈〈[ ], left〉, 〈[ ], [ ]〉〉 |
---|
302 | | cons hd' tl' ⇒ |
---|
303 | let 〈cleft, cright〉 ≝ reduce A B tl tl' in |
---|
304 | let 〈commonl, restl〉 ≝ cleft in |
---|
305 | let 〈commonr, restr〉 ≝ cright in |
---|
306 | 〈〈hd :: commonl, restl〉, 〈hd' :: commonr, restr〉〉 |
---|
307 | ] |
---|
308 | ]. |
---|
309 | |
---|
310 | (* |
---|
311 | axiom reduce_strong: |
---|
312 | ∀A: Type[0]. |
---|
313 | ∀left: list A. |
---|
314 | ∀right: list A. |
---|
315 | Σret: ((list A) × (list A)) × ((list A) × (list A)). | \fst (\fst ret) | = | \fst (\snd ret) |. |
---|
316 | *) |
---|
317 | |
---|
318 | let rec reduce_strong |
---|
319 | (A: Type[0]) (B: Type[0]) (left: list A) (right: list B) |
---|
320 | on left : Σret: ((list A) × (list A)) × ((list B) × (list B)). |\fst (\fst ret)| = |\fst (\snd ret)| ≝ |
---|
321 | match left with |
---|
322 | [ nil ⇒ 〈〈[ ], [ ]〉, 〈[ ], right〉〉 |
---|
323 | | cons hd tl ⇒ |
---|
324 | match right with |
---|
325 | [ nil ⇒ 〈〈[ ], left〉, 〈[ ], [ ]〉〉 |
---|
326 | | cons hd' tl' ⇒ |
---|
327 | let 〈cleft, cright〉 ≝ pi1 ?? (reduce_strong A B tl tl') in |
---|
328 | let 〈commonl, restl〉 ≝ cleft in |
---|
329 | let 〈commonr, restr〉 ≝ cright in |
---|
330 | 〈〈hd :: commonl, restl〉, 〈hd' :: commonr, restr〉〉 |
---|
331 | ] |
---|
332 | ]. |
---|
333 | [ 1: normalize % |
---|
334 | | 2: normalize % |
---|
335 | | 3: normalize >p3 in p2; >p4 cases (reduce_strong … tl tl1) normalize |
---|
336 | #X #H #EQ destruct // ] |
---|
337 | qed. |
---|
338 | |
---|
339 | let rec map2_opt |
---|
340 | (A: Type[0]) (B: Type[0]) (C: Type[0]) (f: A → B → C) |
---|
341 | (left: list A) (right: list B) on left ≝ |
---|
342 | match left with |
---|
343 | [ nil ⇒ |
---|
344 | match right with |
---|
345 | [ nil ⇒ Some ? (nil C) |
---|
346 | | _ ⇒ None ? |
---|
347 | ] |
---|
348 | | cons hd tl ⇒ |
---|
349 | match right with |
---|
350 | [ nil ⇒ None ? |
---|
351 | | cons hd' tl' ⇒ |
---|
352 | match map2_opt A B C f tl tl' with |
---|
353 | [ None ⇒ None ? |
---|
354 | | Some tail ⇒ Some ? (f hd hd' :: tail) |
---|
355 | ] |
---|
356 | ] |
---|
357 | ]. |
---|
358 | |
---|
359 | let rec map2 |
---|
360 | (A: Type[0]) (B: Type[0]) (C: Type[0]) (f: A → B → C) |
---|
361 | (left: list A) (right: list B) (proof: | left | = | right |) on left ≝ |
---|
362 | match left return λx. | x | = | right | → list C with |
---|
363 | [ nil ⇒ |
---|
364 | match right return λy. | [] | = | y | → list C with |
---|
365 | [ nil ⇒ λnil_prf. nil C |
---|
366 | | _ ⇒ λcons_absrd. ? |
---|
367 | ] |
---|
368 | | cons hd tl ⇒ |
---|
369 | match right return λy. | hd::tl | = | y | → list C with |
---|
370 | [ nil ⇒ λnil_absrd. ? |
---|
371 | | cons hd' tl' ⇒ λcons_prf. (f hd hd') :: map2 A B C f tl tl' ? |
---|
372 | ] |
---|
373 | ] proof. |
---|
374 | [1: normalize in cons_absrd; |
---|
375 | destruct(cons_absrd) |
---|
376 | |2: normalize in nil_absrd; |
---|
377 | destruct(nil_absrd) |
---|
378 | |3: normalize in cons_prf; |
---|
379 | destruct(cons_prf) |
---|
380 | assumption |
---|
381 | ] |
---|
382 | qed. |
---|
383 | |
---|
384 | let rec map3 |
---|
385 | (A: Type[0]) (B: Type[0]) (C: Type[0]) (D: Type[0]) (f: A → B → C → D) |
---|
386 | (left: list A) (centre: list B) (right: list C) |
---|
387 | (prflc: |left| = |centre|) (prfcr: |centre| = |right|) on left ≝ |
---|
388 | match left return λx. |x| = |centre| → list D with |
---|
389 | [ nil ⇒ λnil_prf. |
---|
390 | match centre return λx. |x| = |right| → list D with |
---|
391 | [ nil ⇒ λnil_nil_prf. |
---|
392 | match right return λx. |nil ?| = |x| → list D with |
---|
393 | [ nil ⇒ λnil_nil_nil_prf. nil D |
---|
394 | | cons hd tl ⇒ λcons_nil_nil_absrd. ? |
---|
395 | ] nil_nil_prf |
---|
396 | | cons hd tl ⇒ λnil_cons_absrd. ? |
---|
397 | ] prfcr |
---|
398 | | cons hd tl ⇒ λcons_prf. |
---|
399 | match centre return λx. |x| = |right| → list D with |
---|
400 | [ nil ⇒ λcons_nil_absrd. ? |
---|
401 | | cons hd' tl' ⇒ λcons_cons_prf. |
---|
402 | match right return λx. |right| = |x| → |cons ? hd' tl'| = |x| → list D with |
---|
403 | [ nil ⇒ λrefl_prf. λcons_cons_nil_absrd. ? |
---|
404 | | cons hd'' tl'' ⇒ λrefl_prf. λcons_cons_cons_prf. |
---|
405 | (f hd hd' hd'') :: (map3 A B C D f tl tl' tl'' ? ?) |
---|
406 | ] (refl ? (|right|)) cons_cons_prf |
---|
407 | ] prfcr |
---|
408 | ] prflc. |
---|
409 | [ 1: normalize in cons_nil_nil_absrd; |
---|
410 | destruct(cons_nil_nil_absrd) |
---|
411 | | 2: generalize in match nil_cons_absrd; |
---|
412 | <prfcr <nil_prf #HYP |
---|
413 | normalize in HYP; |
---|
414 | destruct(HYP) |
---|
415 | | 3: generalize in match cons_nil_absrd; |
---|
416 | <prfcr <cons_prf #HYP |
---|
417 | normalize in HYP; |
---|
418 | destruct(HYP) |
---|
419 | | 4: normalize in cons_cons_nil_absrd; |
---|
420 | destruct(cons_cons_nil_absrd) |
---|
421 | | 5: normalize in cons_cons_cons_prf; |
---|
422 | destruct(cons_cons_cons_prf) |
---|
423 | assumption |
---|
424 | | 6: generalize in match cons_cons_cons_prf; |
---|
425 | <refl_prf <prfcr <cons_prf #HYP |
---|
426 | normalize in HYP; |
---|
427 | destruct(HYP) |
---|
428 | @sym_eq assumption |
---|
429 | ] |
---|
430 | qed. |
---|
431 | |
---|
432 | lemma eq_rect_Type0_r : |
---|
433 | ∀A: Type[0]. |
---|
434 | ∀a:A. |
---|
435 | ∀P: ∀x:A. eq ? x a → Type[0]. P a (refl A a) → ∀x: A.∀p:eq ? x a. P x p. |
---|
436 | #A #a #P #H #x #p lapply H lapply P cases p // |
---|
437 | qed. |
---|
438 | |
---|
439 | let rec safe_nth (A: Type[0]) (n: nat) (l: list A) (p: n < length A l) on n: A ≝ |
---|
440 | match n return λo. o < length A l → A with |
---|
441 | [ O ⇒ |
---|
442 | match l return λm. 0 < length A m → A with |
---|
443 | [ nil ⇒ λabsd1. ? |
---|
444 | | cons hd tl ⇒ λprf1. hd |
---|
445 | ] |
---|
446 | | S n' ⇒ |
---|
447 | match l return λm. S n' < length A m → A with |
---|
448 | [ nil ⇒ λabsd2. ? |
---|
449 | | cons hd tl ⇒ λprf2. safe_nth A n' tl ? |
---|
450 | ] |
---|
451 | ] ?. |
---|
452 | [ 1: |
---|
453 | @ p |
---|
454 | | 4: |
---|
455 | normalize in prf2; |
---|
456 | normalize |
---|
457 | @ le_S_S_to_le |
---|
458 | assumption |
---|
459 | | 2: |
---|
460 | normalize in absd1; |
---|
461 | cases (not_le_Sn_O O) |
---|
462 | # H |
---|
463 | elim (H absd1) |
---|
464 | | 3: |
---|
465 | normalize in absd2; |
---|
466 | cases (not_le_Sn_O (S n')) |
---|
467 | # H |
---|
468 | elim (H absd2) |
---|
469 | ] |
---|
470 | qed. |
---|
471 | |
---|
472 | let rec nub_by_internal (A: Type[0]) (f: A → A → bool) (l: list A) (n: nat) on n ≝ |
---|
473 | match n with |
---|
474 | [ O ⇒ |
---|
475 | match l with |
---|
476 | [ nil ⇒ [ ] |
---|
477 | | cons hd tl ⇒ l |
---|
478 | ] |
---|
479 | | S n ⇒ |
---|
480 | match l with |
---|
481 | [ nil ⇒ [ ] |
---|
482 | | cons hd tl ⇒ |
---|
483 | hd :: nub_by_internal A f (filter ? (λy. notb (f y hd)) tl) n |
---|
484 | ] |
---|
485 | ]. |
---|
486 | |
---|
487 | definition nub_by ≝ |
---|
488 | λA: Type[0]. |
---|
489 | λf: A → A → bool. |
---|
490 | λl: list A. |
---|
491 | nub_by_internal A f l (length ? l). |
---|
492 | |
---|
493 | let rec member (A: Type[0]) (eq: A → A → bool) (a: A) (l: list A) on l ≝ |
---|
494 | match l with |
---|
495 | [ nil ⇒ false |
---|
496 | | cons hd tl ⇒ orb (eq a hd) (member A eq a tl) |
---|
497 | ]. |
---|
498 | |
---|
499 | let rec take (A: Type[0]) (n: nat) (l: list A) on n: list A ≝ |
---|
500 | match n with |
---|
501 | [ O ⇒ [ ] |
---|
502 | | S n ⇒ |
---|
503 | match l with |
---|
504 | [ nil ⇒ [ ] |
---|
505 | | cons hd tl ⇒ hd :: take A n tl |
---|
506 | ] |
---|
507 | ]. |
---|
508 | |
---|
509 | let rec drop (A: Type[0]) (n: nat) (l: list A) on n ≝ |
---|
510 | match n with |
---|
511 | [ O ⇒ l |
---|
512 | | S n ⇒ |
---|
513 | match l with |
---|
514 | [ nil ⇒ [ ] |
---|
515 | | cons hd tl ⇒ drop A n tl |
---|
516 | ] |
---|
517 | ]. |
---|
518 | |
---|
519 | definition list_split ≝ |
---|
520 | λA: Type[0]. |
---|
521 | λn: nat. |
---|
522 | λl: list A. |
---|
523 | 〈take A n l, drop A n l〉. |
---|
524 | |
---|
525 | let rec mapi_internal (A: Type[0]) (B: Type[0]) (n: nat) (f: nat → A → B) |
---|
526 | (l: list A) on l: list B ≝ |
---|
527 | match l with |
---|
528 | [ nil ⇒ nil ? |
---|
529 | | cons hd tl ⇒ (f n hd) :: (mapi_internal A B (n + 1) f tl) |
---|
530 | ]. |
---|
531 | |
---|
532 | definition mapi ≝ |
---|
533 | λA, B: Type[0]. |
---|
534 | λf: nat → A → B. |
---|
535 | λl: list A. |
---|
536 | mapi_internal A B 0 f l. |
---|
537 | |
---|
538 | let rec zip_pottier |
---|
539 | (A: Type[0]) (B: Type[0]) (left: list A) (right: list B) |
---|
540 | on left ≝ |
---|
541 | match left with |
---|
542 | [ nil ⇒ [ ] |
---|
543 | | cons hd tl ⇒ |
---|
544 | match right with |
---|
545 | [ nil ⇒ [ ] |
---|
546 | | cons hd' tl' ⇒ 〈hd, hd'〉 :: zip_pottier A B tl tl' |
---|
547 | ] |
---|
548 | ]. |
---|
549 | |
---|
550 | let rec zip_safe |
---|
551 | (A: Type[0]) (B: Type[0]) (left: list A) (right: list B) (prf: |left| = |right|) |
---|
552 | on left ≝ |
---|
553 | match left return λx. |x| = |right| → list (A × B) with |
---|
554 | [ nil ⇒ λnil_prf. |
---|
555 | match right return λx. |[ ]| = |x| → list (A × B) with |
---|
556 | [ nil ⇒ λnil_nil_prf. [ ] |
---|
557 | | cons hd tl ⇒ λnil_cons_absrd. ? |
---|
558 | ] nil_prf |
---|
559 | | cons hd tl ⇒ λcons_prf. |
---|
560 | match right return λx. |hd::tl| = |x| → list (A × B) with |
---|
561 | [ nil ⇒ λcons_nil_absrd. ? |
---|
562 | | cons hd' tl' ⇒ λcons_cons_prf. 〈hd, hd'〉 :: zip_safe A B tl tl' ? |
---|
563 | ] cons_prf |
---|
564 | ] prf. |
---|
565 | [ 1: normalize in nil_cons_absrd; |
---|
566 | destruct(nil_cons_absrd) |
---|
567 | | 2: normalize in cons_nil_absrd; |
---|
568 | destruct(cons_nil_absrd) |
---|
569 | | 3: normalize in cons_cons_prf; |
---|
570 | @injective_S |
---|
571 | assumption |
---|
572 | ] |
---|
573 | qed. |
---|
574 | |
---|
575 | let rec zip (A: Type[0]) (B: Type[0]) (l: list A) (r: list B) on l: option (list (A × B)) ≝ |
---|
576 | match l with |
---|
577 | [ nil ⇒ Some ? (nil (A × B)) |
---|
578 | | cons hd tl ⇒ |
---|
579 | match r with |
---|
580 | [ nil ⇒ None ? |
---|
581 | | cons hd' tl' ⇒ |
---|
582 | match zip ? ? tl tl' with |
---|
583 | [ None ⇒ None ? |
---|
584 | | Some tail ⇒ Some ? (〈hd, hd'〉 :: tail) |
---|
585 | ] |
---|
586 | ] |
---|
587 | ]. |
---|
588 | |
---|
589 | let rec foldl (A: Type[0]) (B: Type[0]) (f: A → B → A) (a: A) (l: list B) on l ≝ |
---|
590 | match l with |
---|
591 | [ nil ⇒ a |
---|
592 | | cons hd tl ⇒ foldl A B f (f a hd) tl |
---|
593 | ]. |
---|
594 | |
---|
595 | lemma foldl_step: |
---|
596 | ∀A:Type[0]. |
---|
597 | ∀B: Type[0]. |
---|
598 | ∀H: A → B → A. |
---|
599 | ∀acc: A. |
---|
600 | ∀pre: list B. |
---|
601 | ∀hd:B. |
---|
602 | foldl A B H acc (pre@[hd]) = (H (foldl A B H acc pre) hd). |
---|
603 | #A #B #H #acc #pre generalize in match acc; -acc; elim pre |
---|
604 | [ normalize; // |
---|
605 | | #hd #tl #IH #acc #X normalize; @IH ] |
---|
606 | qed. |
---|
607 | |
---|
608 | lemma foldl_append: |
---|
609 | ∀A:Type[0]. |
---|
610 | ∀B: Type[0]. |
---|
611 | ∀H: A → B → A. |
---|
612 | ∀acc: A. |
---|
613 | ∀suff,pre: list B. |
---|
614 | foldl A B H acc (pre@suff) = (foldl A B H (foldl A B H acc pre) suff). |
---|
615 | #A #B #H #acc #suff elim suff |
---|
616 | [ #pre >append_nil % |
---|
617 | | #hd #tl #IH #pre whd in ⊢ (???%); <(foldl_step … H ??) applyS (IH (pre@[hd])) ] |
---|
618 | qed. |
---|
619 | |
---|
620 | (* redirecting to library reverse *) |
---|
621 | definition rev ≝ reverse. |
---|
622 | |
---|
623 | lemma append_length: |
---|
624 | ∀A: Type[0]. |
---|
625 | ∀l, r: list A. |
---|
626 | |(l @ r)| = |l| + |r|. |
---|
627 | #A #L #R |
---|
628 | elim L |
---|
629 | [ % |
---|
630 | | #HD #TL #IH |
---|
631 | normalize >IH % |
---|
632 | ] |
---|
633 | qed. |
---|
634 | |
---|
635 | lemma append_nil: |
---|
636 | ∀A: Type[0]. |
---|
637 | ∀l: list A. |
---|
638 | l @ [ ] = l. |
---|
639 | #A #L |
---|
640 | elim L // |
---|
641 | qed. |
---|
642 | |
---|
643 | lemma rev_append: |
---|
644 | ∀A: Type[0]. |
---|
645 | ∀l, r: list A. |
---|
646 | rev A (l @ r) = rev A r @ rev A l. |
---|
647 | #A #L #R |
---|
648 | elim L |
---|
649 | [ normalize >append_nil % |
---|
650 | | #HD #TL normalize #IH |
---|
651 | >rev_append_def |
---|
652 | >rev_append_def |
---|
653 | >rev_append_def |
---|
654 | >append_nil |
---|
655 | normalize |
---|
656 | >IH |
---|
657 | @associative_append |
---|
658 | ] |
---|
659 | qed. |
---|
660 | |
---|
661 | lemma rev_length: |
---|
662 | ∀A: Type[0]. |
---|
663 | ∀l: list A. |
---|
664 | |rev A l| = |l|. |
---|
665 | #A #L |
---|
666 | elim L |
---|
667 | [ % |
---|
668 | | #HD #TL normalize #IH |
---|
669 | >rev_append_def |
---|
670 | >(append_length A (rev A TL) [HD]) |
---|
671 | normalize /2 by / |
---|
672 | ] |
---|
673 | qed. |
---|
674 | |
---|
675 | lemma nth_append_first: |
---|
676 | ∀A:Type[0]. |
---|
677 | ∀n:nat.∀l1,l2:list A.∀d:A. |
---|
678 | n < |l1| → nth n A (l1@l2) d = nth n A l1 d. |
---|
679 | #A #n #l1 #l2 #d |
---|
680 | generalize in match n; -n; elim l1 |
---|
681 | [ normalize #k #Hk @⊥ @(absurd … Hk) @not_le_Sn_O |
---|
682 | | #h #t #Hind #k normalize |
---|
683 | cases k -k |
---|
684 | [ #Hk normalize @refl |
---|
685 | | #k #Hk normalize @(Hind k) @le_S_S_to_le @Hk |
---|
686 | ] |
---|
687 | ] |
---|
688 | qed. |
---|
689 | |
---|
690 | lemma nth_append_second: |
---|
691 | ∀A: Type[0].∀n.∀l1,l2:list A.∀d.n ≥ length A l1 -> |
---|
692 | nth n A (l1@l2) d = nth (n - length A l1) A l2 d. |
---|
693 | #A #n #l1 #l2 #d |
---|
694 | generalize in match n; -n; elim l1 |
---|
695 | [ normalize #k #Hk <(minus_n_O) @refl |
---|
696 | | #h #t #Hind #k normalize |
---|
697 | cases k -k; |
---|
698 | [ #Hk @⊥ @(absurd (S (|t|) ≤ 0)) [ @Hk | @not_le_Sn_O ] |
---|
699 | | #k #Hk normalize @(Hind k) @le_S_S_to_le @Hk |
---|
700 | ] |
---|
701 | ] |
---|
702 | qed. |
---|
703 | |
---|
704 | |
---|
705 | let rec fold_left_i_aux (A: Type[0]) (B: Type[0]) |
---|
706 | (f: nat → A → B → A) (x: A) (i: nat) (l: list B) on l ≝ |
---|
707 | match l with |
---|
708 | [ nil ⇒ x |
---|
709 | | cons hd tl ⇒ fold_left_i_aux A B f (f i x hd) (S i) tl |
---|
710 | ]. |
---|
711 | |
---|
712 | definition fold_left_i ≝ λA,B,f,x. fold_left_i_aux A B f x O. |
---|
713 | |
---|
714 | notation "hvbox(t⌈o ↦ h⌉)" |
---|
715 | with precedence 45 |
---|
716 | for @{ match (? : $o=$h) with [ refl ⇒ $t ] }. |
---|
717 | |
---|
718 | definition function_apply ≝ |
---|
719 | λA, B: Type[0]. |
---|
720 | λf: A → B. |
---|
721 | λa: A. |
---|
722 | f a. |
---|
723 | |
---|
724 | notation "f break $ x" |
---|
725 | left associative with precedence 99 |
---|
726 | for @{ 'function_apply $f $x }. |
---|
727 | |
---|
728 | interpretation "Function application" 'function_apply f x = (function_apply ? ? f x). |
---|
729 | |
---|
730 | let rec iterate (A: Type[0]) (f: A → A) (a: A) (n: nat) on n ≝ |
---|
731 | match n with |
---|
732 | [ O ⇒ a |
---|
733 | | S o ⇒ f (iterate A f a o) |
---|
734 | ]. |
---|
735 | |
---|
736 | let rec division_aux (m: nat) (n : nat) (p: nat) ≝ |
---|
737 | match ltb n (S p) with |
---|
738 | [ true ⇒ O |
---|
739 | | false ⇒ |
---|
740 | match m with |
---|
741 | [ O ⇒ O |
---|
742 | | (S q) ⇒ S (division_aux q (n - (S p)) p) |
---|
743 | ] |
---|
744 | ]. |
---|
745 | |
---|
746 | definition division ≝ |
---|
747 | λm, n: nat. |
---|
748 | match n with |
---|
749 | [ O ⇒ S m |
---|
750 | | S o ⇒ division_aux m m o |
---|
751 | ]. |
---|
752 | |
---|
753 | notation "hvbox(n break ÷ m)" |
---|
754 | right associative with precedence 47 |
---|
755 | for @{ 'division $n $m }. |
---|
756 | |
---|
757 | interpretation "Nat division" 'division n m = (division n m). |
---|
758 | |
---|
759 | let rec modulus_aux (m: nat) (n: nat) (p: nat) ≝ |
---|
760 | match leb n p with |
---|
761 | [ true ⇒ n |
---|
762 | | false ⇒ |
---|
763 | match m with |
---|
764 | [ O ⇒ n |
---|
765 | | S o ⇒ modulus_aux o (n - (S p)) p |
---|
766 | ] |
---|
767 | ]. |
---|
768 | |
---|
769 | definition modulus ≝ |
---|
770 | λm, n: nat. |
---|
771 | match n with |
---|
772 | [ O ⇒ m |
---|
773 | | S o ⇒ modulus_aux m m o |
---|
774 | ]. |
---|
775 | |
---|
776 | notation "hvbox(n break 'mod' m)" |
---|
777 | right associative with precedence 47 |
---|
778 | for @{ 'modulus $n $m }. |
---|
779 | |
---|
780 | interpretation "Nat modulus" 'modulus m n = (modulus m n). |
---|
781 | |
---|
782 | definition divide_with_remainder ≝ |
---|
783 | λm, n: nat. |
---|
784 | mk_Prod … (m ÷ n) (modulus m n). |
---|
785 | |
---|
786 | let rec exponential (m: nat) (n: nat) on n ≝ |
---|
787 | match n with |
---|
788 | [ O ⇒ S O |
---|
789 | | S o ⇒ m * exponential m o |
---|
790 | ]. |
---|
791 | |
---|
792 | interpretation "Nat exponential" 'exp n m = (exponential n m). |
---|
793 | |
---|
794 | notation "hvbox(a break ⊎ b)" |
---|
795 | left associative with precedence 55 |
---|
796 | for @{ 'disjoint_union $a $b }. |
---|
797 | interpretation "sum" 'disjoint_union A B = (Sum A B). |
---|
798 | |
---|
799 | theorem less_than_or_equal_monotone: |
---|
800 | ∀m, n: nat. |
---|
801 | m ≤ n → (S m) ≤ (S n). |
---|
802 | #m #n #H |
---|
803 | elim H |
---|
804 | /2 by le_n, le_S/ |
---|
805 | qed. |
---|
806 | |
---|
807 | theorem less_than_or_equal_b_complete: |
---|
808 | ∀m, n: nat. |
---|
809 | leb m n = false → ¬(m ≤ n). |
---|
810 | #m; |
---|
811 | elim m; |
---|
812 | normalize |
---|
813 | [ #n #H |
---|
814 | destruct |
---|
815 | | #y #H1 #z |
---|
816 | cases z |
---|
817 | normalize |
---|
818 | [ #H |
---|
819 | /2 by / |
---|
820 | | /3 by not_le_to_not_le_S_S/ |
---|
821 | ] |
---|
822 | ] |
---|
823 | qed. |
---|
824 | |
---|
825 | theorem less_than_or_equal_b_correct: |
---|
826 | ∀m, n: nat. |
---|
827 | leb m n = true → m ≤ n. |
---|
828 | #m |
---|
829 | elim m |
---|
830 | // |
---|
831 | #y #H1 #z |
---|
832 | cases z |
---|
833 | normalize |
---|
834 | [ #H |
---|
835 | destruct |
---|
836 | | #n #H lapply (H1 … H) /2 by le_S_S/ |
---|
837 | ] |
---|
838 | qed. |
---|
839 | |
---|
840 | definition less_than_or_equal_b_elim: |
---|
841 | ∀m, n: nat. |
---|
842 | ∀P: bool → Type[0]. |
---|
843 | (m ≤ n → P true) → (¬(m ≤ n) → P false) → P (leb m n). |
---|
844 | #m #n #P #H1 #H2; |
---|
845 | lapply (less_than_or_equal_b_correct m n) |
---|
846 | lapply (less_than_or_equal_b_complete m n) |
---|
847 | cases (leb m n) |
---|
848 | /3 by / |
---|
849 | qed. |
---|
850 | |
---|
851 | lemma lt_m_n_to_exists_o_plus_m_n: |
---|
852 | ∀m, n: nat. |
---|
853 | m < n → ∃o: nat. m + o = n. |
---|
854 | #m #n |
---|
855 | cases m |
---|
856 | [1: |
---|
857 | #irrelevant |
---|
858 | %{n} % |
---|
859 | |2: |
---|
860 | #m' #lt_hyp |
---|
861 | %{(n - S m')} |
---|
862 | >commutative_plus in ⊢ (??%?); |
---|
863 | <plus_minus_m_m |
---|
864 | [1: |
---|
865 | % |
---|
866 | |2: |
---|
867 | @lt_S_to_lt |
---|
868 | assumption |
---|
869 | ] |
---|
870 | ] |
---|
871 | qed. |
---|
872 | |
---|
873 | lemma lt_O_n_to_S_pred_n_n: |
---|
874 | ∀n: nat. |
---|
875 | 0 < n → S (pred n) = n. |
---|
876 | #n |
---|
877 | cases n |
---|
878 | [1: |
---|
879 | #absurd |
---|
880 | cases(lt_to_not_zero 0 0 absurd) |
---|
881 | |2: |
---|
882 | #n' #lt_hyp % |
---|
883 | ] |
---|
884 | qed. |
---|
885 | |
---|
886 | lemma exists_plus_m_n_to_exists_Sn: |
---|
887 | ∀m, n: nat. |
---|
888 | m < n → ∃p: nat. S p = n. |
---|
889 | #m #n |
---|
890 | cases m |
---|
891 | [1: |
---|
892 | #lt_hyp %{(pred n)} |
---|
893 | @(lt_O_n_to_S_pred_n_n … lt_hyp) |
---|
894 | |2: |
---|
895 | #m' #lt_hyp %{(pred n)} |
---|
896 | @(lt_O_n_to_S_pred_n_n) |
---|
897 | @(transitive_le … (S m') …) |
---|
898 | [1: |
---|
899 | // |
---|
900 | |2: |
---|
901 | @lt_S_to_lt |
---|
902 | assumption |
---|
903 | ] |
---|
904 | ] |
---|
905 | qed. |
---|
906 | |
---|
907 | lemma plus_right_monotone: |
---|
908 | ∀m, n, o: nat. |
---|
909 | m = n → m + o = n + o. |
---|
910 | #m #n #o #refl >refl % |
---|
911 | qed. |
---|
912 | |
---|
913 | lemma plus_left_monotone: |
---|
914 | ∀m, n, o: nat. |
---|
915 | m = n → o + m = o + n. |
---|
916 | #m #n #o #refl destruct % |
---|
917 | qed. |
---|
918 | |
---|
919 | lemma minus_plus_cancel: |
---|
920 | ∀m, n : nat. |
---|
921 | ∀proof: n ≤ m. |
---|
922 | (m - n) + n = m. |
---|
923 | #m #n #proof /2 by plus_minus/ |
---|
924 | qed. |
---|
925 | |
---|
926 | lemma lt_to_le_to_le: |
---|
927 | ∀n, m, p: nat. |
---|
928 | n < m → m ≤ p → n ≤ p. |
---|
929 | #n #m #p #H #H1 |
---|
930 | elim H |
---|
931 | [1: |
---|
932 | @(transitive_le n m p) /2/ |
---|
933 | |2: |
---|
934 | /2/ |
---|
935 | ] |
---|
936 | qed. |
---|
937 | |
---|
938 | lemma eqb_decidable: |
---|
939 | ∀l, r: nat. |
---|
940 | (eqb l r = true) ∨ (eqb l r = false). |
---|
941 | #l #r // |
---|
942 | qed. |
---|
943 | |
---|
944 | lemma r_Sr_and_l_r_to_Sl_r: |
---|
945 | ∀r, l: nat. |
---|
946 | (∃r': nat. r = S r' ∧ l = r') → S l = r. |
---|
947 | #r #l #exists_hyp |
---|
948 | cases exists_hyp #r' |
---|
949 | #and_hyp cases and_hyp |
---|
950 | #left_hyp #right_hyp |
---|
951 | destruct % |
---|
952 | qed. |
---|
953 | |
---|
954 | lemma eqb_Sn_to_exists_n': |
---|
955 | ∀m, n: nat. |
---|
956 | eqb (S m) n = true → ∃n': nat. n = S n'. |
---|
957 | #m #n |
---|
958 | cases n |
---|
959 | [1: |
---|
960 | normalize #absurd |
---|
961 | destruct(absurd) |
---|
962 | |2: |
---|
963 | #n' #_ %{n'} % |
---|
964 | ] |
---|
965 | qed. |
---|
966 | |
---|
967 | lemma eqb_true_to_eqb_S_S_true: |
---|
968 | ∀m, n: nat. |
---|
969 | eqb m n = true → eqb (S m) (S n) = true. |
---|
970 | #m #n normalize #assm assumption |
---|
971 | qed. |
---|
972 | |
---|
973 | lemma eqb_S_S_true_to_eqb_true: |
---|
974 | ∀m, n: nat. |
---|
975 | eqb (S m) (S n) = true → eqb m n = true. |
---|
976 | #m #n normalize #assm assumption |
---|
977 | qed. |
---|
978 | |
---|
979 | lemma eqb_true_to_refl: |
---|
980 | ∀l, r: nat. |
---|
981 | eqb l r = true → l = r. |
---|
982 | #l |
---|
983 | elim l |
---|
984 | [1: |
---|
985 | #r cases r |
---|
986 | [1: |
---|
987 | #_ % |
---|
988 | |2: |
---|
989 | #l' normalize |
---|
990 | #absurd destruct(absurd) |
---|
991 | ] |
---|
992 | |2: |
---|
993 | #l' #inductive_hypothesis #r |
---|
994 | #eqb_refl @r_Sr_and_l_r_to_Sl_r |
---|
995 | %{(pred r)} @conj |
---|
996 | [1: |
---|
997 | cases (eqb_Sn_to_exists_n' … eqb_refl) |
---|
998 | #r' #S_assm >S_assm % |
---|
999 | |2: |
---|
1000 | cases (eqb_Sn_to_exists_n' … eqb_refl) |
---|
1001 | #r' #refl_assm destruct normalize |
---|
1002 | @inductive_hypothesis |
---|
1003 | normalize in eqb_refl; assumption |
---|
1004 | ] |
---|
1005 | ] |
---|
1006 | qed. |
---|
1007 | |
---|
1008 | lemma r_O_or_exists_r_r_Sr_and_l_neq_r_to_Sl_neq_r: |
---|
1009 | ∀r, l: nat. |
---|
1010 | r = O ∨ (∃r': nat. r = S r' ∧ l ≠ r') → S l ≠ r. |
---|
1011 | #r #l #disj_hyp |
---|
1012 | cases disj_hyp |
---|
1013 | [1: |
---|
1014 | #r_O_refl destruct @nmk |
---|
1015 | #absurd destruct(absurd) |
---|
1016 | |2: |
---|
1017 | #exists_hyp cases exists_hyp #r' |
---|
1018 | #conj_hyp cases conj_hyp #left_conj #right_conj |
---|
1019 | destruct @nmk #S_S_refl_hyp |
---|
1020 | elim right_conj #hyp @hyp // |
---|
1021 | ] |
---|
1022 | qed. |
---|
1023 | |
---|
1024 | lemma neq_l_r_to_neq_Sl_Sr: |
---|
1025 | ∀l, r: nat. |
---|
1026 | l ≠ r → S l ≠ S r. |
---|
1027 | #l #r #l_neq_r_assm |
---|
1028 | @nmk #Sl_Sr_assm cases l_neq_r_assm |
---|
1029 | #assm @assm // |
---|
1030 | qed. |
---|
1031 | |
---|
1032 | lemma eqb_false_to_not_refl: |
---|
1033 | ∀l, r: nat. |
---|
1034 | eqb l r = false → l ≠ r. |
---|
1035 | #l |
---|
1036 | elim l |
---|
1037 | [1: |
---|
1038 | #r cases r |
---|
1039 | [1: |
---|
1040 | normalize #absurd destruct(absurd) |
---|
1041 | |2: |
---|
1042 | #r' #_ @nmk |
---|
1043 | #absurd destruct(absurd) |
---|
1044 | ] |
---|
1045 | |2: |
---|
1046 | #l' #inductive_hypothesis #r |
---|
1047 | cases r |
---|
1048 | [1: |
---|
1049 | #eqb_false_assm |
---|
1050 | @r_O_or_exists_r_r_Sr_and_l_neq_r_to_Sl_neq_r |
---|
1051 | @or_introl % |
---|
1052 | |2: |
---|
1053 | #r' #eqb_false_assm |
---|
1054 | @neq_l_r_to_neq_Sl_Sr |
---|
1055 | @inductive_hypothesis |
---|
1056 | assumption |
---|
1057 | ] |
---|
1058 | ] |
---|
1059 | qed. |
---|
1060 | |
---|
1061 | lemma le_to_lt_or_eq: |
---|
1062 | ∀m, n: nat. |
---|
1063 | m ≤ n → m = n ∨ m < n. |
---|
1064 | #m #n #le_hyp |
---|
1065 | cases le_hyp |
---|
1066 | [1: |
---|
1067 | @or_introl % |
---|
1068 | |2: |
---|
1069 | #m' #le_hyp' |
---|
1070 | @or_intror |
---|
1071 | normalize |
---|
1072 | @le_S_S assumption |
---|
1073 | ] |
---|
1074 | qed. |
---|
1075 | |
---|
1076 | lemma le_neq_to_lt: |
---|
1077 | ∀m, n: nat. |
---|
1078 | m ≤ n → m ≠ n → m < n. |
---|
1079 | #m #n #le_hyp #neq_hyp |
---|
1080 | cases neq_hyp |
---|
1081 | #eq_absurd_hyp |
---|
1082 | generalize in match (le_to_lt_or_eq m n le_hyp); |
---|
1083 | #disj_assm cases disj_assm |
---|
1084 | [1: |
---|
1085 | #absurd cases (eq_absurd_hyp absurd) |
---|
1086 | |2: |
---|
1087 | #assm assumption |
---|
1088 | ] |
---|
1089 | qed. |
---|
1090 | |
---|
1091 | inverter nat_jmdiscr for nat. |
---|
1092 | |
---|
1093 | lemma plus_lt_to_lt: |
---|
1094 | ∀m, n, o: nat. |
---|
1095 | m + n < o → m < o. |
---|
1096 | #m #n #o |
---|
1097 | elim n |
---|
1098 | [1: |
---|
1099 | <(plus_n_O m) in ⊢ (% → ?); |
---|
1100 | #assumption assumption |
---|
1101 | |2: |
---|
1102 | #n' #inductive_hypothesis |
---|
1103 | <(plus_n_Sm m n') in ⊢ (% → ?); |
---|
1104 | #assm @inductive_hypothesis |
---|
1105 | normalize in assm; normalize |
---|
1106 | /2 by lt_S_to_lt/ |
---|
1107 | ] |
---|
1108 | qed. |
---|
1109 | |
---|
1110 | include "arithmetics/div_and_mod.ma". |
---|
1111 | |
---|
1112 | lemma n_plus_1_n_to_False: |
---|
1113 | ∀n: nat. |
---|
1114 | n + 1 = n → False. |
---|
1115 | #n elim n |
---|
1116 | [1: |
---|
1117 | normalize #absurd destruct(absurd) |
---|
1118 | |2: |
---|
1119 | #n' #inductive_hypothesis normalize |
---|
1120 | #absurd @inductive_hypothesis /2 by injective_S/ |
---|
1121 | ] |
---|
1122 | qed. |
---|
1123 | |
---|
1124 | lemma one_two_times_n_to_False: |
---|
1125 | ∀n: nat. |
---|
1126 | 1=2*n→False. |
---|
1127 | #n cases n |
---|
1128 | [1: |
---|
1129 | normalize #absurd destruct(absurd) |
---|
1130 | |2: |
---|
1131 | #n' normalize #absurd |
---|
1132 | lapply (injective_S … absurd) -absurd #absurd |
---|
1133 | /2/ |
---|
1134 | ] |
---|
1135 | qed. |
---|
1136 | |
---|
1137 | let rec odd_p |
---|
1138 | (n: nat) |
---|
1139 | on n ≝ |
---|
1140 | match n with |
---|
1141 | [ O ⇒ False |
---|
1142 | | S n' ⇒ even_p n' |
---|
1143 | ] |
---|
1144 | and even_p |
---|
1145 | (n: nat) |
---|
1146 | on n ≝ |
---|
1147 | match n with |
---|
1148 | [ O ⇒ True |
---|
1149 | | S n' ⇒ odd_p n' |
---|
1150 | ]. |
---|
1151 | |
---|
1152 | let rec n_even_p_to_n_plus_2_even_p |
---|
1153 | (n: nat) |
---|
1154 | on n: even_p n → even_p (n + 2) ≝ |
---|
1155 | match n with |
---|
1156 | [ O ⇒ ? |
---|
1157 | | S n' ⇒ ? |
---|
1158 | ] |
---|
1159 | and n_odd_p_to_n_plus_2_odd_p |
---|
1160 | (n: nat) |
---|
1161 | on n: odd_p n → odd_p (n + 2) ≝ |
---|
1162 | match n with |
---|
1163 | [ O ⇒ ? |
---|
1164 | | S n' ⇒ ? |
---|
1165 | ]. |
---|
1166 | [1,3: |
---|
1167 | normalize #assm assumption |
---|
1168 | |2: |
---|
1169 | normalize @n_odd_p_to_n_plus_2_odd_p |
---|
1170 | |4: |
---|
1171 | normalize @n_even_p_to_n_plus_2_even_p |
---|
1172 | ] |
---|
1173 | qed. |
---|
1174 | |
---|
1175 | let rec two_times_n_even_p |
---|
1176 | (n: nat) |
---|
1177 | on n: even_p (2 * n) ≝ |
---|
1178 | match n with |
---|
1179 | [ O ⇒ ? |
---|
1180 | | S n' ⇒ ? |
---|
1181 | ] |
---|
1182 | and two_times_n_plus_one_odd_p |
---|
1183 | (n: nat) |
---|
1184 | on n: odd_p ((2 * n) + 1) ≝ |
---|
1185 | match n with |
---|
1186 | [ O ⇒ ? |
---|
1187 | | S n' ⇒ ? |
---|
1188 | ]. |
---|
1189 | [1,3: |
---|
1190 | normalize @I |
---|
1191 | |2: |
---|
1192 | normalize |
---|
1193 | >plus_n_Sm |
---|
1194 | <(associative_plus n' n' 1) |
---|
1195 | >(plus_n_O (n' + n')) |
---|
1196 | cut(n' + n' + 0 + 1 = 2 * n' + 1) |
---|
1197 | [1: |
---|
1198 | // |
---|
1199 | |2: |
---|
1200 | #refl_assm >refl_assm |
---|
1201 | @two_times_n_plus_one_odd_p |
---|
1202 | ] |
---|
1203 | |4: |
---|
1204 | normalize |
---|
1205 | >plus_n_Sm |
---|
1206 | cut(n' + (n' + 1) + 1 = (2 * n') + 2) |
---|
1207 | [1: |
---|
1208 | normalize /2/ |
---|
1209 | |2: |
---|
1210 | #refl_assm >refl_assm |
---|
1211 | @n_even_p_to_n_plus_2_even_p |
---|
1212 | @two_times_n_even_p |
---|
1213 | ] |
---|
1214 | ] |
---|
1215 | qed. |
---|
1216 | |
---|
1217 | include alias "basics/logic.ma". |
---|
1218 | |
---|
1219 | let rec even_p_to_not_odd_p |
---|
1220 | (n: nat) |
---|
1221 | on n: even_p n → ¬ odd_p n ≝ |
---|
1222 | match n with |
---|
1223 | [ O ⇒ ? |
---|
1224 | | S n' ⇒ ? |
---|
1225 | ] |
---|
1226 | and odd_p_to_not_even_p |
---|
1227 | (n: nat) |
---|
1228 | on n: odd_p n → ¬ even_p n ≝ |
---|
1229 | match n with |
---|
1230 | [ O ⇒ ? |
---|
1231 | | S n' ⇒ ? |
---|
1232 | ]. |
---|
1233 | [1: |
---|
1234 | normalize #_ |
---|
1235 | @nmk #assm assumption |
---|
1236 | |3: |
---|
1237 | normalize #absurd |
---|
1238 | cases absurd |
---|
1239 | |2: |
---|
1240 | normalize |
---|
1241 | @odd_p_to_not_even_p |
---|
1242 | |4: |
---|
1243 | normalize |
---|
1244 | @even_p_to_not_odd_p |
---|
1245 | ] |
---|
1246 | qed. |
---|
1247 | |
---|
1248 | lemma even_p_odd_p_cases: |
---|
1249 | ∀n: nat. |
---|
1250 | even_p n ∨ odd_p n. |
---|
1251 | #n elim n |
---|
1252 | [1: |
---|
1253 | normalize @or_introl @I |
---|
1254 | |2: |
---|
1255 | #n' #inductive_hypothesis |
---|
1256 | normalize |
---|
1257 | cases inductive_hypothesis |
---|
1258 | #assm |
---|
1259 | try (@or_introl assumption) |
---|
1260 | try (@or_intror assumption) |
---|
1261 | ] |
---|
1262 | qed. |
---|
1263 | |
---|
1264 | lemma two_times_n_plus_one_refl_two_times_n_to_False: |
---|
1265 | ∀m, n: nat. |
---|
1266 | 2 * m + 1 = 2 * n → False. |
---|
1267 | #m #n |
---|
1268 | #assm |
---|
1269 | cut (even_p (2 * n) ∧ even_p ((2 * m) + 1)) |
---|
1270 | [1: |
---|
1271 | >assm |
---|
1272 | @conj |
---|
1273 | @two_times_n_even_p |
---|
1274 | |2: |
---|
1275 | * #_ #absurd |
---|
1276 | cases (even_p_to_not_odd_p … absurd) |
---|
1277 | #assm @assm |
---|
1278 | @two_times_n_plus_one_odd_p |
---|
1279 | ] |
---|
1280 | qed. |
---|
1281 | |
---|
1282 | lemma not_Some_neq_None_to_False: |
---|
1283 | ∀a: Type[0]. |
---|
1284 | ∀e: a. |
---|
1285 | ¬ (Some a e ≠ None a) → False. |
---|
1286 | #a #e #absurd cases absurd -absurd |
---|
1287 | #absurd @absurd @nmk -absurd |
---|
1288 | #absurd destruct(absurd) |
---|
1289 | qed. |
---|
1290 | |
---|
1291 | lemma not_None_to_Some: |
---|
1292 | ∀A: Type[0]. |
---|
1293 | ∀o: option A. |
---|
1294 | o ≠ None A → ∃v: A. o = Some A v. |
---|
1295 | #A #o cases o |
---|
1296 | [1: |
---|
1297 | #absurd cases absurd #absurd' cases (absurd' (refl …)) |
---|
1298 | |2: |
---|
1299 | #v' #ignore /2/ |
---|
1300 | ] |
---|
1301 | qed. |
---|
1302 | |
---|
1303 | lemma inclusive_disjunction_true: |
---|
1304 | ∀b, c: bool. |
---|
1305 | (orb b c) = true → b = true ∨ c = true. |
---|
1306 | # b |
---|
1307 | # c |
---|
1308 | elim b |
---|
1309 | [ normalize |
---|
1310 | # H |
---|
1311 | @ or_introl |
---|
1312 | % |
---|
1313 | | normalize |
---|
1314 | /3 by trans_eq, orb_true_l/ |
---|
1315 | ] |
---|
1316 | qed. |
---|
1317 | |
---|
1318 | lemma conjunction_true: |
---|
1319 | ∀b, c: bool. |
---|
1320 | andb b c = true → b = true ∧ c = true. |
---|
1321 | # b |
---|
1322 | # c |
---|
1323 | elim b |
---|
1324 | normalize |
---|
1325 | [ /2 by conj/ |
---|
1326 | | # K |
---|
1327 | destruct |
---|
1328 | ] |
---|
1329 | qed. |
---|
1330 | |
---|
1331 | lemma eq_true_false: false=true → False. |
---|
1332 | # K |
---|
1333 | destruct |
---|
1334 | qed. |
---|
1335 | |
---|
1336 | lemma inclusive_disjunction_b_true: ∀b. orb b true = true. |
---|
1337 | # b |
---|
1338 | cases b |
---|
1339 | % |
---|
1340 | qed. |
---|
1341 | |
---|
1342 | (* XXX: to be moved into logic/basics.ma *) |
---|
1343 | lemma and_intro_right: |
---|
1344 | ∀a, b: Prop. |
---|
1345 | a → (a → b) → a ∧ b. |
---|
1346 | #a #b /3/ |
---|
1347 | qed. |
---|
1348 | |
---|
1349 | definition bool_to_Prop ≝ |
---|
1350 | λb. match b with [ true ⇒ True | false ⇒ False ]. |
---|
1351 | |
---|
1352 | coercion bool_to_Prop: ∀b:bool. Prop ≝ bool_to_Prop on _b:bool to Type[0]. |
---|
1353 | |
---|
1354 | lemma bool_as_Prop_to_eq : ∀b : bool. b → b = true. |
---|
1355 | **% |
---|
1356 | qed. |
---|
1357 | |
---|
1358 | (* with this you can use prf : b with b : bool with rewriting |
---|
1359 | >prf rewrites b as true *) |
---|
1360 | coercion bool_to_Prop_to_eq : ∀b : bool.∀prf : b.b = true |
---|
1361 | ≝ bool_as_Prop_to_eq on _prf : bool_to_Prop ? to (? = true). |
---|
1362 | |
---|
1363 | lemma andb_Prop : ∀b,d : bool.b → d → b∧d. |
---|
1364 | #b #d #btrue #dtrue >btrue >dtrue % |
---|
1365 | qed. |
---|
1366 | |
---|
1367 | lemma andb_Prop_true : ∀b,d : bool. (b∧d) → And (bool_to_Prop b) (bool_to_Prop d). |
---|
1368 | #b #d #bdtrue elim (andb_true … bdtrue) #btrue #dtrue >btrue >dtrue % % |
---|
1369 | qed. |
---|
1370 | |
---|
1371 | lemma orb_Prop_l : ∀b,d : bool.b → b∨d. |
---|
1372 | #b #d #btrue >btrue % |
---|
1373 | qed. |
---|
1374 | |
---|
1375 | lemma orb_Prop_r : ∀b,d : bool.d → b∨d. |
---|
1376 | #b #d #dtrue >dtrue elim b % |
---|
1377 | qed. |
---|
1378 | |
---|
1379 | lemma orb_Prop_true : ∀b,d : bool. (b∨d) → Or (bool_to_Prop b) (bool_to_Prop d). |
---|
1380 | #b #d #bdtrue elim (orb_true_l … bdtrue) #xtrue >xtrue [%1 | %2] % |
---|
1381 | qed. |
---|
1382 | |
---|
1383 | lemma notb_Prop : ∀b : bool. Not (bool_to_Prop b) → notb b. |
---|
1384 | * * #H [@H % | %] |
---|
1385 | qed. |
---|
1386 | |
---|
1387 | lemma eq_false_to_notb: ∀b. b = false → ¬ b. |
---|
1388 | *; /2 by eq_true_false, I/ |
---|
1389 | qed. |
---|
1390 | |
---|
1391 | lemma not_b_to_eq_false : ∀b : bool. Not (bool_to_Prop b) → b = false. |
---|
1392 | ** #H [elim (H ?) % | %] |
---|
1393 | qed. |
---|
1394 | |
---|
1395 | (* with this you can use prf : ¬b with b : bool with rewriting |
---|
1396 | >prf rewrites b as false *) |
---|
1397 | coercion not_bool_to_Prop_to_eq : ∀b : bool.∀prf : Not (bool_to_Prop b).b = false |
---|
1398 | ≝ not_b_to_eq_false on _prf : Not (bool_to_Prop ?) to (? = false). |
---|
1399 | |
---|
1400 | |
---|
1401 | lemma true_or_false_Prop : ∀b : bool.Or (bool_to_Prop b) (¬(bool_to_Prop b)). |
---|
1402 | * [%1 % | %2 % *] |
---|
1403 | qed. |
---|
1404 | |
---|
1405 | lemma eq_true_to_b : ∀b. b = true → b. |
---|
1406 | #b #btrue >btrue % |
---|
1407 | qed. |
---|
1408 | |
---|
1409 | definition if_then_else_safe : ∀A : Type[0].∀b : bool.(b → A) → (¬(bool_to_Prop b) → A) → A ≝ |
---|
1410 | λA,b,f,g. |
---|
1411 | match b return λx.match x with [true ⇒ bool_to_Prop b | false ⇒ ¬bool_to_Prop b] → A with |
---|
1412 | [ true ⇒ f |
---|
1413 | | false ⇒ g |
---|
1414 | ] ?. elim b % * |
---|
1415 | qed. |
---|
1416 | |
---|
1417 | notation > "'If' b 'then' 'with' ident prf1 'do' f 'else' 'with' ident prf2 'do' g" with precedence 46 for |
---|
1418 | @{'if_then_else_safe $b (λ${ident prf1}.$f) (λ${ident prf2}.$g)}. |
---|
1419 | notation > "'If' b 'then' 'with' ident prf1 : ty1 'do' f 'else' 'with' ident prf2 : ty2 'do' g" with precedence 46 for |
---|
1420 | @{'if_then_else_safe $b (λ${ident prf1}:$ty1.$f) (λ${ident prf2}:$ty2.$g)}. |
---|
1421 | notation > "'If' b 'then' f 'else' 'with' ident prf2 'do' g" with precedence 46 for |
---|
1422 | @{'if_then_else_safe $b (λ_.$f) (λ${ident prf2}.$g)}. |
---|
1423 | notation > "'If' b 'then' f 'else' 'with' ident prf2 : ty2 'do' g" with precedence 46 for |
---|
1424 | @{'if_then_else_safe $b (λ_.$f) (λ${ident prf2}:$ty2.$g)}. |
---|
1425 | notation > "'If' b 'then' 'with' ident prf1 'do' f 'else' g" with precedence 46 for |
---|
1426 | @{'if_then_else_safe $b (λ${ident prf1}.$f) (λ_.$g)}. |
---|
1427 | notation > "'If' b 'then' 'with' ident prf1 : ty1 'do' f 'else' g" with precedence 46 for |
---|
1428 | @{'if_then_else_safe $b (λ${ident prf1}:$ty1.$f) (λ_.$g)}. |
---|
1429 | |
---|
1430 | notation < "hvbox('If' \nbsp b \nbsp 'then' \nbsp break 'with' \nbsp ident prf1 : ty1 \nbsp 'do' \nbsp break f \nbsp break 'else' \nbsp break 'with' \nbsp ident prf2 : ty2 \nbsp 'do' \nbsp break g)" with precedence 46 for |
---|
1431 | @{'if_then_else_safe $b (λ${ident prf1}:$ty1.$f) (λ${ident prf2}:$ty2.$g)}. |
---|
1432 | notation < "hvbox('If' \nbsp b \nbsp 'then' \nbsp break f \nbsp break 'else' \nbsp break 'with' \nbsp ident prf2 : ty2 \nbsp 'do' \nbsp break g)" with precedence 46 for |
---|
1433 | @{'if_then_else_safe $b (λ_:$ty1.$f) (λ${ident prf2}:$ty2.$g)}. |
---|
1434 | notation < "hvbox('If' \nbsp b \nbsp 'then' \nbsp break 'with' \nbsp ident prf1 : ty1 \nbsp 'do' \nbsp break f \nbsp break 'else' \nbsp break g)" with precedence 46 for |
---|
1435 | @{'if_then_else_safe $b (λ${ident prf1}:$ty1.$f) (λ_:$ty2.$g)}. |
---|
1436 | |
---|
1437 | interpretation "dependent if then else" 'if_then_else_safe b f g = (if_then_else_safe ? b f g). |
---|
1438 | |
---|
1439 | (* Also extracts an equality proof (useful when not using Russell). *) |
---|
1440 | notation > "hvbox('let' 〈ident x,ident y〉 'as' ident E 'return' ty ≝ t 'in' s)" |
---|
1441 | with precedence 10 |
---|
1442 | for @{ match $t return λx.∀${ident E}: x = $t. $ty with [ mk_Prod ${ident x} ${ident y} ⇒ |
---|
1443 | λ${ident E}.$s ] (refl ? $t) }. |
---|
1444 | |
---|
1445 | notation > "hvbox('deplet' 〈ident x,ident y〉 'as' ident E ≝ t 'in' s)" |
---|
1446 | with precedence 10 |
---|
1447 | for @{ match $t return λx.∀${ident E}: x = $t. Σz: ?. ? with [ mk_Prod ${ident x} ${ident y} ⇒ |
---|
1448 | λ${ident E}.$s ] (refl ? $t) }. |
---|
1449 | |
---|
1450 | notation > "hvbox('deplet' 〈ident x,ident y,ident z〉 'as' ident E ≝ t 'in' s)" |
---|
1451 | with precedence 10 |
---|
1452 | for @{ match $t return λx.∀${fresh w}:x = $t. Σq: ?. ? with [ mk_Prod ${fresh xy} ${ident z} ⇒ |
---|
1453 | match ${fresh xy} return λx.∀${ident E}:? = $t. Σu: ?. ? with [ mk_Prod ${ident x} ${ident y} ⇒ |
---|
1454 | λ${ident E}.$s ] ] (refl ? $t) }. |
---|
1455 | |
---|
1456 | notation > "hvbox('let' 〈ident x,ident y,ident z〉 'as' ident E 'return' ty ≝ t 'in' s)" |
---|
1457 | with precedence 10 |
---|
1458 | for @{ match $t return λx.∀${fresh w}:x = $t. Σq: ?. ? with [ mk_Prod ${fresh xy} ${ident z} ⇒ |
---|
1459 | match ${fresh xy} return λx.∀${ident E}:? = $t. $ty with [ mk_Prod ${ident x} ${ident y} ⇒ |
---|
1460 | λ${ident E}.$s ] ] (refl ? $t) }. |
---|
1461 | |
---|
1462 | lemma length_append: |
---|
1463 | ∀A.∀l1,l2:list A. |
---|
1464 | |l1 @ l2| = |l1| + |l2|. |
---|
1465 | #A #l1 elim l1 |
---|
1466 | [ // |
---|
1467 | | #hd #tl #IH #l2 normalize <IH //] |
---|
1468 | qed. |
---|
1469 | |
---|
1470 | lemma nth_cons: |
---|
1471 | ∀n,A,h,t,y. |
---|
1472 | nth (S n) A (h::t) y = nth n A t y. |
---|
1473 | #n #A #h #t #y /2 by refl/ |
---|
1474 | qed. |
---|
1475 | |
---|
1476 | lemma option_destruct_Some: ∀A,a,b. Some A a = Some A b → a=b. |
---|
1477 | #A #a #b #EQ destruct // |
---|
1478 | qed. |
---|
1479 | |
---|
1480 | lemma pi1_eq: ∀A:Type[0].∀P:A->Prop.∀s1:Σa1:A.P a1.∀s2:Σa2:A.P a2. |
---|
1481 | s1 = s2 → (pi1 ?? s1) = (pi1 ?? s2). |
---|
1482 | #A #P #s1 #s2 / by / |
---|
1483 | qed. |
---|
1484 | |
---|
1485 | lemma Some_eq: |
---|
1486 | ∀T:Type[0].∀x,y:T. Some T x = Some T y → x = y. |
---|
1487 | #T #x #y #H @option_destruct_Some @H |
---|
1488 | qed. |
---|
1489 | |
---|
1490 | lemma not_neq_None_to_eq : ∀A.∀a : option A.¬a≠None ? → a = None ?. |
---|
1491 | #A * [2: #a] * // #ABS elim (ABS ?) % #ABS' destruct(ABS') |
---|
1492 | qed. |
---|
1493 | |
---|
1494 | coercion not_neq_None : ∀A.∀a : option A.∀prf : ¬a≠None ?.a = None ? ≝ |
---|
1495 | not_neq_None_to_eq on _prf : ¬?≠None ? to ? = None ?. |
---|
1496 | |
---|
1497 | lemma geb_to_leb: ∀a,b:ℕ.geb a b = leb b a. |
---|
1498 | #a #b / by refl/ |
---|
1499 | qed. |
---|
1500 | |
---|
1501 | lemma nth_last: ∀A,a,l. |
---|
1502 | nth (|l|) A l a = a. |
---|
1503 | #A #a #l elim l |
---|
1504 | [ / by / |
---|
1505 | | #h #t #Hind whd in match (nth ????); whd in match (tail ??); @Hind |
---|
1506 | ] |
---|
1507 | qed. |
---|
1508 | |
---|
1509 | |
---|
1510 | lemma minus_zero_to_le: ∀n,m:ℕ.n - m = 0 → n ≤ m. |
---|
1511 | #n |
---|
1512 | elim n |
---|
1513 | [ #m #_ @le_O_n |
---|
1514 | | #n' #Hind #m cases m |
---|
1515 | [ #H -n whd in match (minus ??) in H; >H @le_n |
---|
1516 | | #m' -m #H whd in match (minus ??) in H; @le_S_S @Hind @H |
---|
1517 | ] |
---|
1518 | ] |
---|
1519 | qed. |
---|
1520 | |
---|
1521 | lemma plus_zero_zero: ∀n,m:ℕ.n + m = 0 → m = 0. |
---|
1522 | #n #m #Hn @sym_eq @le_n_O_to_eq <Hn >commutative_plus @le_plus_n_r |
---|
1523 | qed. |
---|
1524 | |
---|
1525 | (* this can probably be done more simply somewhere *) |
---|
1526 | lemma not_true_is_false: |
---|
1527 | ∀b:bool.b ≠ true → b = false. |
---|
1528 | #b cases b |
---|
1529 | [ #H @⊥ @(absurd ?? H) @refl |
---|
1530 | | #H @refl |
---|
1531 | ] |
---|
1532 | qed. |
---|