2 ||M|| This file is part of HELM, an Hypertextual, Electronic
3 ||A|| Library of Mathematics, developed at the Computer Science
4 ||T|| Department of the University of Bologna, Italy.
8 \ / This file is distributed under the terms of the
9 \ / GNU General Public License Version 2
10 V_____________________________________________________________*)
12 include "turing/multi_universal/moves_2.ma".
13 include "turing/multi_universal/match.ma".
14 include "turing/multi_universal/copy.ma".
15 include "turing/multi_universal/alphabet.ma".
16 include "turing/multi_universal/tuples.ma".
19 definition obj ≝ (0:DeqNat).
20 definition cfg ≝ (1:DeqNat).
21 definition prg ≝ (2:DeqNat).
23 definition obj_to_cfg ≝
24 (ifTM ?? (inject_TM ? (test_null ?) 2 obj)
25 (copy_char_N obj cfg FSUnialpha 2)
26 (inject_TM ? (write FSUnialpha null) 2 cfg)
28 inject_TM ? (move_to_end FSUnialpha L) 2 cfg ·
29 mmove cfg FSUnialpha 2 R.
31 definition R_obj_to_cfg ≝ λt1,t2:Vector (tape FSUnialpha) 3.
33 nth cfg ? t1 (niltape ?) = midtape ? ls c [ ] →
34 (∀lso,x,rso.nth obj ? t1 (niltape ?) = midtape FSUnialpha lso x rso →
36 (mk_tape ? [ ] (option_hd ? (reverse ? (x::ls))) (tail ? (reverse ? (x::ls)))) cfg) ∧
37 (current ? (nth obj ? t1 (niltape ?)) = None ? →
39 (mk_tape ? [ ] (option_hd FSUnialpha (reverse ? (null::ls)))
40 (tail ? (reverse ? (null::ls)))) cfg).
43 axiom accRealize_to_Realize :
44 ∀sig,n.∀M:mTM sig n.∀Rtrue,Rfalse,acc.
45 M ⊨ [ acc: Rtrue, Rfalse ] → M ⊨ Rtrue ∪ Rfalse.
48 lemma eq_mk_tape_rightof :
49 ∀alpha,a,al.mk_tape alpha (a::al) (None ?) [ ] = rightof ? a al.
53 lemma tape_move_mk_tape_R :
55 (c = None ? → ls = [ ] ∨ rs = [ ]) →
56 tape_move ? (mk_tape sig ls c rs) R =
57 mk_tape ? (option_cons ? c ls) (option_hd ? rs) (tail ? rs).
58 #sig * [ * [ * | #c * ] | #l0 #ls0 * [ *
59 [| #r0 #rs0 #H @False_ind cases (H (refl ??)) #H1 destruct (H1) ] | #c * ] ]
63 lemma None_or_Some: ∀A.∀a. a =None A ∨ ∃b. a = Some ? b.
67 lemma not_None_to_Some: ∀A.∀a. a ≠ None A → ∃b. a = Some ? b.
68 #A * /2/ * #H @False_ind @H %
71 lemma sem_obj_to_cfg : obj_to_cfg ⊨ R_obj_to_cfg.
72 @(sem_seq_app FSUnialpha 2 ?????
74 (sem_test_null_multi ?? obj ?)
76 (sem_inject ???? cfg ? (sem_write FSUnialpha null)))
77 (sem_seq ?????? (sem_inject ???? cfg ? (sem_move_to_end_l ?))
78 (sem_move_multi ? 2 cfg R ?))) //
80 #tb * #Hif * #tc * #HM2 #HM3 #c #ls #Hcfg
83 [ * #t1 * * #Hcurta #Ht1 destruct (Ht1)
84 lapply (not_None_to_Some … Hcurta) * #curta #Hcurtaeq
85 whd in ⊢ (%→?); #Htb % [2: #Hcur @False_ind /2/]
86 #lso #xo #rso #Hobjta cases HM2 whd in ⊢ (%→?); * #_
87 #HM2 #Heq >Htb in HM2; >nth_change_vec [2: @leb_true_to_le %]
88 >Hcfg >Hcurtaeq #HM2 lapply (HM2 … (refl ??)) -HM2
89 whd in match (left ??); whd in match (right ??);
90 >reverse_cons #Htc >HM3 @(eq_vec … (niltape ?)) #i #lei2
91 cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
92 [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
93 [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
94 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
95 <(Heq 0) [2:@eqb_false_to_not_eq %] >Htb
96 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
97 >nth_change_vec_neq [%|2:@eqb_false_to_not_eq %]
98 |#Hi >Hi >nth_change_vec // >nth_change_vec // >Htc
99 >Hobjta in Hcurtaeq; whd in ⊢ (??%?→?); #Htmp destruct(Htmp)
100 >tape_move_mk_tape_R [2: #_ %1 %] %
102 |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
103 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
104 <(Heq 2) [2:@eqb_false_to_not_eq %] >Htb
105 >nth_change_vec_neq [%|2:@eqb_false_to_not_eq %]
107 | * #t1 * * #Hcurta #Ht1 destruct (Ht1)
108 * whd in ⊢ (%→?); #Htb lapply (Htb … Hcfg) -Htb #Htb
110 [#lso #xo #rso #Hmid @False_ind >Hmid in Hcurta;
111 whd in ⊢ (??%?→?); #Htmp destruct (Htmp)]
112 #_ cases HM2 whd in ⊢ (%→?); * #_
113 #HM2 #Heq >Htb in HM2; #HM2 lapply (HM2 … (refl ??)) -HM2
114 #Htc >HM3 @(eq_vec … (niltape ?)) #i #lei2
115 cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
116 [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
117 [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
118 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
119 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
120 <(Heq 0) [2:@eqb_false_to_not_eq %] >Htb
121 <(Htbeq 0) [2:@eqb_false_to_not_eq %] %
122 |#Hi >Hi >nth_change_vec // >nth_change_vec // >Htc
123 >tape_move_mk_tape_R [2: #_ %1 %] >reverse_cons %
125 |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
126 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
127 <(Heq 2) [2:@eqb_false_to_not_eq %]
128 <(Htbeq 2) [%|@eqb_false_to_not_eq %]
133 (* another semantics for obj_to_cfg *)
134 definition low_char' ≝ λc.
137 | Some b ⇒ if (is_bit b) then b else null
140 lemma low_char_option : ∀s.
141 low_char' (option_map FinBool FSUnialpha bit s) = low_char s.
145 definition R_obj_to_cfg1 ≝ λt1,t2:Vector (tape FSUnialpha) 3.
147 nth cfg ? t1 (niltape ?) = midtape ? ls c [ ] →
148 let x ≝ current ? (nth obj ? t1 (niltape ?)) in
149 (∀b. x= Some ? b → is_bit b = true) →
150 t2 = change_vec ?? t1
151 (mk_tape ? [ ] (option_hd FSUnialpha (reverse ? (low_char' x::ls)))
152 (tail ? (reverse ? (low_char' x::ls)))) cfg.
154 lemma sem_obj_to_cfg1: obj_to_cfg ⊨ R_obj_to_cfg1.
155 @(Realize_to_Realize … sem_obj_to_cfg) #t1 #t2 #Hsem
156 #c #ls #Hcfg lapply(Hsem c ls Hcfg) * #HSome #HNone #Hb
157 cases (None_or_Some ? (current ? (nth obj ? t1 (niltape ?))))
158 [#Hcur >Hcur @HNone @Hcur
160 cut (low_char' (Some ? b) = b) [whd in ⊢ (??%?); >(Hb b Hb1) %] #Hlow >Hlow
161 lapply(current_to_midtape … Hb1) * #lsobj * #rsobj #Hmid
167 definition test_null_char ≝ test_char FSUnialpha (λc.c == null).
169 definition R_test_null_char_true ≝ λt1,t2.
170 current FSUnialpha t1 = Some ? null ∧ t1 = t2.
172 definition R_test_null_char_false ≝ λt1,t2.
173 current FSUnialpha t1 ≠ Some ? null ∧ t1 = t2.
175 lemma sem_test_null_char :
176 test_null_char ⊨ [ tc_true : R_test_null_char_true, R_test_null_char_false].
177 #t1 cases (sem_test_char FSUnialpha (λc.c == null) t1) #k * #outc * * #Hloop #Htrue
178 #Hfalse %{k} %{outc} % [ %
180 | #Houtc cases (Htrue ?) [| @Houtc] * #c * #Hcurt1 #Hcnull lapply (\P Hcnull)
181 -Hcnull #H destruct (H) #Houtc1 %
182 [ @Hcurt1 | <Houtc1 % ] ]
183 | #Houtc cases (Hfalse ?) [| @Houtc] #Hc #Houtc %
184 [ % #Hcurt1 >Hcurt1 in Hc; #Hc lapply (Hc ? (refl ??))
185 >(?:((null:FSUnialpha) == null) = true) [|@(\b (refl ??)) ]
190 definition cfg_to_obj ≝
191 mmove cfg FSUnialpha 2 L ·
192 (ifTM ?? (inject_TM ? test_null_char 2 cfg)
194 (copy_char_N cfg obj FSUnialpha 2)
197 inject_TM ? (move_to_end FSUnialpha L) 2 cfg ·
198 mmove cfg FSUnialpha 2 R. *)
200 definition R_cfg_to_obj ≝ λt1,t2:Vector (tape FSUnialpha) 3.
202 nth cfg ? t1 (niltape ?) = mk_tape FSUnialpha (c::ls) (None ?) [ ] →
203 (c = null → t2 = change_vec ?? t1 (midtape ? ls c [ ]) cfg) ∧
207 (midtape ? (left ? (nth obj ? t1 (niltape ?))) c (right ? (nth obj ? t1 (niltape ?)))) obj)
208 (midtape ? ls c [ ]) cfg).
210 lemma tape_move_mk_tape_L :
212 (c = None ? → ls = [ ] ∨ rs = [ ]) →
213 tape_move ? (mk_tape sig ls c rs) L =
214 mk_tape ? (tail ? ls) (option_hd ? ls) (option_cons ? c rs).
215 #sig * [ * [ * | #c * ] | #l0 #ls0 * [ *
216 [| #r0 #rs0 #H @False_ind cases (H (refl ??)) #H1 destruct (H1) ] | #c * ] ]
220 lemma sem_cfg_to_obj : cfg_to_obj ⊨ R_cfg_to_obj.
221 @(sem_seq_app FSUnialpha 2 ????? (sem_move_multi ? 2 cfg L ?)
223 (acc_sem_inject ?????? cfg ? sem_test_null_char)
225 (sem_copy_char_N …)))
228 #tc * whd in ⊢ (%→?); #Htc *
229 [ * #te * * * #Hcurtc #Hte1 #Hte2 whd in ⊢ (%→?); #Htb destruct (Htb)
231 [ #Hc >Hta in Htc; >eq_mk_tape_rightof whd in match (tape_move ???); #Htc
233 [ lapply (eq_vec_change_vec ??????? (sym_eq … Hte1) Hte2) >change_vec_same // ]
235 | #Hc >Hta in Htc; >eq_mk_tape_rightof whd in match (tape_move ???); #Htc
236 >Htc in Hcurtc; >nth_change_vec // normalize in ⊢ (%→?);
237 #H destruct (H) @False_ind cases Hc /2/ ]
238 | * #te * * * #Hcurtc #Hte1 #Hte2
241 [ >Htc in Hcurtc; >Hta >nth_change_vec //
242 normalize in ⊢ (%→?); * #H @False_ind /2/
244 [ lapply (eq_vec_change_vec ??????? (sym_eq … Hte1) Hte2)
245 >change_vec_same // ] -Hte1 -Hte2 #Hte destruct (Hte)
246 >Hta in Htc; whd in match (tape_move ???); #Htc
247 >Htc in Htb; >nth_change_vec //
248 >nth_change_vec_neq [2:@eqb_false_to_not_eq //] >Hta
253 definition char_to_move ≝ λc.match c with
254 [ bit b ⇒ if b then R else L
257 definition char_to_bit_option ≝ λc.match c with
258 [ bit b ⇒ Some ? (bit b)
261 definition R_cfg_to_obj1 ≝ λt1,t2:Vector (tape FSUnialpha) 3.
263 nth cfg ? t1 (niltape ?) = mk_tape FSUnialpha (c::ls) (None ?) [ ] →
266 tape_write ? (nth obj ? t1 (niltape ?)) (char_to_bit_option c) in
269 (tape_write ? (nth obj ? t1 (niltape ?)) (char_to_bit_option c)) obj)
270 (midtape ? ls c [ ]) cfg.
272 lemma sem_cfg_to_obj1: cfg_to_obj ⊨ R_cfg_to_obj1.
273 @(Realize_to_Realize … sem_cfg_to_obj) #t1 #t2 #H #c #ls #Hcfg #Hbar
274 cases (H c ls Hcfg) cases (true_or_false (c==null)) #Hc
275 [#Ht2 #_ >(Ht2 (\P Hc)) -Ht2 @(eq_vec … (niltape ?))
276 #i #lei2 cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
277 [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
278 [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
279 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
280 >nth_change_vec_neq in ⊢ (???%); [2:@eqb_false_to_not_eq %]
281 >nth_change_vec // >(\P Hc) %
282 |#Hi >Hi >nth_change_vec //
284 |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
285 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
286 >nth_change_vec_neq [2:@eqb_false_to_not_eq %] %
288 |#_ #Ht2 >(Ht2 (\Pf Hc)) -Ht2 @(eq_vec … (niltape ?))
289 #i #lei2 cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
290 [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
291 [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
292 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
293 >nth_change_vec_neq in ⊢ (???%); [2:@eqb_false_to_not_eq %]
294 >nth_change_vec // >nth_change_vec //
295 lapply (\bf Hbar) lapply Hc elim c //
296 [whd in ⊢ (??%?→?); #H destruct (H)
297 |#_ whd in ⊢ (??%?→?); #H destruct (H)
299 |#Hi >Hi >nth_change_vec //
301 |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
302 >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
303 >nth_change_vec_neq [2:@eqb_false_to_not_eq %] %
309 (* macchina che muove il nastro obj a destra o sinistra a seconda del valore
310 del current di prg, che codifica la direzione in cui ci muoviamo *)
312 definition tape_move_obj : mTM FSUnialpha 2 ≝
314 (inject_TM ? (test_char ? (λc:FSUnialpha.c == bit false)) 2 prg)
315 (mmove obj FSUnialpha 2 L)
317 (inject_TM ? (test_char ? (λc:FSUnialpha.c == bit true)) 2 prg)
318 (mmove obj FSUnialpha 2 R)
323 definition R_tape_move_obj' ≝ λt1,t2:Vector (tape FSUnialpha) 3.
324 (current ? (nth prg ? t1 (niltape ?)) = Some ? (bit false) →
325 t2 = change_vec ?? t1 (tape_move ? (nth obj ? t1 (niltape ?)) L) obj) ∧
326 (current ? (nth prg ? t1 (niltape ?)) = Some ? (bit true) →
327 t2 = change_vec ?? t1 (tape_move ? (nth obj ? t1 (niltape ?)) R) obj) ∧
328 (current ? (nth prg ? t1 (niltape ?)) ≠ Some ? (bit false) →
329 current ? (nth prg ? t1 (niltape ?)) ≠ Some ? (bit true) →
332 lemma sem_tape_move_obj' : tape_move_obj ⊨ R_tape_move_obj'.
333 #ta cases (sem_if ??????????
334 (acc_sem_inject ?????? prg ? (sem_test_char ? (λc:FSUnialpha.c == bit false)))
335 (sem_move_multi ? 2 obj L ?)
337 (acc_sem_inject ?????? prg ? (sem_test_char ? (λc:FSUnialpha.c == bit true)))
338 (sem_move_multi ? 2 obj R ?)
340 #i * #outc * #Hloop #HR %{i} %{outc} % [@Hloop] -i
342 [ * #tb * * * * #c * #Hcurta_prg #Hc lapply (\P Hc) -Hc #Hc #Htb1 #Htb2
343 whd in ⊢ (%→%); #Houtc >Houtc -Houtc % [ %
344 [ >Hcurta_prg #H destruct (H) >(?:tb = ta)
345 [| lapply (eq_vec_change_vec ??????? Htb1 Htb2)
346 >change_vec_same // ] %
347 | >Hcurta_prg #H destruct (H) destruct (Hc) ]
348 | >Hcurta_prg >Hc * #H @False_ind /2/ ]
349 | * #tb * * * #Hnotfalse #Htb1 #Htb2 cut (tb = ta)
350 [ lapply (eq_vec_change_vec ??????? Htb1 Htb2)
351 >change_vec_same // ] -Htb1 -Htb2 #Htb destruct (Htb) *
352 [ * #tc * * * * #c * #Hcurta_prg #Hc lapply (\P Hc) -Hc #Hc #Htc1 #Htc2
353 whd in ⊢ (%→%); #Houtc >Houtc -Houtc % [ %
354 [ >Hcurta_prg #H destruct (H) destruct (Hc)
355 | >Hcurta_prg #H destruct (H) >(?:tc = ta)
356 [| lapply (eq_vec_change_vec ??????? Htc1 Htc2)
357 >change_vec_same // ] % ]
358 | >Hcurta_prg >Hc #_ * #H @False_ind /2/ ]
359 | * #tc * * * #Hnottrue #Htc1 #Htc2 cut (tc = ta)
360 [ lapply (eq_vec_change_vec ??????? Htc1 Htc2)
361 >change_vec_same // ] -Htc1 -Htc2
362 #Htc destruct (Htc) whd in ⊢ (%→?); #Houtc % [ %
363 [ #Hcurta_prg lapply (\Pf (Hnotfalse ? Hcurta_prg)) * #H @False_ind /2/
364 | #Hcurta_prg lapply (\Pf (Hnottrue ? Hcurta_prg)) * #H @False_ind /2/ ]
370 definition R_tape_move_obj ≝ λt1,t2:Vector (tape FSUnialpha) 3.
371 ∀c. current ? (nth prg ? t1 (niltape ?)) = Some ? c →
372 t2 = change_vec ?? t1 (tape_move ? (nth obj ? t1 (niltape ?)) (char_to_move c)) obj.
374 lemma sem_tape_move_obj : tape_move_obj ⊨ R_tape_move_obj.
375 @(Realize_to_Realize … sem_tape_move_obj')
376 #ta #tb * * #Htb1 #Htb2 #Htb3 * [ *
378 | #Hcurta_prg change with (nth obj ? ta (niltape ?)) in match (tape_move ???);
379 >change_vec_same @Htb3 >Hcurta_prg % #H destruct (H)
380 | #Hcurta_prg change with (nth obj ? ta (niltape ?)) in match (tape_move ???);
381 >change_vec_same @Htb3 >Hcurta_prg % #H destruct (H)
385 (************** list of tape ******************)
386 definition list_of_tape ≝ λsig.λt:tape sig.
387 reverse ? (left ? t)@option_cons ? (current ? t) (right ? t).
389 lemma list_of_midtape: ∀sig,ls,c,rs.
390 list_of_tape sig (midtape ? ls c rs) = reverse ? ls@c::rs.
393 lemma list_of_rightof: ∀sig,ls,c.
394 list_of_tape sig (rightof ? c ls) = reverse ? (c::ls).
395 #sig #ls #c <(append_nil ? (reverse ? (c::ls)))
398 lemma list_of_tape_move: ∀sig,t,m.
399 list_of_tape sig t = list_of_tape sig (tape_move ? t m).
400 #sig #t * // cases t //
401 [(* rightof, move L *) #a #l >list_of_midtape
402 >append_cons <reverse_single <reverse_append %
403 |(* midtape, move L *) * //
404 #a #ls #c #rs >list_of_midtape >list_of_midtape
405 >reverse_cons >associative_append %
406 |(* midtape, move R *) #ls #c *
407 [>list_of_midtape >list_of_rightof >reverse_cons %
408 |#a #rs >list_of_midtape >list_of_midtape >reverse_cons
409 >associative_append %
414 lemma list_of_tape_write: ∀sig,cond,t,c.
415 (∀b. c = Some ? b → cond b =true) →
416 (∀x. mem ? x (list_of_tape ? t) → cond x =true ) →
417 ∀x. mem ? x (list_of_tape sig (tape_write ? t c)) → cond x =true.
418 #sig #cond #t #c #Hc #Htape #x lapply Hc cases c
419 [(* c is None *) #_ whd in match (tape_write ???); @Htape
420 |#b #Hb lapply (Hb … (refl ??)) -Hb #Hb
421 whd in match (tape_write ???); >list_of_midtape
422 #Hx cases(mem_append ???? Hx) -Hx
423 [#Hx @Htape @mem_append_l1 @Hx
425 #Hx @Htape @mem_append_l2 cases (current sig t)
431 lemma current_in_list: ∀sig,t,b.
432 current sig t = Some ? b → mem ? b (list_of_tape sig t).
434 [whd in ⊢ (??%?→?); #Htmp destruct
435 |#l #b whd in ⊢ (??%?→?); #Htmp destruct
436 |#l #b whd in ⊢ (??%?→?); #Htmp destruct
437 |#ls #c #rs whd in ⊢ (??%?→?); #Htmp destruct
438 >list_of_midtape @mem_append_l2 % %
442 definition restart_tape ≝ λi,n.
443 mmove i FSUnialpha n L ·
444 inject_TM ? (move_to_end FSUnialpha L) n i ·
445 mmove i FSUnialpha n R.
447 definition R_restart_tape ≝ λi,n.λint,outt:Vector (tape FSUnialpha) (S n).
448 ∀t.t = nth i ? int (niltape ?) →
449 outt = change_vec ?? int
450 (mk_tape ? [ ] (option_hd ? (list_of_tape ? t)) (tail ? (list_of_tape ? t))) i.
452 lemma sem_restart_tape : ∀i,n.i < S n → restart_tape i n ⊨ R_restart_tape i n.
454 @(sem_seq_app ??????? (sem_move_multi ? n i L ?)
455 (sem_seq ?????? (sem_inject ???? i ? (sem_move_to_end_l ?))
456 (sem_move_multi ? n i R ?))) [1,2,3:@le_S_S_to_le //]
457 #ta #tb * #tc * whd in ⊢ (%→?); #Htc
458 * #td * * * #Htd1 #Htd2 #Htd3
459 whd in ⊢ (%→?); #Htb *
460 [ #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
462 [ <(change_vec_same … tc … i … (niltape ?))
463 @(eq_vec_change_vec … (niltape ?))
464 [ @Htd1 >Htc >nth_change_vec //
466 (* >Htc in Htd1; >nth_change_vec // *) -Htd1 -Htd2 -Htd3
467 #Htd >Htd in Htb; >Htc >change_vec_change_vec >nth_change_vec //
469 | #r0 #rs0 #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
471 [ <(change_vec_same … tc … i … (niltape ?))
472 @(eq_vec_change_vec … (niltape ?))
473 [ @Htd1 >Htc >nth_change_vec //
475 (* >Htc in Htd1; >nth_change_vec // *) -Htd1 -Htd2 -Htd3
476 #Htd >Htd in Htb; >Htc >change_vec_change_vec >nth_change_vec //
478 | #l0 #ls0 #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
479 cut (td = change_vec ?? tc (mk_tape ? [ ] (None ?) (reverse ? ls0@[l0])) i)
480 [ <(change_vec_same … tc … i … (niltape ?))
481 @(eq_vec_change_vec … (niltape ?))
482 [ @Htd2 >Htc >nth_change_vec //
483 | #j #Hij >nth_change_vec_neq // @Htd3 // ]]
484 #Htd >Htd in Htb; >Htc >change_vec_change_vec >change_vec_change_vec
485 >nth_change_vec // #Htb >Htb <(reverse_reverse ? ls0) in ⊢ (???%);
486 cases (reverse ? ls0)
488 | #l1 #ls1 >reverse_cons
489 >(?: list_of_tape ? (rightof ? l0 (reverse ? ls1@[l1])) =
491 [|change with (reverse ??@?) in ⊢ (??%?);
492 whd in match (left ??); >reverse_cons >reverse_append
493 whd in ⊢ (??%?); @eq_f >reverse_reverse normalize >append_nil % ] % ]
495 [ #c #rs #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
497 [ <(change_vec_same … tc … i … (niltape ?))
498 @(eq_vec_change_vec … (niltape ?))
499 [ @Htd1 >Htc >nth_change_vec //
501 (* >Htc in Htd1; >nth_change_vec // *) -Htd1 -Htd2 -Htd3
502 #Htd >Htd in Htb; >Htc >change_vec_change_vec >nth_change_vec //
504 | #l0 #ls0 #c #rs #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
505 cut (td = change_vec ?? tc (mk_tape ? [ ] (None ?) (reverse ? ls0@l0::c::rs)) i)
506 [ @(eq_vec_change_vec … (niltape ?))
507 [ @Htd2 >Htc >nth_change_vec //
509 #Htd >Htd in Htb; >Htc >change_vec_change_vec >change_vec_change_vec
510 >nth_change_vec // #Htb >Htb <(reverse_reverse ? ls0) in ⊢ (???%);
511 cases (reverse ? ls0)
513 | #l1 #ls1 >reverse_cons
514 >(?: list_of_tape ? (midtape ? (l0::reverse ? ls1@[l1]) c rs) =
516 [|change with (reverse ??@?) in ⊢ (??%?);
517 whd in match (left ??); >reverse_cons >reverse_append
518 whd in ⊢ (??%?); @eq_f >reverse_reverse normalize
519 >associative_append % ] % ]