X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Flib%2Fturing%2Fmulti_universal%2Funistep_aux.ma;h=8033c222627b6123481c324d528aab44652260aa;hb=31790e8f6fa051f710f41e4c17d67701874ba331;hp=06427b3bb638889731844709de706c61c39f0e50;hpb=e461bb10382fe2ea65bd37dd56be46c6aec67db7;p=helm.git

diff --git a/matita/matita/lib/turing/multi_universal/unistep_aux.ma b/matita/matita/lib/turing/multi_universal/unistep_aux.ma
index 06427b3bb..8033c2226 100644
--- a/matita/matita/lib/turing/multi_universal/unistep_aux.ma
+++ b/matita/matita/lib/turing/multi_universal/unistep_aux.ma
@@ -9,202 +9,513 @@
      \ /   GNU General Public License Version 2   
       V_____________________________________________________________*)
 
-include "turing/multi_universal/moves_2.ma".
-include "turing/multi_universal/match.ma".
-include "turing/multi_universal/copy.ma".
+include "turing/auxiliary_machines.ma".
+include "turing/auxiliary_multi_machines.ma".
 include "turing/multi_universal/alphabet.ma".
+include "turing/multi_universal/tuples.ma".
 
-(*
-
-  in.obj : ...  x ...
-                ^
-  in.cfg : ...  ? ? ...
-                    ^
-                
-  out.cfg : ... 1 x ...
-                  ^
-                  
-  ---------------------
-  current (in.obj) = None
-  
-  in.cfg : ...  ? ? ...
-                    ^
-
-  out.cfg : ... 0 0 ...
-                  ^
-                  
-  obj_to_cfg ≝ 
-    move_l(cfg);
-    move_l(cfg);
-    (if (current(in.obj)) == None
-       then write(0,cfg);
-            move_r(cfg);
-            write(0,cfg);
-       else write(1,cfg);
-            move_r(cfg);
-            copy_step(obj,cfg);
-            move_l(obj);)
-    move_to_end_l(cfg);
-    move_r(cfg);
-       
-  
-  cfg_to_obj
-*)
 
-definition obj ≝ 0.
-definition cfg ≝ 1.
-definition prg ≝ 2.
+definition obj ≝ (0:DeqNat).
+definition cfg ≝ (1:DeqNat).
+definition prg ≝ (2:DeqNat).
 
 definition obj_to_cfg ≝
-  mmove cfg FSUnialpha 2 L ·
-  mmove cfg FSUnialpha 2 L ·
   (ifTM ?? (inject_TM ? (test_null ?) 2 obj)
-    (inject_TM ? (write FSUnialpha (bit false)) 2 cfg ·
-     inject_TM ? (move_r FSUnialpha) 2 cfg ·
-     inject_TM ? (write FSUnialpha (bit false)) 2 cfg)
-    (inject_TM ? (write FSUnialpha (bit true)) 2 cfg ·
-     inject_TM ? (move_r FSUnialpha) 2 cfg ·
-     copy_step obj cfg FSUnialpha 2) tc_true ·
-     inject_TM ? (move_l FSUnialpha) 2 cfg) ·
+    (copy_char_N obj cfg FSUnialpha 2)
+    (inject_TM ? (write FSUnialpha null) 2 cfg)
+     tc_true) ·
   inject_TM ? (move_to_end FSUnialpha L) 2 cfg ·
-  inject_TM ? (move_r FSUnialpha) 2 cfg.
+  mmove cfg FSUnialpha 2 R.
   
 definition R_obj_to_cfg ≝ λt1,t2:Vector (tape FSUnialpha) 3.
-  ∀c,opt,ls.
-  nth cfg ? t1 (niltape ?) = mk_tape FSUnialpha (c::opt::ls) (None ?) [ ] → 
+  ∀c,ls.
+  nth cfg ? t1 (niltape ?) = midtape ? ls c [ ] → 
   (∀lso,x,rso.nth obj ? t1 (niltape ?) = midtape FSUnialpha lso x rso → 
    t2 = change_vec ?? t1 
-         (mk_tape ? [ ] (option_hd ? (reverse ? (c::opt::ls))) (tail ? (reverse ? (c::opt::ls)))) cfg) ∧
+         (mk_tape ? [ ] (option_hd ? (reverse ? (x::ls))) (tail ? (reverse ? (x::ls)))) cfg) ∧
   (current ? (nth obj ? t1 (niltape ?)) = None ? → 
    t2 = change_vec ?? t1
-         (mk_tape ? [ ] (option_hd FSUnialpha (reverse ? (bit false::bit false::ls))) 
-           (tail ? (reverse ? (bit false :: bit false::ls)))) cfg).
-           
-axiom sem_move_to_end_l : ∀sig. move_to_end sig L ⊨ R_move_to_end_l sig.
+         (mk_tape ? [ ] (option_hd FSUnialpha (reverse ? (null::ls))) 
+           (tail ? (reverse ? (null::ls)))) cfg).
+
+(*
+axiom accRealize_to_Realize :
+  ∀sig,n.∀M:mTM sig n.∀Rtrue,Rfalse,acc.
+  M ⊨ [ acc: Rtrue, Rfalse ] →  M ⊨ Rtrue ∪ Rfalse.
+*)
+  
+lemma eq_mk_tape_rightof :
+ ∀alpha,a,al.mk_tape alpha (a::al) (None ?) [ ] = rightof ? a al.
+#alpha #a #al %
+qed.
+
+lemma tape_move_mk_tape_R :
+  ∀sig,ls,c,rs.
+  (c = None ? → ls = [ ] ∨ rs = [ ]) → 
+  tape_move ? (mk_tape sig ls c rs) R =
+  mk_tape ? (option_cons ? c ls) (option_hd ? rs) (tail ? rs).
+#sig * [ * [ * | #c * ] | #l0 #ls0 * [ *
+[| #r0 #rs0 #H @False_ind cases (H (refl ??)) #H1 destruct (H1) ] | #c * ] ] 
+normalize //
+qed.
+
+lemma None_or_Some: ∀A.∀a. a =None A ∨ ∃b. a = Some ? b.
+#A * /2/ #a %2 %{a} %
+qed.
+
+lemma not_None_to_Some: ∀A.∀a. a ≠ None A → ∃b. a = Some ? b.
+#A * /2/ * #H @False_ind @H %
+qed. 
 
 lemma sem_obj_to_cfg : obj_to_cfg ⊨  R_obj_to_cfg.
-@(sem_seq_app FSUnialpha 2 ????? (sem_move_multi ? 2 cfg L ?)
-  (sem_seq_app ?? ????? (sem_move_multi ? 2 cfg L ?)
-   (sem_seq_app ???????    
-    (sem_seq_app ???????
-     (sem_if ? 2 ????????
-      (sem_test_null_multi ?? obj ?)
-      (sem_seq_app ??????? (sem_inject ???? cfg ? (sem_write FSUnialpha (bit false)))
-       (sem_seq_app ??????? (sem_inject ???? cfg ? (sem_move_r ?)) 
-        (sem_inject ???? cfg ? (sem_write FSUnialpha (bit false))) ?) ?)
-      ?)
-     ??) ??) ?) ?)
-[|||||||||||||||| @     
-        
-        ??) ??) ??) ?) ?)
-       ?) ?) ?) ?)
-
-
-@(sem_seq_app FSUnialpha 2 ????? (sem_move_multi ? 2 cfg L ?) ??)
-[||
-@(sem_seq_app ?? ????? (sem_move_multi ? 2 cfg L ?) ??)
-[|| @sem_seq_app
-[|| @sem_seq_app
-[|| @(sem_if ? 2 ???????? (sem_test_null_multi ?? obj ?))
-[|||@(sem_seq_app ??????? (sem_inject ???? cfg ? (sem_write FSUnialpha (bit false))) ?)
-[||@(sem_seq_app ??????? (sem_inject ???? cfg ? (sem_move_r ?)) 
-       (sem_inject ???? cfg ? (sem_write FSUnialpha (bit false))) ?)
-[||      
+@(sem_seq_app FSUnialpha 2 ????? 
+  (sem_if ??????????
+   (sem_test_null_multi ?? obj ?)
+   (sem_copy_char_N …)
+   (sem_inject ???? cfg ? (sem_write FSUnialpha null)))
+  (sem_seq ?????? (sem_inject ???? cfg ? (sem_move_to_end_l ?))
+    (sem_move_multi ? 2 cfg R ?))) //
+#ta #tout *
+#tb * #Hif * #tc * #HM2 #HM3 #c #ls #Hcfg
+(* Hif *)
+cases Hif -Hif
+[ * #t1 * * #Hcurta #Ht1 destruct (Ht1)
+  lapply (not_None_to_Some … Hcurta) * #curta #Hcurtaeq
+  whd in ⊢ (%→?); #Htb % [2: #Hcur @False_ind /2/]
+  #lso #xo #rso #Hobjta cases HM2 whd in ⊢ (%→?); * #_
+  #HM2 #Heq >Htb in HM2; >nth_change_vec [2: @leb_true_to_le %]
+  >Hcfg >Hcurtaeq #HM2 lapply (HM2 … (refl ??)) -HM2 
+  whd in match (left ??); whd in match (right ??);
+  >reverse_cons #Htc >HM3 @(eq_vec … (niltape ?)) #i #lei2 
+  cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
+  [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
+    [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+     <(Heq 0) [2:@eqb_false_to_not_eq %] >Htb
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     >nth_change_vec_neq [%|2:@eqb_false_to_not_eq %] 
+    |#Hi >Hi >nth_change_vec // >nth_change_vec // >Htc
+     >Hobjta in Hcurtaeq; whd in ⊢ (??%?→?); #Htmp destruct(Htmp)
+     >tape_move_mk_tape_R [2: #_ %1 %] %
+    ]
+  |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+   >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+   <(Heq 2) [2:@eqb_false_to_not_eq %] >Htb
+   >nth_change_vec_neq [%|2:@eqb_false_to_not_eq %] 
+  ]
+| * #t1 * * #Hcurta #Ht1 destruct (Ht1)
+  * whd in ⊢ (%→?); #Htb lapply (Htb … Hcfg) -Htb #Htb
+  #Htbeq % 
+    [#lso #xo #rso #Hmid @False_ind >Hmid in Hcurta;
+     whd in ⊢ (??%?→?); #Htmp destruct (Htmp)]
+  #_ cases HM2 whd in ⊢ (%→?); * #_
+  #HM2 #Heq >Htb in HM2; #HM2 lapply (HM2 … (refl ??)) -HM2 
+  #Htc >HM3 @(eq_vec … (niltape ?)) #i #lei2 
+  cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
+  [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
+    [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     <(Heq 0) [2:@eqb_false_to_not_eq %] >Htb
+     <(Htbeq 0) [2:@eqb_false_to_not_eq %] % 
+    |#Hi >Hi >nth_change_vec // >nth_change_vec // >Htc
+     >tape_move_mk_tape_R [2: #_ %1 %] >reverse_cons % 
+    ]
+  |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+   >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+   <(Heq 2) [2:@eqb_false_to_not_eq %] 
+   <(Htbeq 2) [%|@eqb_false_to_not_eq %] 
+  ]
+]
+qed.
 
-@(sem_seq_app FSUnialpha 2 ????? (sem_move_multi ? 2 cfg L ?)
-  (sem_seq_app ?? ????? (sem_move_multi ? 2 cfg L ?)
-   (sem_seq_app ???????
-    (sem_if ? 2 ????????
-     (sem_test_null_multi ?? obj ?)
-     (sem_seq_app ??????? (sem_inject ???? cfg ? (sem_write FSUnialpha (bit false)))     
-      (sem_seq_app ??????? (sem_inject ???? cfg ? (sem_move_r ?)) 
-       (sem_inject ???? cfg ? (sem_write FSUnialpha (bit false))) ?) ?)
-       ?)
-    (sem_seq_app ??????? (sem_inject ???? cfg ? (sem_move_to_end_l ?))
-     (sem_inject ???? cfg ? (sem_move_r ?)) ?) ?) ?) ?)
-      
+(* another semantics for obj_to_cfg *)
+definition low_char' ≝ λc.
+  match c with
+  [ None ⇒ null 
+  | Some b ⇒ if (is_bit b) then b else null
+  ].
+  
+lemma low_char_option : ∀s.
+  low_char' (option_map FinBool FSUnialpha bit s) = low_char s.
+* //
+qed.
+
+definition R_obj_to_cfg1 ≝ λt1,t2:Vector (tape FSUnialpha) 3.
+  ∀c,ls.
+  nth cfg ? t1 (niltape ?) = midtape ? ls c [ ] → 
+  let x ≝ current ? (nth obj ? t1 (niltape ?)) in
+  (∀b. x= Some ? b → is_bit b = true) →
+  t2 = change_vec ?? t1
+         (mk_tape ? [ ] (option_hd FSUnialpha (reverse ? (low_char' x::ls))) 
+           (tail ? (reverse ? (low_char' x::ls)))) cfg.
 
-lemma wsem_copy : ∀src,dst,sig,n.src ≠ dst → src < S n → dst < S n → 
-  copy src dst sig n ⊫ R_copy src dst sig n.
-#src #dst #sig #n #Hneq #Hsrc #Hdst #ta #k #outc #Hloop
-lapply (sem_while … (sem_copy_step src dst sig n Hneq Hsrc Hdst) … Hloop) //
--Hloop * #tb * #Hstar @(star_ind_l ??????? Hstar) -Hstar
-[ whd in ⊢ (%→?); * #Hnone #Hout %
-  [#_ @Hout
-  |#ls #x #x0 #rs #ls0 #rs0 #Hsrc1 #Hdst1 @False_ind cases Hnone
-    [>Hsrc1 normalize #H destruct (H) | >Hdst1 normalize #H destruct (H)]
+lemma sem_obj_to_cfg1: obj_to_cfg ⊨ R_obj_to_cfg1.
+@(Realize_to_Realize … sem_obj_to_cfg) #t1 #t2 #Hsem
+#c #ls #Hcfg lapply(Hsem c ls Hcfg) * #HSome #HNone #Hb 
+cases (None_or_Some ? (current ? (nth obj ? t1 (niltape ?)))) 
+  [#Hcur >Hcur @HNone @Hcur
+  |* #b #Hb1 >Hb1
+   cut (low_char' (Some ? b) = b)  [whd in ⊢ (??%?); >(Hb b Hb1) %] #Hlow >Hlow
+   lapply(current_to_midtape … Hb1) * #lsobj * #rsobj #Hmid
+   @(HSome … Hmid)
   ]
-|#tc #td * #x * #y * * #Hcx #Hcy #Htd #Hstar #IH #He lapply (IH He) -IH *
- #IH1 #IH2 %
-  [* [>Hcx #H destruct (H) | >Hcy #H destruct (H)]
-  |#ls #x' #y' #rs #ls0 #rs0 #Hnth_src #Hnth_dst
-   >Hnth_src in Hcx; whd in ⊢ (??%?→?); #H destruct (H)
-   >Hnth_dst in Hcy; whd in ⊢ (??%?→?); #H destruct (H)
-   >Hnth_src in Htd; >Hnth_dst -Hnth_src -Hnth_dst
-   cases rs
-    [(* the source tape is empty after the move *)
-     #Htd lapply (IH1 ?) 
-      [%1 >Htd >nth_change_vec_neq [2:@(not_to_not … Hneq) //] >nth_change_vec //]
-     #Hout (* whd in match (tape_move ???); *) %1 %{([])} %{rs0} % 
-      [% [// | // ] 
-      |whd in match (reverse ??); whd in match (reverse ??);
-       >Hout >Htd @eq_f2 // cases rs0 //
-      ]
-    |#c1 #tl1 cases rs0
-      [(* the dst tape is empty after the move *)
-       #Htd lapply (IH1 ?) [%2 >Htd >nth_change_vec //] 
-       #Hout (* whd in match (tape_move ???); *) %2 %{[ ]} %{(c1::tl1)} % 
-        [% [// | // ] 
-        |whd in match (reverse ??); whd in match (reverse ??);
-         >Hout >Htd @eq_f2 // 
-        ]
-      |#c2 #tl2 whd in match (tape_move_mono ???); whd in match (tape_move_mono ???);
-       #Htd
-       cut (nth src (tape sig) td (niltape sig)=midtape sig (x::ls) c1 tl1)
-         [>Htd >nth_change_vec_neq [2:@(not_to_not … Hneq) //] @nth_change_vec //]
-       #Hsrc_td
-       cut (nth dst (tape sig) td (niltape sig)=midtape sig (x::ls0) c2 tl2)
-         [>Htd @nth_change_vec //]
-       #Hdst_td cases (IH2 … Hsrc_td Hdst_td) -Hsrc_td -Hdst_td
-        [* #rs01 * #rs02 * * #H1 #H2 #H3 %1
-         %{(c2::rs01)} %{rs02} % [% [@eq_f //|normalize @eq_f @H2]]
-         >Htd in H3; >change_vec_commute // >change_vec_change_vec
-         >change_vec_commute [2:@(not_to_not … Hneq) //] >change_vec_change_vec 
-         #H >reverse_cons >associative_append >associative_append @H 
-        |* #rs11 * #rs12 * * #H1 #H2 #H3 %2
-         %{(c1::rs11)} %{rs12} % [% [@eq_f //|normalize @eq_f @H2]]
-         >Htd in H3; >change_vec_commute // >change_vec_change_vec
-         >change_vec_commute [2:@(not_to_not … Hneq) //] >change_vec_change_vec 
-         #H >reverse_cons >associative_append >associative_append @H 
+qed.
+    
+(* test_null_char *)
+definition test_null_char ≝ test_char FSUnialpha (λc.c == null).
+
+definition R_test_null_char_true ≝ λt1,t2.
+  current FSUnialpha t1 = Some ? null ∧ t1 = t2.
+  
+definition R_test_null_char_false ≝ λt1,t2.
+  current FSUnialpha t1 ≠ Some ? null ∧ t1 = t2.
+  
+lemma sem_test_null_char :
+  test_null_char ⊨ [ tc_true : R_test_null_char_true, R_test_null_char_false].
+#t1 cases (sem_test_char FSUnialpha (λc.c == null) t1) #k * #outc * * #Hloop #Htrue
+#Hfalse %{k} %{outc} % [ %
+[ @Hloop
+| #Houtc cases (Htrue ?) [| @Houtc] * #c * #Hcurt1 #Hcnull lapply (\P Hcnull)
+  -Hcnull #H destruct (H) #Houtc1 %
+  [ @Hcurt1 | <Houtc1 % ] ]
+| #Houtc cases (Hfalse ?) [| @Houtc] #Hc #Houtc %
+  [ % #Hcurt1 >Hcurt1 in Hc; #Hc lapply (Hc ? (refl ??)) 
+    >(?:((null:FSUnialpha) == null) = true) [|@(\b (refl ??)) ]
+    #H destruct (H)
+  | <Houtc % ] ]
+qed.
+
+definition cfg_to_obj ≝
+  mmove cfg FSUnialpha 2 L ·
+  (ifTM ?? (inject_TM ? test_null_char 2 cfg)
+    (nop ? 2)
+    (copy_char_N cfg obj FSUnialpha 2)
+    tc_true).
+(* ·
+  inject_TM ? (move_to_end FSUnialpha L) 2 cfg ·
+  mmove cfg FSUnialpha 2 R. *)
+  
+definition R_cfg_to_obj ≝ λt1,t2:Vector (tape FSUnialpha) 3.
+  ∀c,ls.
+  nth cfg ? t1 (niltape ?) = mk_tape FSUnialpha (c::ls) (None ?) [ ] → 
+  (c = null → t2 = change_vec ?? t1 (midtape ? ls c [ ]) cfg) ∧
+  (c ≠ null → 
+   t2 = change_vec ??
+          (change_vec ?? t1
+             (midtape ? (left ? (nth obj ? t1 (niltape ?))) c (right ? (nth obj ? t1 (niltape ?)))) obj)
+          (midtape ? ls c [ ]) cfg).
+          
+lemma tape_move_mk_tape_L :
+  ∀sig,ls,c,rs.
+  (c = None ? → ls = [ ] ∨ rs = [ ]) → 
+  tape_move ? (mk_tape sig ls c rs) L =
+  mk_tape ? (tail ? ls) (option_hd ? ls) (option_cons ? c rs).
+#sig * [ * [ * | #c * ] | #l0 #ls0 * [ *
+[| #r0 #rs0 #H @False_ind cases (H (refl ??)) #H1 destruct (H1) ] | #c * ] ] 
+normalize //
+qed.
+
+lemma sem_cfg_to_obj : cfg_to_obj ⊨  R_cfg_to_obj.
+@(sem_seq_app FSUnialpha 2 ????? (sem_move_multi ? 2 cfg L ?)
+  (sem_if ??????????
+   (acc_sem_inject ?????? cfg ? sem_test_null_char)
+   (sem_nop …)
+   (sem_copy_char_N …)))
+// [@sym_not_eq //]
+#ta #tb *
+#tc * whd in ⊢ (%→?); #Htc *
+[ * #te * * * #Hcurtc #Hte1 #Hte2 whd in ⊢ (%→?); #Htb destruct (Htb)
+  #c #ls #Hta %
+  [ #Hc >Hta in Htc; >eq_mk_tape_rightof whd in match (tape_move ???); #Htc
+    cut (te = tc)
+    [ lapply (eq_vec_change_vec ??????? (sym_eq … Hte1) Hte2) >change_vec_same // ]
+      -Hte1 -Hte2 #Hte //
+    | #Hc >Hta in Htc; >eq_mk_tape_rightof whd in match (tape_move ???); #Htc
+      >Htc in Hcurtc; >nth_change_vec // normalize in ⊢ (%→?); 
+      #H destruct (H) @False_ind cases Hc /2/ ]
+| * #te * * * #Hcurtc #Hte1 #Hte2
+  whd in ⊢ (%→?); #Htb
+  #c #ls #Hta % #Hc
+  [ >Htc in Hcurtc; >Hta >nth_change_vec // 
+    normalize in ⊢ (%→?); * #H @False_ind /2/
+  | cut (te = tc)
+    [ lapply (eq_vec_change_vec ??????? (sym_eq … Hte1) Hte2)
+      >change_vec_same // ] -Hte1 -Hte2 #Hte destruct (Hte)
+    >Hta in Htc; whd in match (tape_move ???); #Htc
+    >Htc in Htb; >nth_change_vec // 
+    >nth_change_vec_neq [2:@eqb_false_to_not_eq //] >Hta 
+    #Htb @Htb
+  ]
+qed.
+
+definition char_to_move ≝ λc.match c with
+  [ bit b ⇒ if b then R else L
+  | _ ⇒ N].
+
+definition char_to_bit_option ≝ λc.match c with
+  [ bit b ⇒ Some ? (bit b)
+  | _ ⇒ None ?]. 
+
+definition R_cfg_to_obj1 ≝ λt1,t2:Vector (tape FSUnialpha) 3.
+  ∀c,ls.
+  nth cfg ? t1 (niltape ?) = mk_tape FSUnialpha (c::ls) (None ?) [ ] → 
+  c ≠ bar →
+  let new_obj ≝ 
+      tape_write ? (nth obj ? t1 (niltape ?)) (char_to_bit_option c) in
+    t2 = change_vec ??
+          (change_vec ?? t1
+            (tape_write ? (nth obj ? t1 (niltape ?)) (char_to_bit_option c)) obj)
+          (midtape ? ls c [ ]) cfg.
+
+lemma sem_cfg_to_obj1: cfg_to_obj ⊨  R_cfg_to_obj1.
+@(Realize_to_Realize … sem_cfg_to_obj) #t1 #t2 #H #c #ls #Hcfg #Hbar
+cases (H c ls Hcfg) cases (true_or_false (c==null)) #Hc
+  [#Ht2 #_ >(Ht2 (\P Hc)) -Ht2 @(eq_vec … (niltape ?))
+   #i #lei2 cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
+    [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
+      [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
+       >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+       >nth_change_vec_neq in ⊢ (???%); [2:@eqb_false_to_not_eq %]
+       >nth_change_vec // >(\P Hc) % 
+      |#Hi >Hi >nth_change_vec //
+      ] 
+    |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %] %
+    ]
+  |#_ #Ht2 >(Ht2 (\Pf Hc)) -Ht2 @(eq_vec … (niltape ?))
+   #i #lei2 cases (le_to_or_lt_eq … (le_S_S_to_le …lei2))
+    [#lei1 cases (le_to_or_lt_eq … (le_S_S_to_le …lei1))
+      [#lei0 lapply(le_n_O_to_eq … (le_S_S_to_le …lei0)) #eqi <eqi
+       >nth_change_vec_neq [2:@eqb_false_to_not_eq %] 
+       >nth_change_vec_neq in ⊢ (???%); [2:@eqb_false_to_not_eq %]
+       >nth_change_vec // >nth_change_vec // 
+       lapply (\bf Hbar) lapply Hc elim c //
+        [whd in ⊢ (??%?→?); #H destruct (H)
+        |#_ whd in ⊢ (??%?→?); #H destruct (H)
         ]
-      ]
+      |#Hi >Hi >nth_change_vec //
+      ] 
+    |#Hi >Hi >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %]
+     >nth_change_vec_neq [2:@eqb_false_to_not_eq %] %
     ]
   ]
 qed.
-     
- 
-lemma terminate_copy :  ∀src,dst,sig,n,t.
-  src ≠ dst → src < S n → dst < S n → copy src dst sig n ↓ t.
-#src #dst #sig #n #t #Hneq #Hsrc #Hdts
-@(terminate_while … (sem_copy_step …)) //
-<(change_vec_same … t src (niltape ?))
-cases (nth src (tape sig) t (niltape ?))
-[ % #t1 * #x * #y * * >nth_change_vec // normalize in ⊢ (%→?); #Hx destruct
-|2,3: #a0 #al0 % #t1 * #x * #y * * >nth_change_vec // normalize in ⊢ (%→?); #Hx destruct
-| #ls #c #rs lapply c -c lapply ls -ls lapply t -t elim rs
-  [#t #ls #c % #t1 * #x * #y * * >nth_change_vec // normalize in ⊢ (%→?);
-   #H1 destruct (H1) #_ >change_vec_change_vec #Ht1 % 
-   #t2 * #x0 * #y0 * * >Ht1 >nth_change_vec_neq [|@sym_not_eq //]
-   >nth_change_vec // normalize in ⊢ (%→?); #H destruct (H)
-  |#r0 #rs0 #IH #t #ls #c % #t1 * #x * #y * * >nth_change_vec //
-   normalize in ⊢ (%→?); #H destruct (H) #Hcur
-   >change_vec_change_vec >change_vec_commute // #Ht1 >Ht1 @IH
+       
+
+(* macchina che muove il nastro obj a destra o sinistra a seconda del valore
+   del current di prg, che codifica la direzione in cui ci muoviamo *)
+      
+definition tape_move_obj : mTM FSUnialpha 2 ≝ 
+  ifTM ?? 
+   (inject_TM ? (test_char ? (λc:FSUnialpha.c == bit false)) 2 prg)
+   (mmove obj FSUnialpha 2 L)
+   (ifTM ?? 
+    (inject_TM ? (test_char ? (λc:FSUnialpha.c == bit true)) 2 prg)
+    (mmove obj FSUnialpha 2 R)
+    (nop ??)
+    tc_true)
+   tc_true.
+
+definition R_tape_move_obj' ≝ λt1,t2:Vector (tape FSUnialpha) 3.
+  (current ? (nth prg ? t1 (niltape ?)) = Some ? (bit false) → 
+   t2 = change_vec ?? t1 (tape_move ? (nth obj ? t1 (niltape ?)) L) obj) ∧
+  (current ? (nth prg ? t1 (niltape ?)) = Some ? (bit true) → 
+   t2 = change_vec ?? t1 (tape_move ? (nth obj ? t1 (niltape ?)) R) obj) ∧
+  (current ? (nth prg ? t1 (niltape ?)) ≠ Some ? (bit false) →
+   current ? (nth prg ? t1 (niltape ?)) ≠ Some ? (bit true) →  
+   t2 = t1).
+   
+lemma sem_tape_move_obj' : tape_move_obj ⊨ R_tape_move_obj'.
+#ta cases (sem_if ??????????
+  (acc_sem_inject ?????? prg ? (sem_test_char ? (λc:FSUnialpha.c == bit false)))
+  (sem_move_multi ? 2 obj L ?)
+  (sem_if ??????????
+   (acc_sem_inject ?????? prg ? (sem_test_char ? (λc:FSUnialpha.c == bit true)))
+   (sem_move_multi ? 2 obj R ?)
+   (sem_nop …)) ta) //
+#i * #outc * #Hloop #HR %{i} %{outc} % [@Hloop] -i
+cases HR -HR
+[ * #tb * * * * #c * #Hcurta_prg #Hc lapply (\P Hc) -Hc #Hc #Htb1 #Htb2
+  whd in ⊢ (%→%); #Houtc >Houtc -Houtc % [ %
+  [ >Hcurta_prg #H destruct (H) >(?:tb = ta) 
+    [| lapply (eq_vec_change_vec ??????? Htb1 Htb2)
+       >change_vec_same // ] %
+  | >Hcurta_prg #H destruct (H) destruct (Hc) ]
+  | >Hcurta_prg >Hc * #H @False_ind /2/ ]
+| * #tb * * * #Hnotfalse #Htb1 #Htb2 cut (tb = ta) 
+  [ lapply (eq_vec_change_vec ??????? Htb1 Htb2)
+     >change_vec_same // ] -Htb1 -Htb2 #Htb destruct (Htb) *
+  [ * #tc * * * * #c * #Hcurta_prg #Hc lapply (\P Hc) -Hc #Hc #Htc1 #Htc2
+    whd in ⊢ (%→%); #Houtc >Houtc -Houtc % [ %
+    [ >Hcurta_prg #H destruct (H) destruct (Hc)
+    | >Hcurta_prg #H destruct (H) >(?:tc = ta) 
+      [| lapply (eq_vec_change_vec ??????? Htc1 Htc2)
+        >change_vec_same // ] % ]
+    | >Hcurta_prg >Hc #_ * #H @False_ind /2/ ]
+  | * #tc * * * #Hnottrue #Htc1 #Htc2 cut (tc = ta) 
+    [ lapply (eq_vec_change_vec ??????? Htc1 Htc2)
+      >change_vec_same // ] -Htc1 -Htc2 
+    #Htc destruct (Htc) whd in ⊢ (%→?); #Houtc % [ %
+    [ #Hcurta_prg lapply (\Pf (Hnotfalse ? Hcurta_prg)) * #H @False_ind /2/
+    | #Hcurta_prg lapply (\Pf (Hnottrue ? Hcurta_prg)) * #H @False_ind /2/ ]
+    | #_ #_ @Houtc ]
   ]
 ]
 qed.
 
-lemma sem_copy : ∀src,dst,sig,n.
-  src ≠ dst → src < S n → dst < S n → 
-  copy src dst sig n ⊨ R_copy src dst sig n.
-#i #j #sig #n #Hneq #Hi #Hj @WRealize_to_Realize [/2/| @wsem_copy // ]
+definition R_tape_move_obj ≝ λt1,t2:Vector (tape FSUnialpha) 3.
+  ∀c. current ? (nth prg ? t1 (niltape ?)) = Some ? c → 
+  t2 = change_vec ?? t1 (tape_move ? (nth obj ? t1 (niltape ?)) (char_to_move c)) obj.
+
+lemma sem_tape_move_obj : tape_move_obj ⊨ R_tape_move_obj.
+@(Realize_to_Realize … sem_tape_move_obj')
+#ta #tb * * #Htb1 #Htb2 #Htb3 * [ *
+[ @Htb2 | @Htb1 ] 
+| #Hcurta_prg change with (nth obj ? ta (niltape ?)) in match (tape_move ???);
+  >change_vec_same @Htb3 >Hcurta_prg % #H destruct (H)
+| #Hcurta_prg change with (nth obj ? ta (niltape ?)) in match (tape_move ???);
+  >change_vec_same @Htb3 >Hcurta_prg % #H destruct (H)
+]
+qed.
+
+(************** list of tape ******************)
+definition list_of_tape ≝ λsig.λt:tape sig.
+  reverse ? (left ? t)@option_cons ? (current ? t) (right ? t).
+
+lemma list_of_midtape: ∀sig,ls,c,rs.
+  list_of_tape sig (midtape ? ls c rs) = reverse ? ls@c::rs.
+// qed-.
+
+lemma list_of_rightof: ∀sig,ls,c.
+  list_of_tape sig (rightof ? c ls) = reverse ? (c::ls).
+#sig #ls #c <(append_nil ? (reverse ? (c::ls)))
+// qed-.
+
+lemma list_of_tape_move: ∀sig,t,m.
+  list_of_tape sig t = list_of_tape sig (tape_move ? t m).
+#sig #t * // cases t //
+ [(* rightof, move L *) #a #l >list_of_midtape 
+  >append_cons <reverse_single <reverse_append %
+ |(* midtape, move L *) * // 
+  #a #ls #c #rs >list_of_midtape >list_of_midtape
+  >reverse_cons >associative_append %
+ |(* midtape, move R *) #ls #c * 
+   [>list_of_midtape >list_of_rightof >reverse_cons %
+   |#a #rs >list_of_midtape >list_of_midtape >reverse_cons 
+    >associative_append %
+   ]
+ ]
+qed.
+
+lemma list_of_tape_write: ∀sig,cond,t,c. 
+(∀b. c = Some ? b → cond b =true) →
+(∀x. mem ? x (list_of_tape ? t) → cond x =true ) →
+∀x. mem ? x (list_of_tape sig (tape_write ? t c)) → cond x =true.
+#sig #cond #t #c #Hc #Htape #x lapply Hc cases c 
+  [(* c is None *) #_ whd in match (tape_write ???); @Htape
+  |#b #Hb lapply (Hb … (refl ??)) -Hb #Hb
+   whd in match (tape_write ???); >list_of_midtape
+   #Hx cases(mem_append ???? Hx) -Hx
+    [#Hx @Htape @mem_append_l1 @Hx
+    |* [//] 
+     #Hx @Htape @mem_append_l2 cases (current sig t)
+      [@Hx | #c1 %2 @Hx]
+    ]
+  ]
+qed.
+   
+lemma current_in_list: ∀sig,t,b. 
+  current sig t = Some ? b → mem ? b (list_of_tape sig t).
+#sig #t #b cases t
+  [whd in ⊢ (??%?→?); #Htmp destruct
+  |#l #b whd in ⊢ (??%?→?); #Htmp destruct
+  |#l #b whd in ⊢ (??%?→?); #Htmp destruct
+  |#ls #c #rs whd in ⊢ (??%?→?); #Htmp destruct
+   >list_of_midtape @mem_append_l2 % %
+  ]
+qed.
+  
+definition restart_tape ≝ λi,n. 
+  mmove i FSUnialpha n L ·
+  inject_TM ? (move_to_end FSUnialpha L) n i ·
+  mmove i FSUnialpha n R.
+  
+definition R_restart_tape ≝ λi,n.λint,outt:Vector (tape FSUnialpha) (S n).
+   ∀t.t = nth i ? int (niltape ?) → 
+   outt = change_vec ?? int 
+    (mk_tape ? [ ] (option_hd ? (list_of_tape ? t)) (tail ? (list_of_tape ? t))) i.
+
+lemma sem_restart_tape : ∀i,n.i < S n → restart_tape i n ⊨ R_restart_tape i n.
+#i #n #Hleq
+@(sem_seq_app ??????? (sem_move_multi ? n i L ?)
+  (sem_seq ?????? (sem_inject ???? i ? (sem_move_to_end_l ?))
+   (sem_move_multi ? n i R ?))) [1,2,3:@le_S_S_to_le //]
+#ta #tb * #tc * whd in ⊢ (%→?); #Htc
+* #td * * * #Htd1 #Htd2 #Htd3 
+whd in ⊢ (%→?); #Htb *
+[ #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
+  cut (td = tc) 
+  [ <(change_vec_same … tc … i … (niltape ?))
+    @(eq_vec_change_vec … (niltape ?))
+    [ @Htd1 >Htc >nth_change_vec //
+    | @Htd3 ] ]
+  (* >Htc in Htd1; >nth_change_vec // *) -Htd1 -Htd2 -Htd3
+  #Htd >Htd in Htb; >Htc >change_vec_change_vec >nth_change_vec //
+  #Htb >Htb %
+| #r0 #rs0 #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
+  cut (td = tc)
+  [ <(change_vec_same … tc … i … (niltape ?))
+    @(eq_vec_change_vec … (niltape ?))
+    [ @Htd1 >Htc >nth_change_vec //
+    | @Htd3 ] ]
+  (* >Htc in Htd1; >nth_change_vec // *) -Htd1 -Htd2 -Htd3
+  #Htd >Htd in Htb; >Htc >change_vec_change_vec >nth_change_vec //
+  #Htb >Htb %
+| #l0 #ls0 #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
+  cut (td = change_vec ?? tc (mk_tape ? [ ] (None ?) (reverse ? ls0@[l0])) i)
+  [ <(change_vec_same … tc … i … (niltape ?))
+    @(eq_vec_change_vec … (niltape ?))
+    [ @Htd2 >Htc >nth_change_vec //
+    | #j #Hij >nth_change_vec_neq // @Htd3 // ]]
+  #Htd >Htd in Htb; >Htc >change_vec_change_vec >change_vec_change_vec
+  >nth_change_vec // #Htb >Htb <(reverse_reverse ? ls0) in ⊢ (???%);
+  cases (reverse ? ls0)
+  [ %
+  | #l1 #ls1 >reverse_cons
+     >(?: list_of_tape ? (rightof ? l0 (reverse ? ls1@[l1])) =
+          l1::ls1@[l0])
+     [|change with (reverse ??@?) in ⊢ (??%?);
+       whd in match (left ??); >reverse_cons >reverse_append 
+       whd in ⊢ (??%?); @eq_f >reverse_reverse normalize >append_nil % ] % ]
+| * 
+  [ #c #rs #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
+    cut (td = tc) 
+    [ <(change_vec_same … tc … i … (niltape ?))
+    @(eq_vec_change_vec … (niltape ?))
+    [ @Htd1 >Htc >nth_change_vec //
+    | @Htd3 ] ]
+    (* >Htc in Htd1; >nth_change_vec // *) -Htd1 -Htd2 -Htd3
+    #Htd >Htd in Htb; >Htc >change_vec_change_vec >nth_change_vec //
+    #Htb >Htb %
+  | #l0 #ls0 #c #rs #Hta_i <Hta_i in Htc; whd in ⊢ (???(????%?)→?); #Htc
+    cut (td = change_vec ?? tc (mk_tape ? [ ] (None ?) (reverse ? ls0@l0::c::rs)) i)
+    [ @(eq_vec_change_vec … (niltape ?))
+      [ @Htd2 >Htc >nth_change_vec //
+      | @Htd3 ] ]
+    #Htd >Htd in Htb; >Htc >change_vec_change_vec >change_vec_change_vec
+    >nth_change_vec // #Htb >Htb <(reverse_reverse ? ls0) in ⊢ (???%);
+    cases (reverse ? ls0)
+    [ %
+    | #l1 #ls1 >reverse_cons
+      >(?: list_of_tape ? (midtape ? (l0::reverse ? ls1@[l1]) c rs) =
+            l1::ls1@l0::c::rs)
+      [|change with (reverse ??@?) in ⊢ (??%?);
+        whd in match (left ??); >reverse_cons >reverse_append 
+        whd in ⊢ (??%?); @eq_f >reverse_reverse normalize
+        >associative_append % ] % ]
+  ]
+]
 qed.