matita/matita/contribs/lambdadelta/delayed_updating/reduction/ifr_unwind.ma

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   2 (*       ___                                                              *)
   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
   6 (*      ||I||       Developers:                                           *)
   7 (*      ||T||         The HELM team.                                      *)
   8 (*      ||A||         http://helm.cs.unibo.it                             *)
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  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
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  13 (**************************************************************************)
  14
  15 include "delayed_updating/reduction/ifr.ma".
  16
  17 include "delayed_updating/unwind/unwind2_preterm_fsubst.ma".
  18 include "delayed_updating/unwind/unwind2_preterm_eq.ma".
  19 include "delayed_updating/unwind/unwind2_prototerm_lift.ma".
  20 include "delayed_updating/unwind/unwind2_rmap_head.ma".
  21
  22 include "delayed_updating/substitution/fsubst_eq.ma".
  23 include "delayed_updating/substitution/lift_prototerm_proper.ma".
  24 include "delayed_updating/substitution/lift_prototerm_eq.ma".
  25
  26 include "delayed_updating/syntax/path_head_structure.ma".
  27 include "delayed_updating/syntax/path_structure_depth.ma".
  28 include "delayed_updating/syntax/path_structure_reverse.ma".
  29 include "delayed_updating/syntax/path_depth_reverse.ma".
  30
  31 (* IMMEDIATE FOCUSED REDUCTION **********************************************)
  32
  33 (* Constructions with unwind ************************************************)
  34
  35 lemma ifr_unwind_bi (f) (p) (q) (t1) (t2):
  36       t1 ϵ 𝐓 → t1⋔(p◖𝗦) ϵ 𝐏 →
  37       t1 ➡𝐢𝐟[p,q] t2 → ▼[f]t1 ➡𝐢𝐟[⊗p,⊗q] ▼[f]t2.
  38 #f #p #q #t1 #t2 #H1t1 #H2t1
  39 * #n * #H1n #Ht1 #Ht2
  40 @(ex_intro … (↑♭q)) @and3_intro
  41 [ -H1t1 -H2t1 -Ht1 -Ht2
  42   >structure_L_sn >structure_reverse
  43   >H1n >path_head_structure_depth <H1n -H1n //
  44 | lapply (in_comp_unwind2_path_term f … Ht1) -Ht2 -Ht1 -H1t1 -H2t1
  45   <unwind2_path_d_dx
  46   >list_append_rcons_sn in H1n; <reverse_append #H1n
  47   lapply (unwind2_rmap_append_pap_closed f … H1n)
  48   <reverse_lcons <depth_L_dx #H2n
  49   lapply (eq_inv_ninj_bi … H2n) -H2n #H2n <H2n -H2n -H1n #Ht1 //
  50 | lapply (unwind2_term_eq_repl_dx f … Ht2) -Ht2 #Ht2
  51   @(subset_eq_trans … Ht2) -t2
  52   @(subset_eq_trans … (unwind2_term_fsubst …))
  53   [ @fsubst_eq_repl [ // | // ]
  54     @(subset_eq_canc_sn … (lift_term_eq_repl_dx …))
  55     [ @unwind2_term_grafted_S /2 width=2 by ex_intro/ | skip ] -Ht1
  56     @(subset_eq_trans … (lift_unwind2_term_after …))
  57     @(subset_eq_canc_dx … (unwind2_term_after_lift …))
  58     @unwind2_term_eq_repl_sn
  59 (* Note: crux of the proof begins *)
  60     >list_append_rcons_sn in H1n; <reverse_append #H1n
  61     @(stream_eq_trans … (tr_compose_uni_dx …))
  62     @tr_compose_eq_repl
  63     [ <unwind2_rmap_append_pap_closed //
  64     | >unwind2_rmap_A_sn <reverse_rcons
  65       /2 width=1 by tls_unwind2_rmap_append_closed/
  66     ]
  67 (* Note: crux of the proof ends *)
  68   | //
  69   | /2 width=2 by ex_intro/
  70   | /2 width=6 by lift_term_proper/
  71   ]
  72 ]
  73 qed.