matita/matita/contribs/lambdadelta/delayed_updating/unwind/unwind2_preterm_eq.ma

   1 (**************************************************************************)
   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                             *)
   9 (*      \   /                                                             *)
  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  14
  15 include "delayed_updating/unwind/unwind2_prototerm.ma".
  16 include "delayed_updating/unwind/unwind2_path_append.ma".
  17 include "delayed_updating/syntax/preterm.ma".
  18 include "delayed_updating/syntax/path_structure_inner.ma".
  19 include "ground/lib/subset_equivalence.ma".
  20
  21 (* TAILED UNWIND FOR PRETERM ************************************************)
  22
  23 (* Constructions with subset_equivalence ************************************)
  24
  25 lemma unwind2_term_grafted_sn (f) (t) (p): p ϵ 𝐈 →
  26       ▼[▶[f]p](t⋔p) ⊆ (▼[f]t)⋔(⊗p).
  27 #f #t #p #Hp #q * #r #Hr #H0 destruct
  28 @(ex2_intro … Hr) -Hr
  29 <unwind2_path_append_inner_sn //
  30 qed-.
  31
  32 lemma unwind2_term_grafted_dx (f) (t) (p): p ϵ 𝐈 → p ϵ ▵t → t ϵ 𝐓 →
  33       (▼[f]t)⋔(⊗p) ⊆ ▼[▶[f]p](t⋔p).
  34 #f #t #p #H1p #H2p #Ht #q * #r #Hr #H0
  35 elim (unwind2_path_des_append_inner_sn … (sym_eq … H0)) -H0 //
  36 #p0 #q0 #Hp0 #Hq0 #H0 destruct
  37 >(Ht … Hp0) [|*: /2 width=2 by ex_intro/ ] -p
  38 /2 width=1 by in_comp_unwind2_path_term/
  39 qed-.
  40
  41 lemma unwind2_term_grafted (f) (t) (p): p ϵ 𝐈 → p ϵ ▵t → t ϵ 𝐓 →
  42       ▼[▶[f]p](t⋔p) ⇔ (▼[f]t)⋔(⊗p).
  43 /3 width=1 by unwind2_term_grafted_sn, unwind2_term_grafted_dx, conj/ qed.
  44
  45 lemma unwind2_term_grafted_S_dx (f) (t) (p): p ϵ ▵t → t ϵ 𝐓 →
  46       (▼[f]t)⋔((⊗p)◖𝗦) ⊆ ▼[▶[f]p](t⋔(p◖𝗦)).
  47 #f #t #p #Hp #Ht #q * #r #Hr
  48 >list_append_rcons_sn #H0
  49 elim (unwind2_path_inv_append_proper_dx … (sym_eq … H0)) -H0 //
  50 #p0 #q0 #Hp0 #Hq0 #H0 destruct
  51 >(Ht … Hp0) [|*: /2 width=2 by ex_intro/ ] -p
  52 elim (eq_inv_S_sn_unwind2_path … Hq0) -Hq0
  53 #r1 #r2 #Hr1 #Hr2 #H0 destruct
  54 lapply (preterm_in_root_append_inv_structure_empty_dx … p0 … Ht Hr1)
  55 [ /2 width=2 by ex_intro/ ] -Hr1 #Hr1 destruct
  56 /2 width=1 by in_comp_unwind2_path_term/
  57 qed-.
  58
  59 lemma unwind2_term_grafted_S (f) (t) (p): p ϵ ▵t → t ϵ 𝐓 →
  60       ▼[▶[f]p](t⋔(p◖𝗦)) ⇔ (▼[f]t)⋔((⊗p)◖𝗦).
  61 #f #t #p #Hp #Ht
  62 @conj
  63 [ >unwind2_rmap_S_dx >structure_S_dx
  64   @unwind2_term_grafted_sn // (**) (* auto fails *)
  65 | /2 width=1 by unwind2_term_grafted_S_dx/
  66 ]
  67 qed.