matita/matita/contribs/lambdadelta/ground/relocation/gr_pat_lt.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 "ground/arith/pnat_pred.ma".
  16 include "ground/arith/pnat_lt.ma".
  17 include "ground/relocation/gr_pat.ma".
  18
  19 (* POSITIVE APPLICATION FOR GENERIC RELOCATION MAPS *************************)
  20
  21 (* Destructions with plt and ple ********************************************)
  22
  23 (*** at_increasing *)
  24 lemma gr_pat_increasing (i2) (i1) (f):
  25       @❪i1,f❫ ≘ i2 → i1 ≤ i2.
  26 #i2 elim i2 -i2
  27 [ #i1 #f #Hf elim (gr_pat_inv_unit_dx … Hf) -Hf //
  28 | #i2 #IH * //
  29   #i1 #f #Hf elim (gr_pat_inv_succ_bi … Hf) -Hf [1,4: * |*: // ]
  30   /3 width=2 by ple_succ_bi, ple_succ_dx/
  31 ]
  32 qed-.
  33
  34 (*** at_increasing_strict *)
  35 lemma gr_pat_increasing_strict (g) (i1) (i2):
  36       @❪i1,g❫ ≘ i2 → ∀f. ↑f = g →
  37       ∧∧ i1 < i2 & @❪i1,f❫ ≘ ↓i2.
  38 #g #i1 #i2 #Hg #f #H elim (gr_pat_inv_next … Hg … H) -Hg -H
  39 /4 width=2 by conj, gr_pat_increasing, ple_succ_bi/
  40 qed-.
  41
  42 (*** at_fwd_id_ex *)
  43 lemma gr_pat_des_id (f) (i): @❪i,f❫ ≘ i → ⫯⫰f = f.
  44 #f elim (gr_map_split_tl f) //
  45 #H #i #Hf elim (gr_pat_inv_next … Hf … H) -Hf -H
  46 #j2 #Hg #H destruct lapply (gr_pat_increasing … Hg) -Hg
  47 #H elim (plt_ge_false … H) -H //
  48 qed-.
  49
  50 (* Constructions with ple ***************************************************)
  51
  52 (*** at_le_ex *)
  53 lemma gr_pat_le_ex (j2) (i2) (f):
  54       @❪i2,f❫ ≘ j2 → ∀i1. i1 ≤ i2 →
  55       ∃∃j1. @❪i1,f❫ ≘ j1 & j1 ≤ j2.
  56 #j2 elim j2 -j2 [2: #j2 #IH ] #i2 #f #Hf
  57 [ elim (gr_pat_inv_succ_dx … Hf) -Hf [1,3: * |*: // ]
  58   #g [ #x2 ] #Hg [ #H2 ] #H0
  59   [ * /3 width=3 by gr_pat_refl, ex2_intro/
  60     #i1 #Hi12 destruct lapply (ple_inv_succ_bi … Hi12) -Hi12
  61     #Hi12 elim (IH … Hg … Hi12) -x2 -IH
  62     /3 width=7 by gr_pat_push, ex2_intro, ple_succ_bi/
  63   | #i1 #Hi12 elim (IH … Hg … Hi12) -IH -i2
  64     /3 width=5 by gr_pat_next, ex2_intro, ple_succ_bi/
  65   ]
  66 | elim (gr_pat_inv_unit_dx … Hf) -Hf //
  67   #g * -i2 #H2 #i1 #Hi12 <(ple_inv_unit_dx … Hi12)
  68   /3 width=3 by gr_pat_refl, ex2_intro/
  69 ]
  70 qed-.
  71
  72 (*** at_id_le *)
  73 lemma gr_pat_id_le (i1) (i2):
  74       i1 ≤ i2 → ∀f. @❪i2,f❫ ≘ i2 → @❪i1,f❫ ≘ i1.
  75 #i1 #i2 #H
  76 @(ple_ind_alt … H) -i1 -i2 [ #i2 | #i1 #i2 #_ #IH ] #f #Hf
  77 lapply (gr_pat_des_id … Hf) #H <H in Hf; -H
  78 /4 width=7 by gr_pat_inv_succ_push_succ, gr_pat_push, gr_pat_refl/
  79 qed-.