matita/matita/contribs/lambdadelta/ground/relocation/gr_fcla.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/notation/relations/rfun_c_2.ma".
  16 include "ground/arith/nat_succ.ma".
  17 include "ground/relocation/gr_isi.ma".
  18
  19 (* FINITE COLENGTH ASSIGNMENT FOR GENERIC RELOCATION MAPS *******************)
  20
  21 (*** fcla *)
  22 inductive gr_fcla: relation2 gr_map nat ≝
  23 (*** fcla_isid *)
  24 | gr_fcla_isi (f): 𝐈❪f❫ → gr_fcla f (𝟎)
  25 (*** fcla_push *)
  26 | gr_fcla_push (f) (n): gr_fcla f n → gr_fcla (⫯f) n
  27 (*** fcla_next *)
  28 | gr_fcla_next (f) (n): gr_fcla f n → gr_fcla (↑f) (↑n)
  29 .
  30
  31 interpretation
  32   "finite colength assignment (generic relocation maps)"
  33   'RFunC f n = (gr_fcla f n).
  34
  35 (* Basic inversions *********************************************************)
  36
  37 (*** fcla_inv_px *)
  38 lemma gr_fcla_inv_push (g) (m): 𝐂❪g❫ ≘ m → ∀f. ⫯f = g → 𝐂❪f❫ ≘ m.
  39 #g #m * -g -m
  40 [ /3 width=3 by gr_fcla_isi, gr_isi_inv_push/
  41 | #g #m #Hg #f #H >(eq_inv_gr_push_bi … H) -f //
  42 | #g #m #_ #f #H elim (eq_inv_gr_push_next … H)
  43 ]
  44 qed-.
  45
  46 (*** fcla_inv_nx *)
  47 lemma gr_fcla_inv_next (g) (m): 𝐂❪g❫ ≘ m → ∀f. ↑f = g → ∃∃n. 𝐂❪f❫ ≘ n & ↑n = m.
  48 #g #m * -g -m
  49 [ #g #Hg #f #H destruct
  50   elim (gr_isi_inv_next … Hg) -Hg //
  51 | #g #m #_ #f #H elim (eq_inv_gr_next_push … H)
  52 | #g #m #Hg #f #H >(eq_inv_gr_next_bi …  H) -f
  53   /2 width=3 by ex2_intro/
  54 ]
  55 qed-.
  56
  57 (* Advanced inversions ******************************************************)
  58
  59 (*** cla_inv_nn *)
  60 lemma gr_cla_inv_next_succ (g) (m): 𝐂❪g❫ ≘ m → ∀f,n. ↑f = g → ↑n = m → 𝐂❪f❫ ≘ n.
  61 #g #m #H #f #n #H1 #H2 elim (gr_fcla_inv_next … H … H1) -g
  62 #x #Hf #H destruct <(eq_inv_nsucc_bi … H) -n //
  63 qed-.
  64
  65 (*** cla_inv_np *)
  66 lemma gr_cla_inv_next_zero (g) (m): 𝐂❪g❫ ≘ m → ∀f. ↑f = g → 𝟎 = m → ⊥.
  67 #g #m #H #f #H1 elim (gr_fcla_inv_next … H … H1) -g
  68 #x #_ #H1 #H2 destruct /2 width=2 by eq_inv_zero_nsucc/
  69 qed-.
  70
  71 (*** fcla_inv_xp *)
  72 lemma gr_fcla_inv_zero (g) (m): 𝐂❪g❫ ≘ m → 𝟎 = m → 𝐈❪g❫.
  73 #g #m #H elim H -g -m /3 width=3 by gr_isi_push/
  74 #g #m #_ #_ #H destruct elim (eq_inv_zero_nsucc … H)
  75 qed-.
  76
  77 (*** fcla_inv_isid *)
  78 lemma gr_fcla_inv_isi (g) (m): 𝐂❪g❫ ≘ m → 𝐈❪g❫ → 𝟎 = m.
  79 #f #n #H elim H -f -n /3 width=3 by gr_isi_inv_push/
  80 #f #n #_ #_ #H elim (gr_isi_inv_next … H) -H //
  81 qed-.