matita/matita/contribs/lambdadelta/delayed_updating/syntax/path.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/lib/list_rcons.ma".
  16 include "ground/notation/functions/element_e_0.ma".
  17 include "ground/notation/functions/black_circle_2.ma".
  18 include "ground/notation/functions/black_halfcircleright_2.ma".
  19 include "ground/notation/functions/black_halfcircleleft_2.ma".
  20 include "delayed_updating/syntax/label.ma".
  21
  22 (* PATH *********************************************************************)
  23
  24 (* Note: a path is a list of labels *)
  25 (* Note: constructed from the leaf (right end) to the root (left end) *)
  26 definition path ≝ list label.
  27
  28 interpretation
  29   "empty (paths)"
  30   'ElementE = (list_empty label).
  31
  32 interpretation
  33   "right cons (paths)"
  34   'BlackHalfCircleLeft p l = (list_lcons label l p).
  35
  36 interpretation
  37   "append (paths)"
  38   'BlackCircle p q = (list_append label q p).
  39
  40 interpretation
  41   "left cons (paths)"
  42   'BlackHalfCircleRight l p = (list_append label p (list_lcons label l (list_empty label))).