matita/matita/contribs/lambda/pointer_sequence.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 "pointer_order.ma".
  16
  17 (* POINTER SEQUENCE *********************************************************)
  18
  19 (* Policy: pointer sequence metavariables: r, s *)
  20 definition pseq: Type[0] ≝ list ptr.
  21
  22 (* Note: a "head" computation contracts just redexes in the head *)
  23 definition is_head: predicate pseq ≝ All … in_head.
  24
  25 (* Note: to us, a "normal" computation contracts redexes in non-decreasing positions *)
  26 definition is_le: predicate pseq ≝ Allr … ple.