matita/matita/contribs/lambdadelta/static_2/syntax/bind_weight.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 "static_2/syntax/term_weight.ma".
  16 include "static_2/syntax/bind.ma".
  17
  18 (* WEIGHT OF A BINDER FOR LOCAL ENVIRONMENTS *******************************)
  19
  20 rec definition bw I ≝ match I with
  21 [ BUnit _   ⇒ 𝟏
  22 | BPair _ V ⇒ ♯❨V❩
  23 ].
  24
  25 interpretation
  26   "weight (binder for local environments)"
  27   'Weight I = (bw I).
  28
  29 (* Basic properties *********************************************************)
  30
  31 lemma bw_unit_unfold (I): 𝟏 = ♯❨BUnit I❩.
  32 // qed.
  33
  34 lemma bw_pair_unfold (I) (V): ♯❨V❩ = ♯❨BPair I V❩.
  35 // qed.