matita/matita/contribs/lambdadelta/basic_2/syntax/genv_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 "basic_2/syntax/term_weight.ma".
  16 include "basic_2/syntax/genv.ma".
  17
  18 (* WEIGHT OF A GLOBAL ENVIRONMENT *******************************************)
  19
  20 rec definition gw G ≝ match G with
  21 [ GAtom       ⇒ 0
  22 | GPair G I T ⇒ gw G + ♯{T}
  23 ].
  24
  25 interpretation "weight (global environment)" 'Weight G = (gw G).
  26
  27 (* Basic properties *********************************************************)
  28
  29 lemma gw_pair: ∀I,G,T. ♯{G} < ♯{G.ⓑ{I}T}.
  30 normalize /2 width=1 by monotonic_le_plus_r/ qed.