matita/matita/contribs/lambda-delta/Basic-2/grammar/lenv_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/grammar/term_weight.ma".
  16 include "Basic-2/grammar/lenv.ma".
  17
  18 (* WEIGHTS ******************************************************************)
  19
  20 (* the weight of a local environment *)
  21 let rec lw L ≝ match L with
  22 [ LSort       ⇒ 0
  23 | LPair L _ V ⇒ lw L + #V
  24 ].
  25
  26 interpretation "weight (local environment)" 'Weight L = (lw L).
  27
  28 (* the weight of a closure *)
  29 definition cw: lenv → term → ? ≝ λL,T. #L + #T.
  30
  31 interpretation "weight (closure)" 'Weight L T = (cw L T).
  32
  33 axiom cw_wf_ind: ∀P:lenv→term→Prop.
  34                  (∀L2,T2. (∀L1,T1. #[L1,T1] < #[L2,T2] → P L1 T1) → P L2 T2) →
  35                  ∀L,T. P L T.