matita/matita/contribs/lambda_delta/basic_2/unfold/thin.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/unfold/ltpss.ma".
  16
  17 (* DELIFT ON LOCAL ENVIRONMENTS  ********************************************)
  18
  19 definition thin: nat → nat → relation lenv ≝
  20                  λd,e,L1,L2. ∃∃L. L1 [d, e] ▶* L & ⇩[d, e] L ≡ L2.
  21
  22 interpretation "delift (local environment)"
  23    'TSubst L1 d e L2 = (thin d e L1 L2).
  24
  25 (* Basic properties *********************************************************)