- lambda_delta: bug fix in static type assignment

[helm.git] / matita / matita / contribs / lambda_delta / basic_2 / unfold / thin.ma

diff --git a/matita/matita/contribs/lambda_delta/basic_2/unfold/thin.ma b/matita/matita/contribs/lambda_delta/basic_2/unfold/thin.ma
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+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||M||                                                             *)
+(*      ||A||       A project by Andrea Asperti                           *)
+(*      ||T||                                                             *)
+(*      ||I||       Developers:                                           *)
+(*      ||T||         The HELM team.                                      *)
+(*      ||A||         http://helm.cs.unibo.it                             *)
+(*      \   /                                                             *)
+(*       \ /        This file is distributed under the terms of the       *)
+(*        v         GNU General Public License Version 2                  *)
+(*                                                                        *)
+(**************************************************************************)
+
+include "basic_2/unfold/ltpss.ma".
+
+(* DELIFT ON LOCAL ENVIRONMENTS  ********************************************)
+
+definition thin: nat → nat → relation lenv ≝
+                 λd,e,L1,L2. ∃∃L. L1 [d, e] ▶* L & ⇩[d, e] L ≡ L2.
+
+interpretation "delift (local environment)"
+   'TSubst L1 d e L2 = (thin d e L1 L2).
+
+(* Basic properties *********************************************************)