- lib: some additions

[helm.git] / matita / matita / contribs / lambda_delta / basic_2 / computation / cprs_delift.ma

diff --git a/matita/matita/contribs/lambda_delta/basic_2/computation/cprs_delift.ma b/matita/matita/contribs/lambda_delta/basic_2/computation/cprs_delift.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/reducibility/cpr_delift.ma".
+include "basic_2/computation/cprs.ma".
+
+(* CONTEXT-SENSITIVE PARALLEL COMPUTATION ON TERMS **************************)
+
+(* Properties on inverse basic term relocation ******************************)
+
+(* Basic_1: was only: pr3_gen_cabbr *)
+lemma thin_cprs_delift_conf: ∀L,U1,U2. L ⊢ U1 ➡* U2 →
+                             ∀K,d,e. L [d, e] ≡ K → ∀T1. L ⊢ U1 [d, e] ≡ T1 →
+                             ∃∃T2. K ⊢ T1 ➡* T2 & L ⊢ U2 [d, e] ≡ T2.
+#L #U1 #U2 #H @(cprs_ind … H) -U2 /2 width=3/
+#U #U2 #_ #HU2 #IHU1 #K #d #e #HLK #T1 #HTU1
+elim (IHU1 … HLK … HTU1) -U1 #T #HT1 #HUT
+elim (thin_cpr_delift_conf … HU2 … HLK … HUT) -U -HLK /3 width=3/
+qed.