milestone update in ground_2 and basic_2A

[helm.git] / matita / matita / contribs / lambdadelta / basic_2A / etc / cpr / cprs_ltpr.etc

diff --git a/matita/matita/contribs/lambdadelta/basic_2A/etc/cpr/cprs_ltpr.etc b/matita/matita/contribs/lambdadelta/basic_2A/etc/cpr/cprs_ltpr.etc
new file mode 100644 (file)
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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_ltpr.ma".
+include "basic_2/computation/cprs.ma".
+
+(* CONTEXT-SENSITIVE PARALLEL COMPUTATION ON TERMS **************************)
+
+(* Properties concerning parallel unfold on terms ***************************)
+
+(* Basic_1: was only: pr3_subst1 *)
+lemma cprs_tpss_ltpr: ∀L1,T1,U1,d,e. L1 ⊢ T1 ▶* [d, e] U1 →
+                      ∀L2. L1 ➡ L2 → ∀T2. L2 ⊢ T1 ➡* T2 →
+                      ∃∃U2. L2 ⊢ U1 ➡* U2 & L2 ⊢ T2 ▶* [d, e] U2.
+#L1 #T1 #U1 #d #e #HTU1 #L2 #HL12 #T2 #HT12 elim HT12 -T2
+[ #T2 #HT12
+  elim (cpr_tpss_ltpr … HL12 … HT12 … HTU1) -L1 -T1 /3 width=3/
+| #T #T2 #_ #HT2 * #U #HU1 #HTU
+  elim (cpr_tpss_ltpr … HT2 … HTU) -L1 -T // /3 width=3/
+]
+qed.