--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||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_ltpss.ma".
+include "Basic_2/reducibility/cpr.ma".
+include "Basic_2/reducibility/lcpr.ma".
+
+(* CONTEXT-SENSITIVE PARALLEL REDUCTION ON LOCAL ENVIRONMENTS *************)
+
+(* Advanced properties ****************************************************)
+
+lemma lcpr_pair: ∀L1,L2. L1 ⊢ ➡ L2 → ∀V1,V2. L2 ⊢ V1 ➡ V2 →
+ ∀I. L1. ⓑ{I} V1 ⊢ ➡ L2. ⓑ{I} V2.
+#L1 #L2 * #L #HL1 #HL2 #V1 #V2 *
+<(ltpss_fwd_length … HL2) /4 width=5/
+qed.