--- /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 "static_2/static/reqx_req.ma".
+include "basic_2/rt_transition/rpx_reqx.ma".
+include "basic_2/rt_transition/rpx_lpx.ma".
+
+(* UNBOUND PARALLEL RT-TRANSITION FOR FULL LOCAL ENVIRONMENTS ***************)
+
+(* Properties with sort-irrelevant equivalence for local environments *******)
+
+(* Basic_2A1: uses: lleq_lpx_trans *)
+lemma reqx_lpx_trans (h) (G): ∀L2,K2. ⦃G,L2⦄ ⊢ ⬈[h] K2 →
+ ∀L1. ∀T:term. L1 ≛[T] L2 →
+ ∃∃K1. ⦃G,L1⦄ ⊢ ⬈[h] K1 & K1 ≛[T] K2.
+#h #G #L2 #K2 #HLK2 #L1 #T #HL12
+lapply (lpx_rpx … T HLK2) -HLK2 #HLK2
+elim (reqx_rpx_trans … HLK2 … HL12) -L2 #K #H #HK2
+elim (rpx_inv_lpx_req … H) -H #K1 #HLK1 #HK1
+/3 width=5 by req_reqx_trans, ex2_intro/
+qed-.