--- /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/computation/cpxs_llpx.ma".
+include "basic_2/computation/csx_alt.ma".
+
+(* CONTEXT-SENSITIVE EXTENDED STRONGLY NORMALIZING TERMS ********************)
+
+(* Properties on lazy sn extended reduction for local environments **********)
+
+lemma csx_llpx_conf: ∀h,g,G,L1,T. ⦃G, L1⦄ ⊢ ⬊*[h, g] T →
+ ∀L2. ⦃G, L1⦄ ⊢ ➡[h, g, T, 0] L2 → ⦃G, L2⦄ ⊢ ⬊*[h, g] T.
+#h #g #G #L1 #T #H @(csx_ind_alt … H) -T
+/5 width=3 by csx_intro_cpxs, llpx_cpxs_trans, cpxs_llpx_conf/ (* 2 cpxs_llpx_trans *)
+qed-.