--- /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/relocation/lexs_length.ma".
+include "basic_2/relocation/lex.ma".
+
+(* GENERIC EXTENSION OF A CONTEXT-SENSITIVE REALTION FOR TERMS **************)
+
+(* Forward lemmas with length for local environments ************************)
+
+(* Basic_2A1: was: lpx_sn_fwd_length *)
+lemma lex_fwd_length: ∀R,L1,L2. L1 ⪤[R] L2 → |L1| = |L2|.
+#R #L1 #L2 * /2 width=4 by lexs_fwd_length/
+qed-.