(* Forward lemmas with length for local environments ************************)
-lemma lsubr_fwd_length: ∀L1,L2. L1 ⫃ L2 → |L2| ≤ |L1|.
-#L1 #L2 #H elim H -L1 -L2 /2 width=1 by O, le_S_S/
+lemma lsubr_fwd_length: ∀L1,L2. L1 ⫃ L2 → |L2| = |L1|.
+#L1 #L2 #H elim H -L1 -L2 normalize //
qed-.