--- /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 "delayed_updating/unwind/unwind2_path_structure.ma".
+include "delayed_updating/syntax/path_inner.ma".
+
+(* UNWIND FOR PATH **********************************************************)
+
+(* Destructions with inner condition for path *******************************)
+
+lemma unwind2_path_des_inner (f) (p):
+ ▼[f]p ϵ 𝐈 → p ϵ 𝐈.
+#f #p @(list_ind_rcons … p) -p //
+#p * [ #n ] #_ //
+<unwind2_path_d_dx #H0
+elim (pic_inv_d_dx … H0)
+qed-.