update in ground and delayed_updating

[helm.git] / matita / matita / contribs / lambdadelta / delayed_updating / etc / dhd / path_dhd_structure.etc

diff --git a/matita/matita/contribs/lambdadelta/delayed_updating/etc/dhd/path_dhd_structure.etc b/matita/matita/contribs/lambdadelta/delayed_updating/etc/dhd/path_dhd_structure.etc
new file mode 100644 (file)
index 0000000..468d716
--- /dev/null
+++ b/matita/matita/contribs/lambdadelta/delayed_updating/etc/dhd/path_dhd_structure.etc
@@ -0,0 +1,34 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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/syntax/path_dhd.ma".
+include "delayed_updating/syntax/path_structure.ma".
+include "delayed_updating/syntax/path_depth.ma".
+
+(* HEAD BY DEPTH FOR PATH ***************************************************)
+
+(* Constructions with structure *********************************************)
+
+lemma path_dhd_structure_L_sn (p) (q):
+      let r ≝ 𝗟◗p in 
+      ⊗r = ↳⧣[♭⊗r]((⊗r)●q).
+#p elim p -p //
+* [ #n ] #p #IH #q //
+  [ <structure_L_sn //
+  | <structure_A_sn <list_append_lcons_sn 
+    <path_head_A_sn //
+  | <structure_S_sn //
+  ]
+]
+*)
\ No newline at end of file