]> matita.cs.unibo.it Git - helm.git/blobdiff - matita/matita/contribs/lambdadelta/ground/lib/list_append.ma
update in ground
[helm.git] / matita / matita / contribs / lambdadelta / ground / lib / list_append.ma
index 042497aac144f4549933ebc96f4afc615c50218b..e4c3d743e2d17273430c19d9672a86fe3bd7a70c 100644 (file)
@@ -68,6 +68,15 @@ lemma eq_inv_list_empty_append (A):
 ]
 qed-.
 
+lemma eq_inv_list_append_empty (A):
+      ∀l1,l2. l1⨁{A}l2 = ⓔ →
+      ∧∧ l1 = ⓔ & l2 = ⓔ.
+#A *
+[ #l2 /2 width=1 by conj/
+| #a1 #l1 #l2 <list_append_lcons_sn #H destruct
+]
+qed-.
+
 (* Advanced inversions ******************************************************)
 
 lemma eq_inv_list_append_dx_sn_refl (A) (l1) (l2):