update in basic_2 ...

[helm.git] / helm / software / matita / nlibrary / datatypes / list-theory.ma

diff --git a/helm/software/matita/nlibrary/datatypes/list-theory.ma b/helm/software/matita/nlibrary/datatypes/list-theory.ma
index 14bab26e31558989a2fa8ef3075138d1bf4b8977..4957feed26ac57e4c219b740eab7dd85f79ff3d2 100644 (file)
--- a/helm/software/matita/nlibrary/datatypes/list-theory.ma
+++ b/helm/software/matita/nlibrary/datatypes/list-theory.ma
@@ -20,7 +20,7 @@ ntheorem nil_cons:
 #A;#l;#a; @; #H; ndestruct;
 nqed.
 
-ntheorem append_nil: ∀A:Type.∀l:list A.l @ □ = l.
+ntheorem append_nil: ∀A:Type.∀l:list A.l @ [ ] = l.
 #A;#l;nelim l;//;
 #a;#l1;#IH;nnormalize;//;
 nqed.