1.1 --- a/lemon/bits/edge_set_extender.h	Tue Dec 20 17:36:41 2011 +0100
     1.2 +++ b/lemon/bits/edge_set_extender.h	Tue Dec 20 17:38:19 2011 +0100
     1.3 @@ -280,6 +280,8 @@
     1.4  
     1.5      typedef EdgeSetExtender Graph;
     1.6  
     1.7 +    typedef True UndirectedTag;
     1.8 +
     1.9      typedef typename Parent::Node Node;
    1.10      typedef typename Parent::Arc Arc;
    1.11      typedef typename Parent::Edge Edge;