diff -r 6f1abe741fb6 -r 57c0b110b31e src/hugo/smart_graph.h
--- a/src/hugo/smart_graph.h	Tue Jul 20 09:52:03 2004 +0000
+++ b/src/hugo/smart_graph.h	Tue Jul 20 10:58:11 2004 +0000
@@ -136,21 +136,21 @@
 //     template< typename It >
 //     It first(Node v) const { It e; first(e,v); return e; }
 
-    bool valid(Edge e) const { return e.n!=-1; }
-    bool valid(Node n) const { return n.n!=-1; }
+    static bool valid(Edge e) { return e.n!=-1; }
+    static bool valid(Node n) { return n.n!=-1; }
     
     ///\deprecated Use
     ///\code
     ///  e=INVALID;
     ///\endcode
     ///instead.
-    void setInvalid(Edge &e) { e.n=-1; }
+    static void setInvalid(Edge &e) { e.n=-1; }
     ///\deprecated Use
     ///\code
     ///  e=INVALID;
     ///\endcode
     ///instead.
-    void setInvalid(Node &n) { n.n=-1; }
+    static void setInvalid(Node &n) { n.n=-1; }
     
     template <typename It> It getNext(It it) const
     { It tmp(it); return next(tmp); }
@@ -165,8 +165,8 @@
     { it.n=edges[it.n].next_in; return it; }
     EdgeIt& next(EdgeIt& it) const { --it.n; return it; }
 
-    int id(Node v) const { return v.n; }
-    int id(Edge e) const { return e.n; }
+    static int id(Node v) { return v.n; }
+    static int id(Edge e) { return e.n; }
 
     Node addNode() {
       Node n; n.n=nodes.size();
@@ -503,7 +503,7 @@
 
     ///Returns the oppositely directed
     ///pair of the edge \c e.
-    Edge opposite(Edge e) const
+    static Edge opposite(Edge e)
     {
       Edge f;
       f.idref() = e.idref() - 2*(e.idref()%2) + 1;