diff --git a/lemon/bits/traits.h b/lemon/bits/traits.h
new file mode 100644
--- /dev/null
+++ b/lemon/bits/traits.h
@@ -0,0 +1,272 @@
+
+/* -*- C++ -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2003-2007
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef LEMON_BITS_TRAITS_H
+#define LEMON_BITS_TRAITS_H
+
+#include <lemon/bits/utility.h>
+
+///\file
+///\brief Traits for graphs and maps
+///
+
+namespace lemon {
+  template <typename _Graph, typename _Item>
+  class ItemSetTraits {};
+  
+
+  template <typename Graph, typename Enable = void>
+  struct NodeNotifierIndicator {
+    typedef InvalidType Type;
+  };
+  template <typename Graph>
+  struct NodeNotifierIndicator<
+    Graph, 
+    typename enable_if<typename Graph::NodeNotifier::Notifier, void>::type
+  > { 
+    typedef typename Graph::NodeNotifier Type;
+  };
+
+  template <typename _Graph>
+  class ItemSetTraits<_Graph, typename _Graph::Node> {
+  public:
+    
+    typedef _Graph Graph;
+
+    typedef typename Graph::Node Item;
+    typedef typename Graph::NodeIt ItemIt;
+
+    typedef typename NodeNotifierIndicator<Graph>::Type ItemNotifier;
+
+    template <typename _Value>
+    class Map : public Graph::template NodeMap<_Value> {
+    public:
+      typedef typename Graph::template NodeMap<_Value> Parent; 
+      typedef typename Graph::template NodeMap<_Value> Type; 
+      typedef typename Parent::Value Value;
+
+      Map(const Graph& _digraph) : Parent(_digraph) {}
+      Map(const Graph& _digraph, const Value& _value) 
+	: Parent(_digraph, _value) {}
+
+     };
+
+  };
+
+  template <typename Graph, typename Enable = void>
+  struct ArcNotifierIndicator {
+    typedef InvalidType Type;
+  };
+  template <typename Graph>
+  struct ArcNotifierIndicator<
+    Graph, 
+    typename enable_if<typename Graph::ArcNotifier::Notifier, void>::type
+  > { 
+    typedef typename Graph::ArcNotifier Type;
+  };
+
+  template <typename _Graph>
+  class ItemSetTraits<_Graph, typename _Graph::Arc> {
+  public:
+    
+    typedef _Graph Graph;
+
+    typedef typename Graph::Arc Item;
+    typedef typename Graph::ArcIt ItemIt;
+
+    typedef typename ArcNotifierIndicator<Graph>::Type ItemNotifier;
+
+    template <typename _Value>
+    class Map : public Graph::template ArcMap<_Value> {
+    public:
+      typedef typename Graph::template ArcMap<_Value> Parent; 
+      typedef typename Graph::template ArcMap<_Value> Type; 
+      typedef typename Parent::Value Value;
+
+      Map(const Graph& _digraph) : Parent(_digraph) {}
+      Map(const Graph& _digraph, const Value& _value) 
+	: Parent(_digraph, _value) {}
+    };
+
+  };
+
+  template <typename Graph, typename Enable = void>
+  struct EdgeNotifierIndicator {
+    typedef InvalidType Type;
+  };
+  template <typename Graph>
+  struct EdgeNotifierIndicator<
+    Graph, 
+    typename enable_if<typename Graph::EdgeNotifier::Notifier, void>::type
+  > { 
+    typedef typename Graph::EdgeNotifier Type;
+  };
+
+  template <typename _Graph>
+  class ItemSetTraits<_Graph, typename _Graph::Edge> {
+  public:
+    
+    typedef _Graph Graph;
+
+    typedef typename Graph::Edge Item;
+    typedef typename Graph::EdgeIt ItemIt;
+
+    typedef typename EdgeNotifierIndicator<Graph>::Type ItemNotifier;
+
+    template <typename _Value>
+    class Map : public Graph::template EdgeMap<_Value> {
+    public:
+      typedef typename Graph::template EdgeMap<_Value> Parent; 
+      typedef typename Graph::template EdgeMap<_Value> Type; 
+      typedef typename Parent::Value Value;
+
+      Map(const Graph& _digraph) : Parent(_digraph) {}
+      Map(const Graph& _digraph, const Value& _value) 
+	: Parent(_digraph, _value) {}
+    };
+
+  };
+
+  template <typename Map, typename Enable = void>
+  struct MapTraits {
+    typedef False ReferenceMapTag;
+
+    typedef typename Map::Key Key;
+    typedef typename Map::Value Value;
+
+    typedef const Value ConstReturnValue;
+    typedef const Value ReturnValue;
+  };
+
+  template <typename Map>
+  struct MapTraits<
+    Map, typename enable_if<typename Map::ReferenceMapTag, void>::type > 
+  {
+    typedef True ReferenceMapTag;
+    
+    typedef typename Map::Key Key;
+    typedef typename Map::Value Value;
+
+    typedef typename Map::ConstReference ConstReturnValue;
+    typedef typename Map::Reference ReturnValue;
+
+    typedef typename Map::ConstReference ConstReference; 
+    typedef typename Map::Reference Reference;
+ };
+
+  template <typename MatrixMap, typename Enable = void>
+  struct MatrixMapTraits {
+    typedef False ReferenceMapTag;
+
+    typedef typename MatrixMap::FirstKey FirstKey;
+    typedef typename MatrixMap::SecondKey SecondKey;
+    typedef typename MatrixMap::Value Value;
+
+    typedef const Value ConstReturnValue;
+    typedef const Value ReturnValue;
+  };
+
+  template <typename MatrixMap>
+  struct MatrixMapTraits<
+    MatrixMap, typename enable_if<typename MatrixMap::ReferenceMapTag, 
+                                  void>::type > 
+  {
+    typedef True ReferenceMapTag;
+    
+    typedef typename MatrixMap::FirstKey FirstKey;
+    typedef typename MatrixMap::SecondKey SecondKey;
+    typedef typename MatrixMap::Value Value;
+
+    typedef typename MatrixMap::ConstReference ConstReturnValue;
+    typedef typename MatrixMap::Reference ReturnValue;
+
+    typedef typename MatrixMap::ConstReference ConstReference; 
+    typedef typename MatrixMap::Reference Reference;
+ };
+
+  // Indicators for the tags
+
+  template <typename Graph, typename Enable = void>
+  struct NodeNumTagIndicator {
+    static const bool value = false;
+  };
+
+  template <typename Graph>
+  struct NodeNumTagIndicator<
+    Graph, 
+    typename enable_if<typename Graph::NodeNumTag, void>::type
+  > {
+    static const bool value = true;
+  };
+
+  template <typename Graph, typename Enable = void>
+  struct ArcNumTagIndicator {
+    static const bool value = false;
+  };
+
+  template <typename Graph>
+  struct ArcNumTagIndicator<
+    Graph, 
+    typename enable_if<typename Graph::ArcNumTag, void>::type
+  > {
+    static const bool value = true;
+  };
+
+  template <typename Graph, typename Enable = void>
+  struct FindArcTagIndicator {
+    static const bool value = false;
+  };
+
+  template <typename Graph>
+  struct FindArcTagIndicator<
+    Graph, 
+    typename enable_if<typename Graph::FindArcTag, void>::type
+  > {
+    static const bool value = true;
+  };
+
+  template <typename Graph, typename Enable = void>
+  struct UndirectedTagIndicator {
+    static const bool value = false;
+  };
+
+  template <typename Graph>
+  struct UndirectedTagIndicator<
+    Graph, 
+    typename enable_if<typename Graph::UndirectedTag, void>::type
+  > {
+    static const bool value = true;
+  };
+
+  template <typename Graph, typename Enable = void>
+  struct BuildTagIndicator {
+    static const bool value = false;
+  };
+
+  template <typename Graph>
+  struct BuildTagIndicator<
+    Graph, 
+    typename enable_if<typename Graph::BuildTag, void>::type
+  > {
+    static const bool value = true;
+  };
+
+}
+
+#endif