diff --git a/lemon/lgf_writer.h b/lemon/lgf_writer.h
new file mode 100644
--- /dev/null
+++ b/lemon/lgf_writer.h
@@ -0,0 +1,627 @@
+/* -*- C++ -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2003-2008
+ * 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.
+ *
+ */
+
+///\ingroup lemon_io
+///\file
+///\brief Lemon Graph Format writer.
+
+
+#ifndef LEMON_LGF_WRITER_H
+#define LEMON_LGF_WRITER_H
+
+#include <iostream>
+#include <fstream>
+#include <sstream>
+
+#include <algorithm>
+
+#include <vector>
+#include <functional>
+
+#include <lemon/assert.h>
+#include <lemon/graph_utils.h>
+
+namespace lemon {
+
+  namespace _writer_bits {
+
+    template <typename Value>
+    struct DefaultConverter {
+      std::string operator()(const Value& value) {
+	std::ostringstream os;
+	os << value;
+	return os.str();
+      }
+    };
+
+    template <typename T>
+    bool operator<(const T&, const T&) {
+      throw DataFormatError("Label map is not comparable");
+    }
+
+    template <typename _Map>
+    class MapLess {
+    public:
+      typedef _Map Map;
+      typedef typename Map::Key Item;
+
+    private:
+      const Map& _map;
+      
+    public:
+      MapLess(const Map& map) : _map(map) {}
+
+      bool operator()(const Item& left, const Item& right) {
+	return _map[left] < _map[right];
+      }
+    };
+
+    template <typename _Item>    
+    class MapStorageBase {
+    public:
+      typedef _Item Item;
+
+    public:
+      MapStorageBase() {}
+      virtual ~MapStorageBase() {}
+
+      virtual std::string get(const Item& item) = 0;
+      virtual void sort(std::vector<Item>&) = 0;
+    };
+
+    template <typename _Item, typename _Map, 
+	      typename _Converter = DefaultConverter<typename _Map::Value> >
+    class MapStorage : public MapStorageBase<_Item> {
+    public:
+      typedef _Map Map;
+      typedef _Converter Converter;
+      typedef _Item Item;
+      
+    private:
+      const Map& _map;
+      Converter _converter;
+
+    public:
+      MapStorage(const Map& map, const Converter& converter = Converter()) 
+	: _map(map), _converter(converter) {}
+      virtual ~MapStorage() {}
+
+      virtual std::string get(const Item& item) {
+	return _converter(_map[item]);
+      }
+      virtual void sort(std::vector<Item>& items) {
+	MapLess<Map> less(_map);
+	std::sort(items.begin(), items.end(), less);
+      }
+    };
+
+    class ValueStorageBase {
+    public:
+      ValueStorageBase() {}
+      virtual ~ValueStorageBase() {}
+
+      virtual std::string get() = 0;      
+    };
+
+    template <typename _Value, typename _Converter = DefaultConverter<_Value> >
+    class ValueStorage : public ValueStorageBase {
+    public:
+      typedef _Value Value;
+      typedef _Converter Converter;
+
+    private:
+      const Value& _value;
+      Converter _converter;
+
+    public:
+      ValueStorage(const Value& value, const Converter& converter = Converter())
+ 	: _value(value), _converter(converter) {}
+
+      virtual std::string get() {
+	return _converter(_value);
+      }
+    };
+
+    template <typename Value>
+    struct MapLookUpConverter {
+      const std::map<Value, std::string>& _map;
+      
+      MapLookUpConverter(const std::map<Value, std::string>& map) 
+	: _map(map) {}
+      
+      std::string operator()(const Value& str) {
+	typename std::map<Value, std::string>::const_iterator it = 
+	  _map.find(str);
+	if (it == _map.end()) {
+	  throw DataFormatError("Item not found");
+	}
+	return it->second;
+      }
+    };
+
+    bool isWhiteSpace(char c) {
+      return c == ' ' || c == '\t' || c == '\v' || 
+        c == '\n' || c == '\r' || c == '\f'; 
+    }
+
+    bool isEscaped(char c) {
+      return c == '\\' || c == '\"' || c == '\'' || 
+	c == '\a' || c == '\b';
+    }
+
+    static void writeEscape(std::ostream& os, char c) {
+      switch (c) {
+      case '\\':
+	os << "\\\\";
+	return;
+      case '\"':
+	os << "\\\"";
+	return;
+      case '\a':
+	os << "\\a";
+	return;
+      case '\b':
+	os << "\\b";
+	return;
+      case '\f':
+	os << "\\f";
+	return;
+      case '\r':
+	os << "\\r";
+	return;
+      case '\n':
+	os << "\\n";
+	return;
+      case '\t':
+	os << "\\t";
+	return;
+      case '\v':
+	os << "\\v";
+	return;
+      default:
+	if (c < 0x20) {
+	  os << '\\' << std::oct << static_cast<int>(c);
+	} else {
+	  os << c;
+	}
+	return;
+      }     
+    }
+
+    bool requireEscape(const std::string& str) {
+      std::istringstream is(str);
+      char c;
+      while (is.get(c)) {
+	if (isWhiteSpace(c) || isEscaped(c)) {
+	  return true;
+	}
+      }
+      return false;
+    }
+    
+    std::ostream& writeToken(std::ostream& os, const std::string& str) {
+
+      if (requireEscape(str)) {
+	os << '\"';
+	for (std::string::const_iterator it = str.begin(); 
+	     it != str.end(); ++it) {
+	  writeEscape(os, *it);
+	}	
+	os << '\"';
+      } else {
+	os << str;
+      }
+      return os;
+    }
+
+  }
+  
+  /// \e
+  template <typename _Digraph>
+  class DigraphWriter {
+  public:
+
+    typedef _Digraph Digraph;
+    GRAPH_TYPEDEFS(typename Digraph);
+    
+  private:
+
+
+    std::ostream* _os;
+    bool local_os;
+
+    Digraph& _digraph;
+
+    std::string _nodes_caption;
+    std::string _arcs_caption;
+    std::string _attributes_caption;
+    
+    typedef std::map<Node, std::string> NodeIndex;
+    NodeIndex _node_index;
+    typedef std::map<Arc, std::string> ArcIndex;
+    ArcIndex _arc_index;
+
+    typedef std::vector<std::pair<std::string, 
+      _writer_bits::MapStorageBase<Node>* > > NodeMaps;    
+    NodeMaps _node_maps; 
+
+    typedef std::vector<std::pair<std::string, 
+      _writer_bits::MapStorageBase<Arc>* > >ArcMaps;
+    ArcMaps _arc_maps;
+
+    typedef std::vector<std::pair<std::string, 
+      _writer_bits::ValueStorageBase*> > Attributes;
+    Attributes _attributes;
+
+    bool _skip_nodes;
+    bool _skip_arcs;
+
+  public:
+
+    /// \e
+    DigraphWriter(std::ostream& is, Digraph& digraph) 
+      : _os(&is), local_os(false), _digraph(digraph),
+	_skip_nodes(false), _skip_arcs(false) {}
+
+    /// \e
+    DigraphWriter(const std::string& fn, Digraph& digraph) 
+      : _os(new std::ofstream(fn.c_str())), local_os(true), _digraph(digraph),
+	_skip_nodes(false), _skip_arcs(false) {}
+
+    /// \e
+    DigraphWriter(const char* fn, Digraph& digraph) 
+      : _os(new std::ofstream(fn)), local_os(true), _digraph(digraph),
+	_skip_nodes(false), _skip_arcs(false) {}
+
+    DigraphWriter(DigraphWriter& other) 
+      : _os(other._os), local_os(other.local_os), _digraph(other._digraph),
+	_skip_nodes(other._skip_nodes), _skip_arcs(other._skip_arcs) {
+
+      other.is = 0;
+      other.local_os = false;
+
+      _node_index.swap(other._node_index);
+      _arc_index.swap(other._arc_index);
+
+      _node_maps.swap(other._node_maps);
+      _arc_maps.swap(other._arc_maps);
+      _attributes.swap(other._attributes);
+
+      _nodes_caption = other._nodes_caption;
+      _arcs_caption = other._arcs_caption;
+      _attributes_caption = other._attributes_caption;
+    }
+
+    /// \e
+    ~DigraphWriter() {
+      for (typename NodeMaps::iterator it = _node_maps.begin(); 
+	   it != _node_maps.end(); ++it) {
+	delete it->second;
+      }
+
+      for (typename ArcMaps::iterator it = _arc_maps.begin(); 
+	   it != _arc_maps.end(); ++it) {
+	delete it->second;
+      }
+
+      for (typename Attributes::iterator it = _attributes.begin(); 
+	   it != _attributes.end(); ++it) {
+	delete it->second;
+      }
+
+      if (local_os) {
+	delete _os;
+      }
+    }
+
+  private:
+    
+    DigraphWriter& operator=(const DigraphWriter&);
+
+  public:
+
+    /// \e
+    template <typename Map>
+    DigraphWriter& nodeMap(const std::string& caption, const Map& map) {
+      checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();
+      _writer_bits::MapStorageBase<Node>* storage = 
+	new _writer_bits::MapStorage<Node, Map>(map);
+      _node_maps.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    template <typename Map, typename Converter>
+    DigraphWriter& nodeMap(const std::string& caption, const Map& map, 
+			   const Converter& converter = Converter()) {
+      checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();
+      _writer_bits::MapStorageBase<Node>* storage = 
+	new _writer_bits::MapStorage<Node, Map, Converter>(map, converter);
+      _node_maps.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    template <typename Map>
+    DigraphWriter& arcMap(const std::string& caption, const Map& map) {
+      checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();
+      _writer_bits::MapStorageBase<Arc>* storage = 
+	new _writer_bits::MapStorage<Arc, Map>(map);
+      _arc_maps.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    template <typename Map, typename Converter>
+    DigraphWriter& arcMap(const std::string& caption, const Map& map, 
+			  const Converter& converter = Converter()) {
+      checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();
+      _writer_bits::MapStorageBase<Arc>* storage = 
+	new _writer_bits::MapStorage<Arc, Map, Converter>(map, converter);
+      _arc_maps.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    template <typename Value>
+    DigraphWriter& attribute(const std::string& caption, const Value& value) {
+      _writer_bits::ValueStorageBase* storage = 
+	new _writer_bits::ValueStorage<Value>(value);
+      _attributes.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    template <typename Value, typename Converter>
+    DigraphWriter& attribute(const std::string& caption, const Value& value, 
+			     const Converter& converter = Converter()) {
+      _writer_bits::ValueStorageBase* storage = 
+	new _writer_bits::ValueStorage<Value, Converter>(value, converter);
+      _attributes.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    DigraphWriter& node(const std::string& caption, const Node& node) {
+      typedef _writer_bits::MapLookUpConverter<Node> Converter;
+      Converter converter(_node_index);
+      _writer_bits::ValueStorageBase* storage = 
+	new _writer_bits::ValueStorage<Node, Converter>(node, converter);
+      _attributes.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    DigraphWriter& arc(const std::string& caption, const Arc& arc) {
+      typedef _writer_bits::MapLookUpConverter<Arc> Converter;
+      Converter converter(_arc_index);
+      _writer_bits::ValueStorageBase* storage = 
+	new _writer_bits::ValueStorage<Arc, Converter>(arc, converter);
+      _attributes.push_back(std::make_pair(caption, storage));
+      return *this;
+    }
+
+    /// \e
+    DigraphWriter& nodes(const std::string& caption) {
+      _nodes_caption = caption;
+      return *this;
+    }
+
+    /// \e
+    DigraphWriter& arcs(const std::string& caption) {
+      _arcs_caption = caption;
+      return *this;
+    }
+
+    /// \e
+    DigraphWriter& attributes(const std::string& caption) {
+      _attributes_caption = caption;
+      return *this;
+    }
+
+    DigraphWriter& skipNodes() {
+      LEMON_ASSERT(!_skip_nodes, "Multiple usage of skipNodes() member");
+      return *this;
+    }
+
+    DigraphWriter& skipArcs() {
+      LEMON_ASSERT(!_skip_arcs, "Multiple usage of skipArcs() member");
+      return *this;
+    }
+
+  private:
+
+    void writeNodes() {
+      _writer_bits::MapStorageBase<Node>* label = 0;
+      for (typename NodeMaps::iterator it = _node_maps.begin();
+	   it != _node_maps.end(); ++it) {
+        if (it->first == "label") {
+	  label = it->second;
+	  break;
+	}
+      }
+
+      *_os << "@nodes";
+      if (!_nodes_caption.empty()) {
+	*_os << ' ' << _nodes_caption;
+      }
+      *_os << std::endl;
+
+      if (label == 0) {
+	*_os << "label" << '\t';
+      }
+      for (typename NodeMaps::iterator it = _node_maps.begin();
+	   it != _node_maps.end(); ++it) {
+	*_os << it->first << '\t';
+      }
+      *_os << std::endl;
+
+      std::vector<Node> nodes;
+      for (NodeIt n(_digraph); n != INVALID; ++n) {
+	nodes.push_back(n);
+      }
+      
+      if (label == 0) {
+	IdMap<Digraph, Node> id_map(_digraph);
+	_writer_bits::MapLess<IdMap<Digraph, Node> > id_less(id_map);
+	std::sort(nodes.begin(), nodes.end(), id_less);
+      } else {
+	label->sort(nodes);
+      }
+
+      for (int i = 0; i < static_cast<int>(nodes.size()); ++i) {
+	Node n = nodes[i];
+	if (label == 0) {
+	  std::ostringstream os;
+	  os << _digraph.id(n);
+	  _writer_bits::writeToken(*_os, os.str());
+	  *_os << '\t';
+	  _node_index.insert(std::make_pair(n, os.str()));
+	}
+	for (typename NodeMaps::iterator it = _node_maps.begin();
+	     it != _node_maps.end(); ++it) {
+	  std::string value = it->second->get(n);
+	  _writer_bits::writeToken(*_os, value);
+	  if (it->first == "label") {
+	    _node_index.insert(std::make_pair(n, value));
+	  }
+	  *_os << '\t';
+	}
+	*_os << std::endl;
+      }
+    }
+
+    void writeArcs() {
+      _writer_bits::MapStorageBase<Arc>* label = 0;
+      for (typename ArcMaps::iterator it = _arc_maps.begin();
+	   it != _arc_maps.end(); ++it) {
+        if (it->first == "label") {
+	  label = it->second;
+	  break;
+	}
+      }
+
+      *_os << "@arcs";
+      if (!_arcs_caption.empty()) {
+	*_os << ' ' << _arcs_caption;
+      }
+      *_os << std::endl;
+
+      *_os << '\t' << '\t';
+      if (label == 0) {
+	*_os << "label" << '\t';
+      }
+      for (typename ArcMaps::iterator it = _arc_maps.begin();
+	   it != _arc_maps.end(); ++it) {
+	*_os << it->first << '\t';
+      }
+      *_os << std::endl;
+
+      std::vector<Arc> arcs;
+      for (ArcIt n(_digraph); n != INVALID; ++n) {
+	arcs.push_back(n);
+      }
+      
+      if (label == 0) {
+	IdMap<Digraph, Arc> id_map(_digraph);
+	_writer_bits::MapLess<IdMap<Digraph, Arc> > id_less(id_map);
+	std::sort(arcs.begin(), arcs.end(), id_less);
+      } else {
+	label->sort(arcs);
+      }
+
+      for (int i = 0; i < static_cast<int>(arcs.size()); ++i) {
+	Arc a = arcs[i];
+	_writer_bits::writeToken(*_os, _node_index.
+				 find(_digraph.source(a))->second);
+	*_os << '\t';
+	_writer_bits::writeToken(*_os, _node_index.
+				 find(_digraph.target(a))->second);
+	*_os << '\t';
+	if (label == 0) {
+	  std::ostringstream os;
+	  os << _digraph.id(a);
+	  _writer_bits::writeToken(*_os, os.str());
+	  *_os << '\t';
+	  _arc_index.insert(std::make_pair(a, os.str()));
+	}
+	for (typename ArcMaps::iterator it = _arc_maps.begin();
+	     it != _arc_maps.end(); ++it) {
+	  std::string value = it->second->get(a);
+	  _writer_bits::writeToken(*_os, value);
+	  if (it->first == "label") {
+	    _arc_index.insert(std::make_pair(a, value));
+	  }
+	  *_os << '\t';
+	}
+	*_os << std::endl;
+      }
+    }
+
+    void writeAttributes() {
+      if (_attributes.empty()) return;
+      *_os << "@attributes";
+      if (!_attributes_caption.empty()) {
+	*_os << ' ' << _attributes_caption;
+      }
+      *_os << std::endl;
+      for (typename Attributes::iterator it = _attributes.begin();
+	   it != _attributes.end(); ++it) {
+	*_os << it->first << ' ';
+	_writer_bits::writeToken(*_os, it->second->get());
+	*_os << std::endl;
+      }
+    }
+    
+  public:
+    
+    /// \e
+    void run() {
+      if (!_skip_nodes) {
+	writeNodes();
+      }
+      if (!_skip_arcs) {      
+	writeArcs();
+      }
+      writeAttributes();
+    }
+
+    /// \e
+    std::ostream& stream() {
+      return *_os;
+    }
+  };
+
+  template <typename Digraph>
+  DigraphWriter<Digraph> digraphWriter(std::istream& is, Digraph& digraph) {
+    return DigraphWriter<Digraph>(is, digraph);
+  }
+
+  template <typename Digraph>
+  DigraphWriter<Digraph> digraphWriter(const std::string& fn, 
+				       Digraph& digraph) {
+    return DigraphWriter<Digraph>(fn, digraph);
+  }
+
+  template <typename Digraph>
+  DigraphWriter<Digraph> digraphWriter(const char* fn, Digraph& digraph) {
+    return DigraphWriter<Digraph>(fn, digraph);
+  }
+}
+
+#endif