Index: src/include/skeletons/maps.h
===================================================================
--- src/include/skeletons/maps.h	(revision 282)
+++ src/include/skeletons/maps.h	(revision 284)
@@ -11,27 +11,7 @@
   namespace skeleton {
   
-    /// Null map concept
-    template<typename K, typename T>
-    class NullMap
-    {
-    public:
-      /// Map's key type.
-      typedef K KeyType;    
-      /// Map's value type. (The type of objects associated with the keys).
-      typedef T ValueType;
-
-      /// Facility to define a map with an other value type
-      template<typename T1>
-      struct rebind {
-	/// The type of a map with the given value type
-	typedef NullMap<K,T1> other;
-      };
-
-      NullMap() {}
-    };
-    
     /// Readable map concept
     template<typename K, typename T>
-    class ReadableMap : public NullMap<K,T>
+    class ReadableMap
     {
     public:
@@ -49,15 +29,4 @@
       ReadableMap& operator=(const ReadableMap&) {return *this;}
 
-      /// Facility to define a map with an other value type (optional)
-      template<typename T1>
-      struct rebind {
-	/// The type of a map with the given value type
-	typedef ReadableMap<K,T1> other;
-      };
-      /// @brief Constructor that copies all keys from the other map and
-      /// assigns to them a default value (optional)
-      template<typename T1>
-      ReadableMap(const ReadableMap<K,T1> &map, const T1 &v) {}
-
       ReadableMap() {}
     };
@@ -66,5 +35,5 @@
     /// Writable map concept
     template<typename K, typename T>
-    class WritableMap : public NullMap<K,T>
+    class WritableMap
     {
     public:
@@ -76,20 +45,4 @@
       /// Sets the value associated with a key.
       void set(const KeyType &k,const ValueType &t) {}
-
-      /// Copy contsructor. (optional)
-      WritableMap(const WritableMap&) {}
-      /// Assignment operator. (optional)
-      WritableMap& operator=(const WritableMap&) {return *this;}
-
-      /// Facility to define a map with an other value type (optional)
-      template<typename T1>
-      struct rebind {
-	/// The type of a map with the given value type
-	typedef WritableMap<K,T1> other;
-      };
-      /// @brief Constructor that copies all keys from the other map and
-      /// assigns to them a default value (optional)
-      template<typename T1>
-      WritableMap(const WritableMap<K,T1> &map, const T1 &v) {}
 
       WritableMap() {}