diff --git a/graph/AdjacencyListGraph.java b/graph/AdjacencyListGraph.java
index 30f6543..b9352f2 100644
--- a/graph/AdjacencyListGraph.java
+++ b/graph/AdjacencyListGraph.java
@@ -7,6 +7,12 @@ package graph;
  * Time: 16:30
  */
 
+import exceptions.InvalidPositionException;
+import map.HashTableMap;
+import position.NodePositionList;
+import position.Position;
+import position.PositionList;
+
 import java.util.Iterator;
 
 /**
@@ -15,7 +21,6 @@ import java.util.Iterator;
  * @author Roberto Tamassia, Eric Zamore
  */
 
-  /*
 public class AdjacencyListGraph<V,E> implements Graph<V,E> {
 
     protected NodePositionList<Vertex<V>> VList;	// container for vertices
@@ -179,8 +184,7 @@ public class AdjacencyListGraph<V,E> implements Graph<V,E> {
     }
 
     // Implementation of a decorable position by means of a hash table.
-    protected static class MyPosition<T>
-            extends HashTableMap<Object,Object> implements DecorablePosition<T> {
+    protected static class MyPosition<T>   extends HashTableMap<Object,Object> implements DecorablePosition<T> {
         // The element stored at this position.
         protected T elem;
         // Returns the element stored at this position.
@@ -223,8 +227,7 @@ public class AdjacencyListGraph<V,E> implements Graph<V,E> {
      //Implementation of a vertex for an undirected adjacency list
      //graph.  Each vertex stores its incidence container and position
      //in the vertex container of the graph.
-    protected  class MyVertex<V>
-            extends MyPosition<V> implements Vertex<V> {
+    protected  class MyVertex<V> extends MyPosition<V> implements Vertex<V> {
         // Incidence container of the vertex.
         protected PositionList<Edge<E>> incEdges;
         // Position of the vertex in the vertex container of the graph.
@@ -317,6 +320,4 @@ public class AdjacencyListGraph<V,E> implements Graph<V,E> {
                     "," + endVertices[1].toString() + ")";
         }
     }
-}
-
-*/
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/graph/DecorablePosition.java b/graph/DecorablePosition.java
new file mode 100644
index 0000000..50d4080
--- /dev/null
+++ b/graph/DecorablePosition.java
@@ -0,0 +1,15 @@
+package graph;
+
+import map.Map;
+import position.Position;
+
+/**
+ * An interface for a position that can be marked with an arbitrary
+ * number of decorations.
+ *
+ * @author Roberto Tamassia, Michael Goodrich
+ */
+
+public interface DecorablePosition<E>   extends Position<E>, Map<Object,Object> {}
+ // no new methods needed -- this is a mixture of Position and Map.
+
diff --git a/graph/DirectedGraph.java b/graph/DirectedGraph.java
new file mode 100644
index 0000000..a897db4
--- /dev/null
+++ b/graph/DirectedGraph.java
@@ -0,0 +1,12 @@
+package graph;
+
+/**
+ * Created with MONSTER.
+ * User: xgiovio
+ * Date: 20/05/2014
+ * Time: 19:59
+ */
+public interface DirectedGraph<V, E> extends  Graph<V,E>{
+    public boolean isDirected(Edge<E> e);
+    public Edge<E> insertDirectedEdge(Vertex<V> u, Vertex<V> v, V o);
+}
diff --git a/graph/Edge.java b/graph/Edge.java
new file mode 100644
index 0000000..eccc6ba
--- /dev/null
+++ b/graph/Edge.java
@@ -0,0 +1,6 @@
+package graph;
+/**
+ * An interface for an edge of a graph.
+ * @author Roberto Tamassia
+ */
+public interface Edge<E> extends DecorablePosition<E> { }
diff --git a/graph/Graph.java b/graph/Graph.java
new file mode 100644
index 0000000..2dcde31
--- /dev/null
+++ b/graph/Graph.java
@@ -0,0 +1,55 @@
+package graph;
+
+import exceptions.InvalidPositionException;
+
+/**
+ * An interface for a graph.
+ * @author Roberto Tamassia
+ */
+
+public interface Graph<V, E> {
+
+  /** Returns the number of vertices of the graph */
+  public int numVertices();
+
+  /** Returns the number of edges of the graph */
+  public int numEdges();
+
+  /** Returns the vertices of the graph as an iterable collection */
+  public Iterable<Vertex<V>> vertices();
+
+  /** Returns the edges of the graph as an iterable collection */
+  public Iterable<Edge<E>> edges();
+
+  /** Replaces the element of a given vertex with a new element and returns the old element */
+  public V replace(Vertex<V> p, V o) throws InvalidPositionException;
+
+  /** Replaces the element of a given edge with a new element and  returns the old element */
+  public E replace(Edge<E> p, E o) throws InvalidPositionException;
+
+  /** Returns the edges incident on a vertex as an iterable collection */
+  public Iterable<Edge<E>> incidentEdges(Vertex<V> v)   throws InvalidPositionException;
+
+  /** Returns the endvertices of a vertex as an array of length 2 */
+  public Vertex[] endVertices(Edge<E> e) throws InvalidPositionException;
+
+  /** Returns the other endvertex of an incident edge */
+  public Vertex<V> opposite(Vertex<V> v, Edge<E> e)  throws InvalidPositionException;
+
+  /** Tests whether two vertices are adjacent */
+  public boolean areAdjacent(Vertex<V> u, Vertex<V> v)  throws InvalidPositionException;
+
+  /** Inserts and return a new vertex with a given element */
+  public Vertex<V> insertVertex(V o);
+
+  /** Inserts and return a new edge with a given element between two  vertices */
+  public Edge<E> insertEdge(Vertex<V> u, Vertex<V> v, E o)  throws InvalidPositionException;
+
+  /** Removes a vertex and all its incident edges and returns the  element stored at the removed vertex */
+  public V removeVertex(Vertex<V> v) throws InvalidPositionException;
+
+  /** Removes an edge and return its element */
+  public E removeEdge(Edge<E> e) throws InvalidPositionException;
+}
+
+
diff --git a/graph/Vertex.java b/graph/Vertex.java
new file mode 100644
index 0000000..d3ef3d4
--- /dev/null
+++ b/graph/Vertex.java
@@ -0,0 +1,6 @@
+package graph;
+/**
+ * An interface for a vertex of a graph.
+ * @author Roberto Tamassia
+ */
+public interface Vertex<E> extends DecorablePosition<E> { }