diff --git a/graph/AdjacencyListGraph.java b/graph/AdjacencyListGraph.java
new file mode 100644
index 0000000..895a1d1
--- /dev/null
+++ b/graph/AdjacencyListGraph.java
@@ -0,0 +1,320 @@
+package graph;
+
+/**
+ * Created with xgiovio.macbookair.
+ * User: xgiovio
+ * Date: 19/05/14
+ * Time: 16:30
+ */
+
+import java.util.Iterator;
+
+/**
+ * An realization of a graph according to adjacency list structure.
+ *
+ * @author Roberto Tamassia, Eric Zamore
+ */
+
+public class AdjacencyListGraph<V,E> implements Graph<V,E> {
+
+    protected NodePositionList<Vertex<V>> VList;	// container for vertices
+    protected NodePositionList<Edge<E>> EList;	// container for edges
+    /** Default constructor that creates an empty graph */
+    public AdjacencyListGraph() {
+        VList = new NodePositionList<Vertex<V>>();
+        EList = new NodePositionList<Edge<E>>();
+    }
+    /** Return an iterator over the vertices of the graph */
+    public Iterable<Vertex<V>> vertices() {
+        return VList;
+    }
+    /** Return an iterator over the edges of the graph */
+    public Iterable<Edge<E>> edges() {
+        return EList;
+    }
+    /** Replace the element a given position (vertex or edge) with a new
+     element and return the old element */
+    public Object replace(Position p, Object o)
+            throws InvalidPositionException {
+        MyPosition pp = checkPosition(p);
+        Object temp = p.element();
+        pp.setElement(o);
+        return temp;
+    }
+    /** Return an iterator over the edges incident on a vertex */
+    public Iterable<Edge<E>> incidentEdges(Vertex<V> v)
+            throws InvalidPositionException {
+        MyVertex<V> vv = checkVertex(v);
+        return vv.incidentEdges();
+
+    }
+    /** Return the endvertices of a edge in an array of length 2 */
+    public Vertex<V>[] endVertices(Edge<E> e)
+            throws InvalidPositionException {
+        MyEdge<E> ee = checkEdge(e);
+        return ee.endVertices();
+    }
+    /** Return the other endvertex of an incident edge */
+    public Vertex<V> opposite(Vertex<V> v, Edge<E> e)
+            throws InvalidPositionException {
+        checkVertex(v);
+        MyEdge<E> ee = checkEdge(e);
+        Vertex<V>[] endv = ee.endVertices();
+        if (v == endv[0])
+            return endv[1];
+        else if (v == endv[1])
+            return endv[0];
+        else
+            throw new InvalidPositionException("No such vertex exists");
+    }
+    /** Test whether two vertices are adjacent */
+    public boolean areAdjacent(Vertex<V> u, Vertex<V> v)
+            throws InvalidPositionException {
+        // search the incidence list of the vertex with smaller degree
+        Iterable<Edge<E>> iterToSearch;
+        if (degree(u) < degree(v)) {
+            iterToSearch = incidentEdges(u);
+        }
+        else {
+            iterToSearch = incidentEdges(v);
+        }
+        for (Edge<E> e: iterToSearch ) {
+            Vertex<V>[] endV = endVertices(e);
+            // if there exists an edge whose endpoints are u and v
+            if ((endV[0] == u && endV[1] == v) || (endV[0] == v && endV[1] == u))
+                return true;
+        }
+        return false;
+    }
+    /** Insert and return a new vertex with a given element */
+    public Vertex<V> insertVertex(V o) {
+        MyVertex<V> vv =  new MyVertex<V>(o);
+        VList.addLast(vv);
+        Position<Vertex<V>> p = VList.last();
+        vv.setLocation(p);
+        return vv;
+    }
+    /** Insert and return a new edge with a given element between two
+     vertices */
+    public Edge<E> insertEdge(Vertex<V> v, Vertex<V> w, E o)
+            throws InvalidPositionException {
+        MyVertex<V> vv = checkVertex(v);
+        MyVertex<V> ww = checkVertex(w);
+        MyEdge<E> ee = new MyEdge<E>(v, w, o);
+        Position<Edge<E>> pv = vv.insertIncidence(ee);
+        Position<Edge<E>> pw = ww.insertIncidence(ee);
+        ee.setIncidences(pv, pw);
+        EList.addLast(ee);
+        Position<Edge<E>> pe = EList.last();
+        ee.setLocation(pe);
+        return ee;
+    }
+    /** Remove a vertex and all its incident edges and return the
+     element stored at the removed vertex */
+    public V removeVertex(Vertex<V> v)
+            throws InvalidPositionException {
+        MyVertex<V> vv = checkVertex(v);
+        Iterator<Edge<E>> inc = incidentEdges(v).iterator();
+        while (inc.hasNext()) {
+            MyEdge<E> e = (MyEdge<E>) inc.next();
+            if (e.location() != null) // if the edge has not been marked invalid
+                removeEdge(e);
+        }
+        VList.remove(vv.location());
+        return v.element();
+    }
+    /** Remove an edge and return its element */
+    public E removeEdge(Edge<E> e)
+            throws InvalidPositionException {
+        MyEdge<E> ee = checkEdge(e);
+        MyVertex<V>[] endv = ee.endVertices();
+        Position<Edge<E>>[] inc = ee.incidences();
+        endv[0].removeIncidence(inc[0]);
+        endv[1].removeIncidence(inc[1]);
+        EList.remove(ee.location());
+        ee.setLocation(null);	// invalidating this edge
+        return e.element();
+    }
+
+    // Auxiliary methods
+
+    /** Return the degree of a given vertex */
+    public int degree(Vertex<V> v) {
+        MyVertex<V> vv = checkVertex(v);
+        return vv.degree();
+    }
+
+    /** Determines whether a given position is valid. */
+    protected MyPosition checkPosition(Position p)
+            throws InvalidPositionException {
+        if (p == null || !(p instanceof MyPosition))
+            throw new InvalidPositionException("Position is invalid");
+        return (MyPosition) p;
+    }
+
+    /** Determines whether a given vertex is valid. */
+    protected MyVertex<V> checkVertex(Vertex<V> v)
+            throws InvalidPositionException {
+        if (v == null || !(v instanceof MyVertex))
+            throw new InvalidPositionException("Vertex is invalid");
+        return (MyVertex<V>) v;
+    }
+
+    /** Determines whether a given edge is valid. */
+    protected MyEdge<E> checkEdge(Edge<E> e)
+            throws InvalidPositionException {
+        if (e == null || !(e instanceof MyEdge))
+            throw new InvalidPositionException("Edge is invalid");
+        return (MyEdge<E>) e;
+    }
+
+    /** Implementation of a decorable position by means of a hash
+     * table. */
+    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. */
+        public T element() {
+            return elem;
+        }
+        /** Sets the element stored at this position. */
+        public void setElement(T o) {
+            elem = o;
+        }
+    }
+
+    /** Returns a string representation of the vertex and edge lists,
+     * separated by a newline. */
+    public String toString() {
+        return VList.toString() + "\n" +  EList.toString();
+    }
+
+    public int numVertices() {
+        return VList.size();
+    }
+
+    public int numEdges() {
+        return EList.size();
+    }
+
+    public V replace(Vertex<V> p, V o) throws InvalidPositionException {
+        V temp = p.element();
+        MyVertex<V> vv = checkVertex(p);
+        vv.setElement(o);
+        return temp;
+    }
+
+    public E replace(Edge<E> p, E o) throws InvalidPositionException {
+        E temp = p.element();
+        MyEdge<E> ee = checkEdge(p);
+        ee.setElement(o);
+        return temp;
+    }
+
+    /** 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> {
+        /** Incidence container of the vertex. */
+        protected PositionList<Edge<E>> incEdges;
+        /** Position of the vertex in the vertex container of the graph. */
+        protected Position<Vertex<V>> loc;
+        /** Constructs the vertex with the given element. */
+        MyVertex(V o) {
+            elem = o;
+            incEdges = new NodePositionList<Edge<E>>();
+        }
+        /** Return the degree of a given vertex */
+        public int degree() {
+            return incEdges.size();
+        }
+        /** Returns the incident edges on this vertex. */
+        public Iterable<Edge<E>> incidentEdges() {
+            return incEdges;
+        }
+        /** Inserts an edge into the incidence container of this vertex. */
+        public Position<Edge<E>> insertIncidence(Edge<E> e) {
+            incEdges.addLast(e);
+            return incEdges.last();
+        }
+        /** Removes an edge from the incidence container of this vertex. */
+        public void removeIncidence(Position<Edge<E>> p) {
+            incEdges.remove(p);
+        }
+        /** Returns the position of this vertex in the vertex container of
+         * the graph. */
+        public Position<Vertex<V>> location() {
+            return loc;
+        }
+        /** Sets the position of this vertex in the vertex container of
+         * the graph. */
+        public void setLocation(Position<Vertex<V>> p) {
+            loc = p;
+        }
+        /** Returns a string representation of the element stored at this
+         * vertex. */
+        public String toString() {
+            return elem.toString();
+        }
+    }
+
+    /** Implementation of an edge for an undirected adjacency list
+     * graph.  Each edge stores its endpoints (end vertices), its
+     * positions within the incidence containers of its endpoints, and
+     * position in the edge container of the graph. */
+    protected class MyEdge<E> extends MyPosition<E> implements Edge<E> {
+
+        /** The end vertices of the edge. */
+        protected MyVertex<V>[] endVertices;
+        /** The positions of the entries for the edge in the incidence
+         * containers of the end vertices. */
+        protected Position<Edge<E>>[] Inc;
+        /** The position of the edge in the edge container of the
+         * graph. */
+        protected Position<Edge<E>> loc;
+
+        /** Constructs an edge with the given endpoints and elements. */
+        MyEdge (Vertex<V> v, Vertex<V> w, E o) {
+            elem = o;
+            endVertices = (MyVertex<V>[]) new MyVertex[2];
+            endVertices[0] = (MyVertex<V>)v;
+            endVertices[1] = (MyVertex<V>)w;
+            Inc = (Position<Edge<E>>[]) new Position[2];
+        }
+        /** Returns the end vertices of the edge. There are always two
+         * elements in the returned array. */
+        public MyVertex<V>[] endVertices() {
+            return endVertices;
+        }
+        /** Returns the positions of the edge in the incidence containers
+         * of its end vertices.  The returned array always contains two
+         * elements. */
+        public Position<Edge<E>>[] incidences() {
+            return Inc;
+        }
+        /** Sets the positions of the edge in the incidence containers of
+         * its end vertices. */
+        public void setIncidences(Position<Edge<E>> pv, Position<Edge<E>> pw) {
+            Inc[0] = pv;
+            Inc[1] = pw;
+        }
+        /** Returns the position of the edge in the edge container of the
+         * graph. */
+        public Position<Edge<E>> location() {
+            return loc;
+        }
+        /** Sets the position of the edge in the edge container of the
+         * graph. */
+        public void setLocation(Position<Edge<E>> p) {
+            loc = p;
+        }
+        /** Returns a string representation of the edge via a tuple of
+         * vertices. */
+        public String toString() {
+            return element() + "(" + endVertices[0].toString() +
+                    "," + endVertices[1].toString() + ")";
+        }
+    }
+}
\ No newline at end of file
diff --git a/partition/ListPartition.java b/partition/ListPartition.java
new file mode 100644
index 0000000..448e083
--- /dev/null
+++ b/partition/ListPartition.java
@@ -0,0 +1,39 @@
+package partition;
+
+import set.Set;
+
+/**
+ * Created with xgiovio.macbookair.
+ * User: xgiovio
+ * Date: 19/05/14
+ * Time: 15:02
+ */
+public class ListPartition <E> implements Partition<E> {
+
+
+
+    @Override
+    public int size() {
+        return 0;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return false;
+    }
+
+    @Override
+    public Set<E> makeSet(E x) {
+        return null;
+    }
+
+    @Override
+    public Set<E> union(Set<E> A, Set<E> B) {
+        return null;
+    }
+
+    @Override
+    public Set<E> find(E x) {
+        return null;
+    }
+}
diff --git a/partition/Partition.java b/partition/Partition.java
new file mode 100644
index 0000000..5260054
--- /dev/null
+++ b/partition/Partition.java
@@ -0,0 +1,26 @@
+package partition;
+
+import set.Set;
+
+/**
+ * Created with xgiovio.macbookair.
+ * User: xgiovio
+ * Date: 19/05/14
+ * Time: 14:24
+ */
+
+public interface Partition <E> {
+
+    public int size();
+    public boolean isEmpty();
+
+    // Restituisce l’insieme contenente il solo elemento x
+    public Set<E> makeSet(E x)   ;
+
+    // Restituisce l’unione di A e B, distruggendo i vecchi insiemi A e B
+    public Set <E>union(Set<E> A, Set<E> B) ;
+
+    // restituisce l’insieme che contiene l’elemento x
+    public Set <E> find(E x) ;
+
+}
\ No newline at end of file
diff --git a/set/OrderedListSet.java b/set/OrderedListSet.java
index 9db9606..bf5d8dd 100644
--- a/set/OrderedListSet.java
+++ b/set/OrderedListSet.java
@@ -40,6 +40,20 @@ public class OrderedListSet <E> implements Set<E> {
         c = in_c;
     }
 
+    public OrderedListSet(E in_e,Comparator<E> in_c ){
+        L = new NodePositionList<E>();
+        L.addLast(in_e);
+        c = in_c;
+    }
+
+    public OrderedListSet(E in_e){
+        L = new NodePositionList<E>();
+        L.addLast(in_e);
+        c = new DefaultComparator<E>();
+    }
+
+
+
 
 
 
@@ -83,6 +97,11 @@ public class OrderedListSet <E> implements Set<E> {
         return L.toString();
     }
 
+
+
+
+
+
     //////////////////////// inner class override methods from merge template /////
 
     protected class MergeUnion<E> extends MergeTemplate<E>{