diff --git a/src/Expression.java b/src/Expression.java
index a771582..6ad25ad 100644
--- a/src/Expression.java
+++ b/src/Expression.java
@@ -121,7 +121,7 @@ public class Expression {
         e.negExpressionPrefixe();
         System.out.println(e.getExpressionPrefixe());
         System.out.println();
-        
+
         Tree t = new Tree(e.getExpressionPrefixe());
         t.display();
     }
diff --git a/src/Node.java b/src/Node.java
index d5edb1c..edd5e62 100644
--- a/src/Node.java
+++ b/src/Node.java
@@ -10,6 +10,8 @@ public class Node {
     private Node rigthChild;
     private int lvl;
 
+    private int pos = 0;
+
     Node(Node father, Node leftChild, Node rightChild, char name, int lvl){
         this.node = name;
         this.father = father;
@@ -40,4 +42,20 @@ public class Node {
     public Node getRigthChild() {
         return rigthChild;
     }
+
+    public char getNode() {
+        return node;
+    }
+
+    public Node getFather() {
+        return father;
+    }
+
+    public int getPos() {
+        return pos;
+    }
+
+    public void setPos(int pos) {
+        this.pos = pos;
+    }
 }
diff --git a/src/Tree.java b/src/Tree.java
index cc65bad..a712e81 100644
--- a/src/Tree.java
+++ b/src/Tree.java
@@ -9,6 +9,8 @@ public class Tree {
     Tree (String exp){
         this.exp = exp;
         root = tree(0);
+        display();
+        findPatern(root);
     }
 
     private Node tree(int pos) {
@@ -18,12 +20,15 @@ public class Tree {
             if (item == '!'){
                 Node fils = tree(pos+1);
                 Node f =  new Node(null, fils, null, item, 1+fils.getLvl());
+                fils.setPos(1);
                 fils.setFather(f);
                 return f;
             } else {
                 Node filsG = tree(pos+1);
                 Node filsD = tree(pos+filsG.getLvl()+1);
                 Node f = new Node(null, filsG, filsD, item, filsG.getLvl() + filsD.getLvl()+1);
+                filsG.setPos(1);
+                filsD.setPos(2);
                 filsG.setFather(f);
                 filsD.setFather(f);
                 return f;
@@ -37,7 +42,7 @@ public class Tree {
         displayNode(root,0);
     }
 
-    private void displayNode(Node n, int lvl){
+    private void displayNode(Node n, int lvl) {
         for (int i = 0; i < lvl; i++)
             System.out.print("-");
 
@@ -47,4 +52,100 @@ public class Tree {
         if (n.getRigthChild() != null)
             displayNode(n.getRigthChild(),lvl+1);
     }
-}
+
+    private void findPatern (Node node) {
+        if (replacePatern(node)){
+            if (node.getFather() == null)
+                findPatern(root);
+            else
+                findPatern(node.getFather());
+        } else {
+            if( node.getLeftChild() != null)
+                findPatern(node.getLeftChild());
+            if( node.getRigthChild() != null)
+                findPatern(node.getRigthChild());
+        }
+    }
+
+    private boolean replacePatern (Node father) {
+        Node leftChild = father.getLeftChild();
+        Node rightChild = father.getRigthChild();
+        switch (father.getNode()) {
+            case '!' :
+                Node child = leftChild.getLeftChild();
+                switch (leftChild.getNode()){
+                    case '!':
+
+                        appliedGreatFather(father, child);
+                        break;
+                    case '|' :
+                        Node lc = child.getLeftChild();
+                        Node rc = child.getRigthChild();
+
+                        Node notlc = new Node(null,lc,null,'!', lc.getLvl() +1);
+                        Node notrc = new Node(null,rc,null,'!', rc.getLvl() +1);
+                        lc.setFather(notlc);
+                        rc.setFather(notrc);
+
+                        Node greatfather = new Node(father.getFather(),notlc,notrc,'&',notlc.getLvl() + notrc.getLvl() +1);
+                        notlc.setFather(greatfather);
+                        notrc.setFather(greatfather);
+                        appliedGreatFather(father, greatfather);
+                        break;
+                    case '&' :
+                        Node lc_2 = child.getLeftChild();
+                        Node rc_2 = child.getRigthChild();
+
+                        Node notlc_2 = new Node(null,lc_2,null,'!', lc_2.getLvl() +1);
+                        Node notrc_2 = new Node(null,rc_2,null,'!', rc_2.getLvl() +1);
+                        lc_2.setFather(notlc_2);
+                        rc_2.setFather(notrc_2);
+
+                        Node greatfather_2 = new Node(father.getFather(),notlc_2,notrc_2,'|',notlc_2.getLvl() + notrc_2.getLvl() +1);
+                        notlc_2.setFather(greatfather_2);
+                        notrc_2.setFather(greatfather_2);
+                        appliedGreatFather(father, greatfather_2);
+                        break;
+                    case '>' :
+                        Node lc_3 = child.getLeftChild();
+                        Node rc_3 = child.getRigthChild();
+
+                        Node notrc_3 = new Node(null,rc_3,null,'!', rc_3.getLvl() +1);
+                        rc_3.setFather(notrc_3);
+
+                        Node greatfather_3 = new Node(father.getFather(),lc_3,notrc_3,'&',lc_3.getLvl() + notrc_3.getLvl() +1);
+                        lc_3.setFather(greatfather_3);
+                        notrc_3.setFather(greatfather_3);
+
+                        appliedGreatFather(father, greatfather_3);
+                        break;
+                    default:
+                        return false;
+                }
+                break;
+            case '>' :
+                Node notlc = new Node(null,leftChild,null,'!', leftChild.getLvl() +1);
+                leftChild.setFather(notlc);
+
+                Node greatfather = new Node(father.getFather(),notlc,rightChild,'|',notlc.getLvl() + rightChild.getLvl() +1);
+                notlc.setFather(greatfather);
+                rightChild.setFather(greatfather);
+                appliedGreatFather(father, greatfather);
+                break;
+            default:
+                return false;
+        }
+        return true;
+    }
+
+    private void appliedGreatFather (Node father, Node greatFather) {
+        if (father.getPos() == 1) {
+            father.getFather().setLeftChild(greatFather);
+            greatFather.setFather(father);
+        } else if (father.getPos() == 2) {
+            father.getFather().setRigthChild(greatFather);
+            greatFather.setFather(father);
+        } else
+            root = greatFather;
+    }
+}
\ No newline at end of file