diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.2.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.2.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.2.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.3.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.3.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.3.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.4.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.4.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.4.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.5.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.5.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.5.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.6.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.6.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.6.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.7.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.7.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.7.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.8.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.8.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.8.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.9.crc b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.9.crc
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/.9.crc
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/2 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/2
new file mode 100755
index 0000000..f8bec75
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/2
@@ -0,0 +1,2 @@
+ATA	{[(1-2_1)]	[]	[]	[]	[]	AATA}
+AAT	{[(1-1_1)]	[]	[]	[]	[]	AATA}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/3 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/3
new file mode 100755
index 0000000..0f3d880
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/3
@@ -0,0 +1 @@
+ATA	{[(1-2_1)]	[]	[]	[]	[]	AATAG}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/4 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/4
new file mode 100755
index 0000000..91211fc
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/4
@@ -0,0 +1,2 @@
+CTA	{[(1-3_1)]	[]	[]	[]	[]	TCTATT}
+ATA	{[(1-2_1)]	[]	[]	[]	[]	AATAGA}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/5 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/5
new file mode 100755
index 0000000..a2ae06f
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/5
@@ -0,0 +1,2 @@
+ATA	{[(1-2_1)]	[]	[]	[]	[]	AATAGAA}
+AGA	{[(1-4_1)]	[]	[]	[]	[]	AATAGAA}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/6 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/6
new file mode 100755
index 0000000..c084bee
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/6
@@ -0,0 +1,2 @@
+CTA	{[(1-3_1)]	[]	[]	[]	[]	GTTCTATT}
+AGA	{[(1-4_1)]	[]	[]	[]	[]	AATAGAAC}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/7 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/7
new file mode 100755
index 0000000..30b31af
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/7
@@ -0,0 +1 @@
+AGA	{[(1-4_1)]	[]	[]	[]	[]	AATAGAACT}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/8 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/8
new file mode 100755
index 0000000..900707b
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/8
@@ -0,0 +1,2 @@
+GAA	{[(1-5_1)]	[]	[]	[]	[]	AATAGAACTT}
+AGA	{[(1-4_1)]	[]	[]	[]	[]	AATAGAACTT}
diff --git a/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/9 b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/9
new file mode 100755
index 0000000..862bc7c4
--- /dev/null
+++ b/genomix/genomix-pregelix/data/LogAlgorithmForMergeGraph/txt/9
@@ -0,0 +1,2 @@
+AGA	{[(1-4_1)]	[]	[]	[]	[]	AATAGAACTTA}
+AAC	{[(1-6_1)]	[]	[]	[]	[]	AATAGAACTTA}
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/VertexValueWritable.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/VertexValueWritable.java
index 48a9f52..f1ed1ad 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/VertexValueWritable.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/VertexValueWritable.java
@@ -11,7 +11,18 @@
 
 public class VertexValueWritable implements WritableComparable<VertexValueWritable> {
 
-    public static class VertexStateFlag {
+    public static class State extends VertexStateFlag{
+        public static final byte HEAD_SHOULD_MERGEWITHPREV = 0b101 << 0;
+        public static final byte HEAD_SHOULD_MERGEWITHNEXT = 0b111 << 0;
+            
+        public static final byte NO_MERGE = 0b00 << 3;
+        public static final byte SHOULD_MERGEWITHNEXT = 0b01 << 3;
+        public static final byte SHOULD_MERGEWITHPREV = 0b10 << 3;
+        public static final byte SHOULD_MERGE_MASK = 0b11 << 3;
+        public static final byte SHOULD_MERGE_CLEAR = 0b1100111;
+    }
+    
+    public static class VertexStateFlag extends FakeFlag {
         public static final byte IS_NON = 0b00 << 5;
         public static final byte IS_RANDOMTAIL = 0b00 << 5;
         public static final byte IS_HEAD = 0b01 << 5;
@@ -23,15 +34,9 @@
         public static final byte VERTEX_CLEAR = (byte) 11001111;
     }
     
-    public static class State extends VertexStateFlag{
-    	public static final byte HEAD_SHOULD_MERGEWITHPREV = 0b101 << 0;
-	    public static final byte HEAD_SHOULD_MERGEWITHNEXT = 0b111 << 0;
-    	    
-        public static final byte NO_MERGE = 0b00 << 3;
-        public static final byte SHOULD_MERGEWITHNEXT = 0b01 << 3;
-        public static final byte SHOULD_MERGEWITHPREV = 0b10 << 3;
-        public static final byte SHOULD_MERGE_MASK = 0b11 << 3;
-        public static final byte SHOULD_MERGE_CLEAR = 0b1100111;
+    public static class FakeFlag{
+        public static final byte IS_NONFAKE = 0 << 0;
+        public static final byte IS_FAKE = 1 << 0;
     }
     
     private PositionListWritable nodeIdList;
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/BasicPathMergeVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/BasicPathMergeVertex.java
index 821117b..3039bc1 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/BasicPathMergeVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/BasicPathMergeVertex.java
@@ -415,8 +415,6 @@
                 sendMsg(incomingMsg.getSourceVertexId(), outgoingMsg); //getPreDestVertexId(getVertexValue())
                 break; 
         }
-//        if(headBecomeOldHead)
-//            getVertexValue().processDelete(neighborToMeDir, incomingMsg.getSourceVertexId());
     }
     
     /**
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/MapReduceVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/MapReduceVertex.java
index 0cc198b..5f70772 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/MapReduceVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/MapReduceVertex.java
@@ -3,12 +3,14 @@
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
+import java.util.Random;
 
 import edu.uci.ics.genomix.pregelix.client.Client;
 import edu.uci.ics.genomix.pregelix.format.GraphCleanInputFormat;
-import edu.uci.ics.genomix.pregelix.format.GraphCleanOutputFormat;
+import edu.uci.ics.genomix.pregelix.format.P2PathMergeOutputFormat;
 import edu.uci.ics.genomix.pregelix.io.MessageWritable;
 import edu.uci.ics.genomix.pregelix.io.VertexValueWritable;
+import edu.uci.ics.genomix.pregelix.io.VertexValueWritable.State;
 import edu.uci.ics.genomix.pregelix.type.MessageFlag;
 import edu.uci.ics.genomix.type.KmerBytesWritable;
 import edu.uci.ics.genomix.type.KmerListWritable;
@@ -19,45 +21,102 @@
 public class MapReduceVertex extends
     BasicPathMergeVertex {
     
-    KmerListWritable kmerList = new KmerListWritable(kmerSize);
-    Map<KmerBytesWritable, KmerListWritable> kmerMapper = new HashMap<KmerBytesWritable, KmerListWritable>();
+    private static boolean fakeVertexExist = false;
+    private static KmerBytesWritable fakeVertex = null;
+    
+    private KmerBytesWritable reverseKmer;
+    private KmerListWritable kmerList = null;
+    private Map<KmerBytesWritable, KmerListWritable> kmerMapper = new HashMap<KmerBytesWritable, KmerListWritable>();
+
+    /**
+     * initiate kmerSize, maxIteration
+     */
+    public void initVertex() {
+        if (kmerSize == -1)
+            kmerSize = getContext().getConfiguration().getInt(KMER_SIZE, 5);
+        if (maxIteration < 0)
+            maxIteration = getContext().getConfiguration().getInt(ITERATIONS, 1000000);
+        if(incomingMsg == null)
+            incomingMsg = new MessageWritable(kmerSize);
+        if(outgoingMsg == null)
+            outgoingMsg = new MessageWritable(kmerSize);
+        else
+            outgoingMsg.reset(kmerSize);
+        if(reverseKmer == null)
+            reverseKmer = new KmerBytesWritable(kmerSize);
+        if(kmerList == null)
+            kmerList = new KmerListWritable(kmerSize);
+        else
+            kmerList.reset(kmerSize);
+        if(fakeVertex == null){
+            fakeVertex = new KmerBytesWritable(kmerSize + 1);
+            String random = generaterRandomString(kmerSize + 1);
+            fakeVertex.setByRead(random.getBytes(), 0); 
+        }
+    }
+    
+    /**
+     * Generate random string from [ACGT]
+     */
+    public String generaterRandomString(int n){
+        char[] chars = "ACGT".toCharArray();
+        StringBuilder sb = new StringBuilder();
+        Random random = new Random();
+        for (int i = 0; i < n; i++) {
+            char c = chars[random.nextInt(chars.length)];
+            sb.append(c);
+        }
+        return sb.toString();
+    }
     
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @Override
     public void compute(Iterator<MessageWritable> msgIterator) {
+        initVertex();
         if(getSuperstep() == 1){
-            //add a fake vertex
-            Vertex vertex = (Vertex) BspUtils.createVertex(getContext().getConfiguration());
-            vertex.getMsgList().clear();
-            vertex.getEdges().clear();
-            KmerBytesWritable vertexId = new KmerBytesWritable();
-            VertexValueWritable vertexValue = new VertexValueWritable();
-            vertexId.setByRead(("XXX").getBytes(), 0);
-            vertexValue.setFakeVertex(true);
-            vertex.setVertexValue(vertexValue);
-            
-            addVertex(vertexId, vertex);
+            if(!fakeVertexExist){
+                //add a fake vertex
+                Vertex vertex = (Vertex) BspUtils.createVertex(getContext().getConfiguration());
+                vertex.getMsgList().clear();
+                vertex.getEdges().clear();
+                VertexValueWritable vertexValue = new VertexValueWritable(kmerSize + 1);
+                vertexValue.setState(State.IS_FAKE);
+                vertexValue.setFakeVertex(true);
+                
+                vertex.setVertexId(fakeVertex);
+                vertex.setVertexValue(vertexValue);
+                
+                addVertex(fakeVertex, vertex);
+                fakeVertexExist = true;
+            }
         }
         else if(getSuperstep() == 2){
             if(!getVertexValue().isFakeVertex()){
-                destVertexId.setByRead(("XXX").getBytes(), 0);
                 outgoingMsg.setSourceVertexId(getVertexId());
                 outgoingMsg.setAcutalKmer(getVertexValue().getKmer());
-                sendMsg(destVertexId, outgoingMsg);
+                sendMsg(fakeVertex, outgoingMsg);
+                voteToHalt();
             }
-            voteToHalt();
         } else if(getSuperstep() == 3){
             kmerMapper.clear();
             /** Mapper **/
             while(msgIterator.hasNext()){
                 incomingMsg = msgIterator.next();
-                tmpKmer.set(incomingMsg.getActualKmer());
+                String kmerString = incomingMsg.getActualKmer().toString();
+                tmpKmer.reset(kmerString.length());
+                reverseKmer.reset(kmerString.length());
+                tmpKmer.setByRead(kmerString.getBytes(), 0);
+                reverseKmer.setByReadReverse(kmerString.getBytes(), 0);
+
+                if(reverseKmer.compareTo(tmpKmer) < 0)
+                    tmpKmer.set(reverseKmer);
                 if(!kmerMapper.containsKey(tmpKmer)){
                     kmerList.reset();
                     kmerList.append(incomingMsg.getSourceVertexId());
                     kmerMapper.put(tmpKmer, kmerList);
                 } else{
                     kmerList.set(kmerMapper.get(tmpKmer));
+                    kmerList.append(incomingMsg.getSourceVertexId());
                     kmerMapper.put(tmpKmer, kmerList);
                 }
             }
@@ -67,9 +126,16 @@
                 for(int i = 1; i < kmerList.getCountOfPosition(); i++){
                     //send kill message
                     outgoingMsg.setFlag(MessageFlag.KILL);
+                    destVertexId.set(kmerList.getPosition(i));
+                    sendMsg(destVertexId, outgoingMsg);
                 }
             }
         } else if(getSuperstep() == 4){
+            /** only for test single MapReduce job**/
+            if(!msgIterator.hasNext() && getVertexValue().getState() == State.IS_FAKE){
+                fakeVertexExist = false;
+                deleteVertex(fakeVertex);
+            }
             while(msgIterator.hasNext()){
                 incomingMsg = msgIterator.next();
                 inFlag = incomingMsg.getFlag();
@@ -89,7 +155,7 @@
          * BinaryInput and BinaryOutput
          */
         job.setVertexInputFormatClass(GraphCleanInputFormat.class);
-        job.setVertexOutputFormatClass(GraphCleanOutputFormat.class);
+        job.setVertexOutputFormatClass(P2PathMergeOutputFormat.class);
         job.setDynamicVertexValueSize(true);
         job.setOutputKeyClass(KmerBytesWritable.class);
         job.setOutputValueClass(VertexValueWritable.class);
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java
index e3af9bf..a14be92 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java
@@ -93,7 +93,6 @@
         inFlag = (byte)0;
         // Node may be marked as head b/c it's a real head or a real tail
         headFlag = (byte) (State.IS_HEAD & getVertexValue().getState());
-        outgoingMsg.reset();
     }
 
     protected boolean isNodeRandomHead(KmerBytesWritable nodeKmer) {
diff --git a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java
index eb17734..6e43552 100644
--- a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java
+++ b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java
@@ -100,7 +100,7 @@
         PregelixJob job = new PregelixJob(jobName);
         job.setVertexClass(MapReduceVertex.class);
         job.setVertexInputFormatClass(GraphCleanInputFormat.class);
-        job.setVertexOutputFormatClass(GraphCleanOutputFormat.class); 
+        job.setVertexOutputFormatClass(P2PathMergeOutputFormat.class); 
         job.setDynamicVertexValueSize(true);
         job.setOutputKeyClass(KmerBytesWritable.class);
         job.setOutputValueClass(VertexValueWritable.class);
@@ -109,7 +109,7 @@
     }
 
     private static void genMapReduceGraph() throws IOException {
-        generateMapReduceGraphJob("LogAlgorithmForMergeGraph", outputBase + "LogAlgorithmForMergeGraph.xml");
+        generateMapReduceGraphJob("MapReduceGraph", outputBase + "MapReduceGraph.xml");
     }
 //    private static void generateTipAddGraphJob(String jobName, String outputPath) throws IOException {
 //        PregelixJob job = new PregelixJob(jobName);
diff --git a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/PathMergeSmallTestSuite.java b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/PathMergeSmallTestSuite.java
index 115f090..8172fb6 100644
--- a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/PathMergeSmallTestSuite.java
+++ b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/PathMergeSmallTestSuite.java
@@ -43,7 +43,7 @@
 public class PathMergeSmallTestSuite extends TestSuite {
     private static final Logger LOGGER = Logger.getLogger(PathMergeSmallTestSuite.class.getName());
 
-    public static final String PreFix = "data/PathMergeTestSet"; //"graphbuildresult";
+    public static final String PreFix = "data/LogAlgorithmForMergeGraph/bin"; //"graphbuildresult";
     public static final String[] TestDir = { PreFix + File.separator
     + "2", PreFix + File.separator
     + "3", PreFix + File.separator
diff --git a/genomix/genomix-pregelix/src/test/resources/only_pathmerge.txt b/genomix/genomix-pregelix/src/test/resources/only_pathmerge.txt
index 5a15ca0..710a096 100644
--- a/genomix/genomix-pregelix/src/test/resources/only_pathmerge.txt
+++ b/genomix/genomix-pregelix/src/test/resources/only_pathmerge.txt
@@ -1 +1 @@
-LogAlgorithmForMergeGraph.xml
+MapReduceGraph.xml