diff --git a/genomix/genomix-hadoop/pom.xml b/genomix/genomix-hadoop/pom.xml
index 610092a..8ca2fa3 100755
--- a/genomix/genomix-hadoop/pom.xml
+++ b/genomix/genomix-hadoop/pom.xml
@@ -174,5 +174,11 @@
 			<type>test-jar</type>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.mrunit</groupId>
+			<artifactId>mrunit</artifactId>
+			<version>1.0.0</version>
+			<classifier>hadoop1</classifier>
+		</dependency>
 	</dependencies>
 </project>
diff --git a/genomix/genomix-hadoop/src/main/java/edu/uci/ics/genomix/hadoop/velvetgraphbuilding/GraphBuildingDriver.java b/genomix/genomix-hadoop/src/main/java/edu/uci/ics/genomix/hadoop/velvetgraphbuilding/GraphBuildingDriver.java
index eaf2a6f..c735a0d 100644
--- a/genomix/genomix-hadoop/src/main/java/edu/uci/ics/genomix/hadoop/velvetgraphbuilding/GraphBuildingDriver.java
+++ b/genomix/genomix-hadoop/src/main/java/edu/uci/ics/genomix/hadoop/velvetgraphbuilding/GraphBuildingDriver.java
@@ -52,6 +52,7 @@
     public void run(String inputPath, String outputPath, int numReducers, int sizeKmer, int readLength,
             boolean onlyTest1stJob, boolean seqOutput, String defaultConfPath) throws IOException {
         if (onlyTest1stJob == true) {
+            
             runfirstjob(inputPath, numReducers, sizeKmer, readLength, seqOutput, defaultConfPath);
         } else {
             runfirstjob(inputPath, numReducers, sizeKmer, readLength, true, defaultConfPath);
@@ -113,6 +114,7 @@
 
         conf.setPartitionerClass(ReadIDPartitioner.class);
 
+        // grouping is done on the readID only; sorting is based on the (readID, abs(posn)) 
         conf.setOutputKeyComparatorClass(PositionWritable.Comparator.class);
         conf.setOutputValueGroupingComparator(PositionWritable.FirstComparator.class);