Update assignment_and_exam.md

assignment_and_exam.md

@@ -361,15 +361,21 @@ Homework
 ![](2015-s-AS2-3-1.png)
 ![](2015-s-AS2-3-2.png)
 2015-EX1-4-EPAL
-
+![](2015-EX1-4.png)
 2015-EX2-5-EPAL
 
+* Explain the notion of policy refinement in Enterprise Privacy Authorization Language (EPAL) and give a scenario in which policy refinement is needed. Describe the main steps of the scope- based policy comparison algorithm for policy refinement.
+
 2014-AS2-3-EPAL
+![](2014-AS2-3.png)
 
 2014-EX1-6-EPAL
 
+![](2014-EX1-6-1.png)
+![](2014-EX1-6-2.png)
 2013-AS2-3-EPAL
 
+![](2013-AS2-3.png)
 2013-EX1-6-EPAL
 
 2012-AS2-3-EPAL