Computer Science Department, Technion, Haifa, Israel. eraneden@cs.technion.ac.il|Computer Science Department, Technion, Haifa, Israel. eraneden@cs.technion.ac.il|Computer Science Department, Technion, Haifa, Israel. eraneden@cs.technion.ac.il|Computer Science Department, Technion, Haifa, Israel. eraneden@cs.technion.ac.il