Department of Computer Science, University of California, Santa Barbara, Santa Barbara, CA 93106-5110, USA. tamer@cs.ucsb.edu|Department of Computer Science, University of California, Santa Barbara, Santa Barbara, CA 93106-5110, USA. tamer@cs.ucsb.edu|Department of Computer Science, University of California, Santa Barbara, Santa Barbara, CA 93106-5110, USA. tamer@cs.ucsb.edu