Department of Computer Science, University of California, Santa Barbara, CA 93106, USA. bruttenberg@cra.com|Department of Computer Science, University of California, Santa Barbara, CA 93106, USA. bruttenberg@cra.com|Department of Computer Science, University of California, Santa Barbara, CA 93106, USA. bruttenberg@cra.com|Department of Computer Science, University of California, Santa Barbara, CA 93106, USA. bruttenberg@cra.com|Department of Computer Science, University of California, Santa Barbara, CA 93106, USA. bruttenberg@cra.com