[1] Univ Minnesota, Dept Comp Sci & Engn, Minneapolis, MN 55455 USA
[2] Univ Florida, Comp & Informat Sci & Engn Dept, Gainesville, FL 32611 USA
[3] Univ Calif Irvine, Dept Comp Sci, Irvine, CA 92697 USA
[4] Univ Tokyo, Dept Mechanoinformat, Grad Sch Informat Sci & Technol, Tokyo 1138654, Japan