1. Department of Computer Science and Engineering, University of California
at San Diego, La Jolla, California, U.S.A.
2. School of Computing, Soongsil University, Seoul, Korea
3. Department of Computer Science, University of Tennessee, Knoxville,
Tennessee, U.S.A.
4. Department of Computer Science, University of Tennessee, Knoxville, and
Mathematical Science Section, Oak Ridge National Laboratory, Tennessee, U.S.A.