Affiliation: | 1. Department of Computer Science and System Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan;2. Department of Mathematics, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan;3. Department of Computer Science and Communication Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0935, Japan |