Affiliation: | (1) Department of Mathematics and Information Sciences, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397, Japan;(2) Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan;(3) Department of Mathematics, Graduate School of Engineering, Gunma University, Kiryu 376-8515, Japan |