Affiliation: | (1) Department of Informatics and Mathematical Science, Institute of Technology and Science, The University of Tokushima, Tokushima 770-8506, Japan;(2) Department of Mathematics, Graduate School of Economics, Hitotsubashi University, Kunitachi, Tokyo 186-8601, Japan;(3) Graduate School of Commerce and Management, Hitotsubashi University, Kunitachi, Tokyo 186-8601, Japan;(4) Present address: The Japan Research Institute, Tokyo 102-0082, Japan;(5) Present address: College of Science and Technology, Nihon University, Kanda-Surugadai, Tokyo 101-8308, Japan |