Institution: | 1. Department of Mathematical and Natural Sciences, The University of Tokushima, Tokushima 770-8502, Japan;2. Department of Information and Management Science, Otaru University of Commerce, Otaru 047-8501, Japan;3. Department of Economic Engineering, Kyushu University, Fukuoka 812-8581, Japan;4. Department of Mathematics and Information Sciences, Graduate School of Science, Osaka Prefecture University, Sakai 599-8531, Japan |