1. Information and Physical Sciences, Graduate School of Information Science and Technology, Osaka University, Yamadaoka 1-5, Suita, Osaka, 565-0871, Japan ().
2. Department of Mathematics, Hokkaido University, Sapporo 060-0810, Japan ().
3. Department of Applied Mathematics and Informatics, Ryukoku University, Seta Otsu 520-2194, Japan ().