Affiliation: | a Department of Applied Mathematics and Physics, Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan b Department of Computer Science and Mathematical Informatics, Graduate School of Information Science, Nagoya University, Furocho, Chikusaku, Nagoya 464-8603, Japan c Department of Informatics, School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan |