Affiliation: | a Graduate School of Informatics, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan b Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan c ERATO Aihara Complexity Modelling Project, JST, 3-23-5 Uehara, Shibuya-ku, Tokyo 151-0064, Japan |