1. Nagoya University, Japan. E-mail: matuzaki@nuee.nagoya-u.ac.jp
2. Fujitsu Laboratories, Ltd., Japan. E-mails: iwane@jp.fujitsu.com, anai@jp.fujitsu.com
3. University of Tsukuba, Japan. E-mail: munehiro-k@math.tsukuba.ac.jp
4. Université Paris Diderot, France. E-mail: pon.zhan@gmail.com
5. Tokyo University of Science, Japan. E-mails: ryoya.0323@gmail.com, 1414606@alumni.tus.ac.jp
6. National Institute of Informatics, Japan. E-mail: arai@nii.ac.jp