[1] Kyoto Univ, Grad Sch Informat, Dept Syst Sci, Kyoto 6068501, Japan
[2] Univ Tokyo, Inst Adv Study, Int Res Ctr Neurointelligence WPI IRCN, Tokyo 1130033, Japan
[3] Adv Telecommun Res Inst Int ATR, Seika 6190288, Japan
[4] Hanyang Univ, Dept Comp Software, Seoul 04763, South Korea