1. Department of Mathematics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522; and Center for Advanced Intelligence Project, RIKEN ; and Department of Mathematics , Chuo University , 1-13-27, Kasuga , Bunkyo-ku , Tokyo 112-8551 , Japan
2. Center for Advanced Intelligence Project , RIKEN , Nihonbashi 1-chome Mitsui Building, 15th floor, 1-4-1 Nihonbashi, Chuo-ku Tokyo 103-0027; and Department of Mathematics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 , Japan
3. Center for Advanced Intelligence Project, RIKEN, Tokyo ; and Center for Data Science , Ehime University , 3 Bunkyo-cho, Matsuyama , Ehime 790-8577 , Japan