1. Keio Institute of Pure and Applied Sciences (KiPAS) and Department of Mathematics, Keio University, Yokohama, Japan; and Mathematical Science Team, RIKEN Center for Advanced Intelligence Project, Chuo-ku, Tokyo, Japan
2. Department of Mathematics, Keio University, Yokohama, Japan; and Mathematical Science Team, RIKEN Center for Advanced Intelligence Project, Chuo-ku, Tokyo, Japan
3. Faculty of Mathematics, Kyushu University, Fukuoka, Japan
4. Department of Mathematics, Keio University, Yokohama, Japan
5. Keio Institute of Pure and Applied Sciences (KiPAS) and Department of Mathematics,, Keio University, Yokohama, Japan; and Mathematical Science Team, RIKEN Center for Advanced Intelligence Project, Chuo-ku, Tokyo, Japan
6. Department of Mathematics, Osaka University, Osaka, Japan; and Mathematical Science Team, RIKEN Center for Advanced Intelligence Project, Chuo-ku, Tokyo, Japan