1. Department of Complexity Science and Engineering, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
2. Artificial Intelligence Research Center, AIST, Koto, Tokyo 135-0064, Japan
3. PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
4. RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
5. Center for Materials Research by Information Integration, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan