1. Department of Computer Science and Technology, State Key Laboratory of Intelligent Technology and Systems, Beijing National Research Center for Information Science and Technology, Institute for Artificial Intelligence, Tsinghua University, Beijing, China
2. Institute of Computing Technology, Chinese Academy of Sciences, Beijing, China
3. School of Engineering and Technology, China University of Geosciences (Beijing), Beijing, China
4. Maersk Mc-Kinney Moller Institute, University of Southern Denmark, Odense, Denmark