1. Department of Computer Science, Northwestern University, Evanston, IL, USA
2. Department of Computer Science, Dartmouth College, Hanover, NH, USA
3. DIMES, University of Calabria, Arcavacata, Italy
4. Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
5. Centre for Artificial Intelligence and Robotics and Hong Kong Institute of Science and Innovation, Chinese Academy of Science, Hong Kong, Hong Kong