1. University of Illinois Urbana-Champaign, Champaign, IL, USA
2. University of Michigan, Ann Arbor, Ann Arbor, MI, USA
3. Tsinghua University, Beijing, China
4. Amazon & University of Michigan, Ann Arbor, Ann Arbor, MI, USA
5. Google Research, New York, NY, USA
6. Harvard University, Boston, MA, USA