1. Microsoft Research, Redmond, United States. bapeng@microsoft.com
2. Microsoft Research, Redmond, United States. chunyl@microsoft.com
3. Microsoft Research, Redmond, United States. jincli@microsoft.com
4. Microsoft Research, Redmond, United States. shahins@microsoft.com
5. Microsoft Research, Redmond, United States. lars.liden@microsoft.com
6. Microsoft Research, Redmond, United States. jfgao@microsoft.com