Searching Questions by Identifying Question Topic and Question Focus Huizhong Duan author Yunbo Cao author Chin-Yew Lin author Yong Yu author 2008-06 text Proceedings of ACL-08: HLT Johanna D Moore editor Simone Teufel editor James Allan editor Sadaoki Furui editor Association for Computational Linguistics Columbus, Ohio conference publication duan-etal-2008-searching https://aclanthology.org/P08-1019/ 2008-06 156 164