AUTOMATIC DERIVATION OF SURFACE TEXT PAT-LOOSE BOUNDS ON THE DIR...

2003. Automatic derivation of surface text pat-loose bounds on the direct use of these resources interns for a maximum entropy based question an-answering TREC questions. We reported the perfor-swering system. HLT-NAACL.mance of these resources on different TREC collec-E.M. Voorhees. 2003. Overview of the trec 2003tions and on different question types. We also quan-question answering track. TREC.tified web retrieval performance, and confirmed thatJ. Xu and W.B. Croft. 1996. Query expansion usingthe web contains a consistently high density of rel-local and global analysis. SIGIR.evant documents containing correct answers evenwhen simple queries are used. The paper alsoJ. Xu, A. Licuanan, and R. Weischedel. 2003. Trecshows that pseudo-relevance feedback alone using2003 qa at bbn: Answering definitional ques-tions. TREC.web documents for query expansions can producea correct answer for fifty percent of the questionsH. Yang, T.S. Chua, S. Wang, and C.K. Koh. 2003.examined.Structured use of external knowledge for event-based open domain question answering. SIGIR.9 AcknowledgementsThis work was supported in part by the AdvancedResearch and Development Activity (ARDA)’sAdvanced Question Answering for Intelligence(AQUAINT) Program.