file - ChaSen - 奈良先端科学技術大学院大学

Chapter 1Introduction1.1 MotivationQuestion-answering(QA) is the most natural way of exchanging information inhuman interaction. It is an ideal form in studies of question-answering in humancomputerinteraction, much of the studies have been gradually conducted to thisgoal. In a recent decade, the studies of new information accessibility to hugeamount of documents have been made by TREC (Text Retrieval Conference)[82, 155] and NTCIR (NII Test Collection for IR Systems). Their studies comprisemany advanced information access methodologies, such as speech interfaceframework, web information retrieval, information navigation, intelligent informationaccess, and cross-language retrieval.Current advanced question-answering can also be positioned in this stream ofresearch, QA-Track in TREC [154] started in 1999 and NTCIR QAC(Questionand Answering Challenge) [68] has been held annually since 2001. Questionansweringwork as a useful interface of an information retrieval engine that isable to accept sentence queries. Question-answering provides the answer to theuser question by extracting the exact answer in retrieved articles from a largeamount of source documents, databases or Web pages. Because this kind ofquestion-answering addresses queries in unrestricted domains, it is called opendomain question-answering. It mainly accepts only single sentence queries. Forinstance, questions in TREC take the form What is the capital of Uruguay? How did Socrates die? Where is the Taj Mahal? When did the Jurassic1