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date: 17 December 2017

Abstract and Keywords

A question-answering (QA) system is an application program which takes a user’s natural-language input question and attempts to return a precise answer. This chapter describes the current state of the art of the field of QA. We start with an analysis of the space of questions, and discuss which ones typically are suitable for automatic processing by current systems, how they are studied, and the types of QA system that process them. We look at the composition of a typical QA system, some of the recurring linguistic and semantic problems that QA systems must overcome, and a variety of specific approaches that have been developed to address them. We also describe the typical evaluation metrics used to measure the performance of QA systems. An overview of one specific system, IBM’s Watson, is provided at the end.

Keywords: question-answering, open-domain, closed-domain, definition questions, list questions, answer extraction, answer merging, answer type, answer verification, semantic search

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