Web文書を対象とした質問の型に依らない質問応答手法

概要

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In this paper, we propose a method of non-factoid Web question-answering that can uniformly deal with any class of Japanese non-factoid question by using a large number of example Q&A pairs. Instead of preparing classes of questions beforehand, the method retrieves already asked question examples similar to a submitted question from a set of Q&A pairs. Then, instead of preparing clue expressions for the writing style of answers according to each question class beforehand, it dynamically extracts clue expressions from the answer examples corresponding to the retrieved question examples. This clue expression information is combined with topical content information from the question to extract appropriate answer candidates. The score of an answer candidate is measured by the density of submitted questions keywords, words associated with the question and the clue expressions. Note that we utilize the set of Q&A pairs, not to find answers from them, but to obtain clue expressions about the writing style of their answers. The information source for question answering is the Web documents retrieved by using an API of a Web search engine. Experimental results showed that the clue expressions obtained from the set of examples improved the accuracy of answer candidate extraction.