Answer Validation based on Association of Keywords in a Question Sentence and Answer Candidates

Answer validation is a component of question answering system, which selects the most reliable answer from the answer candidates that are extracted by certain meth-ods. In this paper, we propose a new approach of answer validation based on the strength of lexical association between keywords in a question sentence and each of the answer candidates, and examines the effectiveness of the approach; we use search engine hits to calculate the association score. We propose two types of answer se-lection methods based on the association score. The first method first extracts the appropriate keywords from a given question sentence using word weights and then selects the final answer by using the association score. The second method selects appropriate keywords and answer candidate simultaneously using the association score.The result of experimental evaluation shows that a good proportion (79%) of a multiple-choice quiz “Who wants to be a millionaire” can be solved by combin-ing these two methods. The proposed method significantly outperforms a previous method for answer selection based on search engine hits.