Extracting Answer in QA System: Learning Based

Converting questions to effective queries is crucial to open-domain question answering systems. In this paper, we present a web-based unsupervised learning approach for transforming a given natural-language question to an effective query. The method involves querying a search engine for web passages that contain the answer to the question, extracting patterns that characterize fine-grained classification for answers. Independent evaluation on a set of questions shows that the proposed approach outperforms a naive keyword based approach.