Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.MIT Institute Archives copy: p. 29-56 bound in reverse order.Includes bibliographical references (p. 54-56).Prism is an answer projection system that combines the best attributes of traditional and Web-based question answering systems. Traditional question answering systems retrieve answers with pinpoint accuracy but limited coverage, using a small and reliable data source, while Web-based systems retrieve answers with broad coverage but limited accuracy, using a large but noisy data source. By taking advantage of the strengths of each system, an answer projection system can answer as many questions as a Web-based system while still being as accurate as a traditional system. In fact, Prism improves the performance of a traditional question answering system by 25%. It improves the accuracy of answers retrieved from the World Wide Web by 10%, and more importantly, it verifies answers retrieved from the Web by providing reliable supporting documents. By combining Prism with traditional and Web-based systems, we obtain a question answering system with high accuracy and broad coverage.by Lynn Wu.M.Eng
