Japanese Q/A System Using A* Search and Its Improvement - Yokohama National University at QAC2

In NTCIR3 QAC1, we proposed a method to introduce an A search control into sentential matching mechanism for Japanese question answering systems, in order to reduce the turn-around time while keeping the accuracy of the answers. Using the method, we do not have to any preprocessing on a document database, and we may use any IR systems with writing a simple wrapper program. There however is a problem that the accuracy was not so high and MRR was about 0.3. In order to improve the accuracy, we therefore propose several measures of degree of sentence matching and a variant of voting method. Both of them can be integrated with our scheme of controlled search. By using those techniques, the system achieves a higher MRR, 0.489, in NTCIR4 QAC2.