Japanese Question-Answering System Using A~* Search and Its Improvement

摘要

We have proposed a method to introduce A~* search control in a sentential matching mechanism for Japanese question-answering systems in order to reduce the turnaround time while maintaining the accuracy of the answers. Using this method, preprocessing need not be performed on a document database and we may use any information retrieval systems by writing a simple wrapper program. However, the disadvantage is that the accuracy is not sufficiently high and the mean reciprocal rank (MRR) is approximately 0.3 in NTCIR3 QAC1, an evaluation workshop for question-answering systems. In order to improve the accuracy, we propose several measures of the degree of sentence matching and a variant of a voting method. Both of them can be integrated with our system of controlled search. Using these techniques, the system achieves a higher MRR of 0.5 in the evaluation workshop NTCIR4 QAC2.