| Summary: | 碩士 === 國立中央大學 === 資訊管理研究所 === 99 === In information retrieval systems, the system performance can be improved by the application of relevance feedback and query expansion. In fact, the contents of the relevant documents do not always match the information needs of the users. There are still several non-relevant and meaningless noise blocks in the documents and those noises will affect the performance of document retrieval. In this research, it attempts to eliminate the effect of the noises from relevance feedback by using passages information, and also discuss this impact of different passages combination on the performance of second document retrieval. In the experiments, our system first splits the contents of the documents into passages, and then selects passages according to the selection method to use in query expansion. Finally, we use the precision of second document retrieval to discuss the influence of different passage selection methods.
According to the results of experiments, the system performance can be improved by using passages information. The precision of second document retrieval which using passages information is better than the performance which using full-text information. This study has proved that the passages information is very useful on query expansion.
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