Abstract: Hybrid query expansion methods based on semantic and local analysis can provide time-sensitive extension results with semantic correlation.However,how to effectively combine two different kinds of similarity metrics has not been solved.This paper proposd a hybrid query expansion method based on the Copulas framework to implement the combination of different types of similarity metrics.Based on the query expansion methods of semantic and word co-occurrence analysis,the proposed method respectively calculates the semantical and the statistical similar probabilities between expansion-words and the query words submitted by the user.It then selects high quality extension words to obtain the final extension word set.The experimental results show that the method makes full use of the advantages of the two kinds of query expansion methods to improve the precision ratio factor.The method has better search performance.

Key words: Information retrieval,Query expansion,Semantic analysis,Word co-occurrence analysis,Search performance