document: Topic-oriented query expansion for web search The contribution of this paper includes three folders : ( 1 ) To introduce a topic-oriented query expansion model based on the Information Bottleneck theory that classify terms into distinct topical clusters in order to find out candidate terms for the query expansion . ( 2 ) To define a term-term similarity matrix that is available to improve the term ambiguous problem . ( 3 ) To propose two measures , intracluster and intercluster similarities , that are based on proximity between the topics represented by two clusters in order to evaluate the retrieval effectiveness . Results of several evaluation experiments in Web search exhibit the average intracluster similarity was improved for the gain of 79.1 % while the average intercluster similarity was decreased for the loss of 36.0 % .
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