Details of Research Outputs

A meta-search engine propagates user queries to its participant search engines following a server selection strategy. To facilitate server selection, the meta-search engine must keep concise descriptors about the document collections indexed by the participant search engines. Most existing approaches record in the descriptors information about what terms appear in a document collection, but they skip information about which documents a keyword appears in. This results in ineffective server ranking for multi-term queries, because a document collection may contain all of the query terms but not all of the terms appear in the same document. In this paper, we propose a server ranking approach in which each search engine's document collection is divided into clusters by indexed terms. Furthermore, we keep the term correlation information in a cluster descriptor as a concise method to estimate the degree of term co-occurrence in a document set. We empirically show that combining clustering and term correlation analysis significantly improves search precision and that our approach effectively identifies the most relevant servers even with a naïve clustering method and a small number of clusters. © Springer-Verlag 2004.