A Re-examination of Query Expansion Using Lexical Resources

Proceedings of ACL-08: HLT, pages 139–147, Columbus, Ohio, USA, June 2008. c⃝2008 Association for Computational Linguistics A Re-examination of Query Expansion Using Lexical Resources Hui Fang Department of Computer Science and Engineering The Ohio State University Columbus, OH, 43210 hfang@cse.ohio-state.edu Abstract Query expansion is an effective technique to improve the performance of information re- trieval systems. Although hand-crafted lexi- cal resources, such as WordNet, could provide more reliable related terms, previous stud- ies showed that query expansion using only WordNet leads to very limited performance improvement. One of the main challenges is how to assign appropriate weights to expanded terms. In this paper, we re-examine this prob- lem using recently proposed axiomatic ap- proaches and find that, with appropriate term weighting strategy, we are able to exploit the information from lexical resources to sig- nificantly improve the retrieval performance. Our empirical results on six TREC collec- tions show that query expansion using only hand-crafted lexical resources leads to signif- icant performance improvement. The perfor- mance can be further improved if the proposed method is combined with query expansion us- ing co-occurrence-based resources. 1 Introduction Most information retrieval models (Salton et al., 1975; Fuhr, 1992; Ponte and Croft, 1998; Fang and Zhai, 2005) compute relevance scores based on matching of terms in queries and documents. Since various terms can be used to describe a same con- cept, it is unlikely for a user to use a query term that is exactly the same term as used in relevant docu- ments. Clearly, such vocabulary gaps make the re- trieval performance non-optimal. Query expansion (Voorhees, 1994; Mandala et al., 1999a; Fang and Zhai, 2006; Qiu and Frei, 1993; Bai et al., 2005; Cao et al., 2005) is a commonly used strategy to bridge the vocabulary gaps by expanding original queries with related terms. Expanded terms are of- ten selected from either co-occurrence-based the- sauri (Qiu and Frei, 1993; Bai et al., 2005; Jing and Croft, 1994; Peat and Willett, 1991; Smeaton and van Rijsbergen, 1983; Fang and Zhai, 2006) or hand- crafted thesauri (Voorhees, 1994; Liu et al., 2004) or both (Cao et al., 2005; Mandala et al., 1999b). Intuitively, compared with co-occurrence-based thesauri, hand-crafted thesauri, such as WordNet, could provide more reliable terms for query ex- pansion. However, previous studies failed to show any significant gain in retrieval performance when queries are expanded with terms selected from WordNet (Voorhees, 1994; Stairmand, 1997). Al- though some researchers have shown that combin- ing terms from both types of resources is effective, the benefit of query expansion using only manually created lexical resources remains unclear. The main challenge is how to assign appropriate weights to the expanded terms. In this paper, we re-examine the problem of query expansion using lexical resources with the recently proposed axiomatic approaches (Fang and Zhai, 2006). The major advantage of axiomatic ap- proaches in query expansion is to provide guidance on how to weight related terms based on a given term similarity function. In our previous study, a co- occurrence-based …

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