This paper proposes a method to overcome the drawbacks of WordNet when applied to information retrieval by complementing it with Roget's thesaurus and corpus-derived thesauri. Words and relations which are not included in WordNet can be found in the corpus-derived thesauri. Effects of polysemy can be minimized with weighting m e t h o d considering all query terms and all of the thesauri. Experimental results show that our method enhances information retrieval performance significantly. expansion (Voorhees, 1994; Smeaton and Berrut, 1995), computing lexical cohesion (Stairmand, 1997), word sense disambiguation (Voorhees, 1993), and so on, but the results have.
