Query expansion is the process of adding additional relevant terms to the original queries to improve the performance of information retrieval systems. However, previous studies showed that automatic query expansion using WordNet do not lead to an improvement in the performance. One of the main challenges of query expansion is the selection of appropriate terms. In this paper, the authors revie...

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Query expansion is an effective technique in improving the retrieval performance for ad-hoc retrieval. However, query expansion can also fail, leading to a degradation of the retrieval performance. In this paper, we aim to provide a better understanding of query expansion by an empirical study on what factors can affect query expansion, and how these factors affect query expansion. We examine h...

In this paper we present a method for answering relationship questions, as posed for example in the spring of 2003 evaluation exercise of the AQUAINT program, which has funded this research. The goal of the exercise was to provide answers to questions requesting an account of the relationship between two or more entities. No restriction on the format of the answer was imposed, except that it sh...

Based on a relatively large subset representing one third of the MEDLINE collection, this paper evaluates ten different IR models (probabilistic, language model and vector-space approaches) using three different stemmers. The impact that manually assigned descriptors (MeSH headings) have on retrieval effectiveness is also evaluated. Finally, we propose both a new general blind-query expansion a...

In 1987 Kalkbrenner and Stifter tested Collins' QE algorithm on various collision problems. In this paper we report the test results of applying Hong's improved QE algorithm on the same set of problems. The tests show that the improved QE algorithm gives signiicant speedups, ranging from 30 times to at least 7000 times.

This paper describes how we managed to use the WordNet ontology for the GeoCLEF 2005 English monolingual task. Both a query expansion method, based on the expansion of geographical terms by means of WordNet synonyms and meronyms, and a method based on the expansion of