Experiments on the determination of the relationships between terms

The retrieval effectiveness of an automatic method that uses relevance judgments for the determination of positive as well as negative relationships between terms is evaluated. The term relationships are incorporated into the retrieval process by using a generalized similarity function that has a term match component, a positive term relationship component, and a negative term relationship component. Two strategies, query partitioning and query clustering, for the evaluation of the effectiveness of the term relationships are investigated. The latter appears to be more attractive from linguistic as well as economic points of view. The positive and the negative relationships are verified to be effective both when used individually, and in combination. The importance attached to the term relationship components relative to that of term match component is found to have a substantial effect on the retrieval performance. The usefulness of discriminant analysis as a technique for determining the relative importance of these components is investigated.