The linked dependence assumption, a widely used simplification in probabilistic retrieval, is briey reviewed and its validity is investigated. We show that the linked dependence assumption is violated particularly if the query features are good discriminators between relevant and non-relevant documents. We then propose the manual concept generation method, which takes into account the dependence between different query concepts. For a limited set of routing queries, experiments show a significant improvement when compared with retrieval methods which do not take into account feature dependencies. We consider this method to be the first successful step which progresses beyond the linked dependence assumption.
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Institute for Operations Research