The University of Amsterdam at the TREC 2007 Enterprise Track

We describe our participation in the TREC 2007 Enterprise track and detail our lan- guage modeling-based approaches. For document search, our focus was on estimating a mixture model using a standard web collection, and on constructing query models by employing blind relevance feedback and using the example docu- ments provided with the topics. We found that settings performing well on a web collection do not carry over to the CSIRO collection, but the use of advanced query models resulted in significant improvements. In expert search, our experiments concerned document representation, identification of candidate experts, and combinations of expert search strategies. We find no significant differ- ence in average precision but observe small overall positive effects of the advanced models, with large differences between individual topics.