CLIPS at TREC 11: Experiments in Filtering

At the TREC9 conference, we presented a new adaptive filtering system called RELIEFS. This system which is based on the idea of resonance, combines for each term t, the relative frequency of relevance knowing t and the relative frequency of t kwowing relevance. On the basis of other experiments, several changes have been made. We improved our threshold adaption, we slightly changed our relevance evaluation function and we gave up the use of conjunctions and thesaurus. The system is now focusing more exclusively on the combination of both reverse frequencies that we believe to represent the fundamental aspects of relevance estimation. This year we used the system in its new version and we tested it on the Reuters corpus. Focusing on the combination of the two frequencies, we varied their relative importance. The results show globally a good effectiveness especially when both frequencies are balanced.