SPIDER Retrieval System at TREC-5

The ETH group participated in this year's TREC in the following tracks: automatic adhoc (long and short), the manual adhoc, routing and confusion. We also did some experiments on the Chinese data which were not submitted. While for adhoc we relied mainly on methods which were well evaluated in previous TRECs, we successfully tried completely new techniques for the routing task and the confusion task: for routing we found an optimal feature selection method and included co-occurrence data into the retrieval function; for confusion we applied a robust probabilistic technique for estimating feature frequencies