TREC-4 Ad-Hoc, routing retrieval and filtering experiments using PIRCS
Kui Lam Kwok, Laszlo Grunfeld · 1995
Our ad-hoc submissions are pircs1 which is fully automatic, and pircs2 which involves manually weighting some terms and adding some new words to the original topic descriptions. The number of words added are minimal. Both methods involve training and query expansion using the best-ranked subdocuments from an initial retrieval as feedback. For our routing experiments we make use of massive query expansion of 350 terms in pircsL, with emphasis on expansion with low frequency terms. Training is done using short and top-ranked known relevant subdocuments. In pircsC, we define four different 'expert' queries (pircsL being one of them) for each topic by using different subsets of training document, and later combine their retrieval results into one. Filtering experiment is done with the retrieval lists of pircsL. For each query, we use the training collections to define retrieval status values (RSVs) where the utilities are maximum for the three precision types. These RSVs are then used as t...