Index Pruning and Result Reranking: Effects on Ad-Hoc Retrieval and Named Page Finding.
Stefan Büttcher, Charles L. A. Clarke, Peter C. K. Yeung · Text REtrieval Conference · 2006
We describe experiments conducted for the TREC 2006 Terabyte track. Our experiments are centered around two concepts: Static index pruning (for increased retrieval eciency) and result reranking (for improved precision). We investigate their eect on retrieval eciency and eectiveness, paying special attention to the dierence between ad-hoc retrieval and named page nding. We show that index pruning and reranking based on relevance models can be benecial in an ad-hoc retrieval setting, but have a disastrous repercussion on the eectiv eness of named page nding. Result reranking based on anchor text, on the other hand, is very useful for named page nding, but should not be used for ad-hoc retrieval. This dichotomy poses a problem for search engines, as there is no easy way for a search engine to decide whether a given query represents an ad-hoc retrieval task, with the purpose to satisfy an abstract information need, or a named page nding task, targeting a specic document.