A comparative study of word co-occurrence for term clustering in language model-based sentence retrieval

  • Authors:
  • Saeedeh Momtazi;Sanjeev Khudanpur;Dietrich Klakow

  • Affiliations:
  • Saarland University;Johns Hopkins University;Saarland University

  • Venue:
  • HLT '10 Human Language Technologies: The 2010 Annual Conference of the North American Chapter of the Association for Computational Linguistics
  • Year:
  • 2010

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Abstract

Sentence retrieval is a very important part of question answering systems. Term clustering, in turn, is an effective approach for improving sentence retrieval performance: the more similar the terms in each cluster, the better the performance of the retrieval system. A key step in obtaining appropriate word clusters is accurate estimation of pairwise word similarities, based on their tendency to co-occur in similar contexts. In this paper, we compare four different methods for estimating word co-occurrence frequencies from two different corpora. The results show that different, commonly-used contexts for defining word co-occurrence differ significantly in retrieval performance. Using an appropriate co-occurrence criterion and corpus is shown to improve the mean average precision of sentence retrieval form 36.8% to 42.1%.