Exploiting CCG structures with tree kernels for speculation detection

  • Authors:
  • Liliana Mamani Sánchez;Baoli Li;Carl Vogel

  • Affiliations:
  • Trinity College Dublin, Dublin, Ireland;Trinity College Dublin, Dublin, Ireland;Trinity College Dublin, Dublin, Ireland

  • Venue:
  • CoNLL '10: Shared Task Proceedings of the Fourteenth Conference on Computational Natural Language Learning --- Shared Task
  • Year:
  • 2010

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Abstract

Our CoNLL-2010 speculative sentence detector disambiguates putative keywords based on the following considerations: a speculative keyword may be composed of one or more word tokens; a speculative sentence may have one or more speculative keywords; and if a sentence contains at least one real speculative keyword, it is deemed speculative. A tree kernel classifier is used to assess whether a potential speculative keyword conveys speculation. We exploit information implicit in tree structures. For prediction efficiency, only a segment of the whole tree around a speculation keyword is considered, along with morphological features inside the segment and information about the containing document. A maximum entropy classifier is used for sentences not covered by the tree kernel classifier. Experiments on the Wikipedia data set show that our system achieves 0.55 F-measure (in-domain).