UWashington: negation resolution using machine learning methods

  • Authors:
  • James Paul White

  • Affiliations:
  • University of Washington, Box Seattle, WA

  • Venue:
  • SemEval '12 Proceedings of the First Joint Conference on Lexical and Computational Semantics - Volume 1: Proceedings of the main conference and the shared task, and Volume 2: Proceedings of the Sixth International Workshop on Semantic Evaluation
  • Year:
  • 2012

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Abstract

This paper reports on a simple system for resolving the scope of negation in the closed track of the *SEM 2012 Shared Task. Cue detection is performed using regular expression rules extracted from the training data. Both scope tokens and negated event tokens are resolved using a Conditional Random Field (CRF) sequence tagger -- namely the SimpleTagger library in the MALLET machine learning toolkit. The full negation F1 score obtained for the task evaluation is 48.09% (P=74.02%, R=35.61%) which ranks this system fourth among the six submitted for the closed track.