Extracting opinion expressions and their polarities: exploration of pipelines and joint models

  • Authors:
  • Richard Johansson;Alessandro Moschitti

  • Affiliations:
  • DISI, University of Trento, Via Sommarive, Trento (TN), Italy;DISI, University of Trento, Via Sommarive, Trento (TN), Italy

  • Venue:
  • HLT '11 Proceedings of the 49th Annual Meeting of the Association for Computational Linguistics: Human Language Technologies: short papers - Volume 2
  • Year:
  • 2011

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Abstract

We investigate systems that identify opinion expressions and assigns polarities to the extracted expressions. In particular, we demonstrate the benefit of integrating opinion extraction and polarity classification into a joint model using features reflecting the global polarity structure. The model is trained using large-margin structured prediction methods. The system is evaluated on the MPQA opinion corpus, where we compare it to the only previously published end-to-end system for opinion expression extraction and polarity classification. The results show an improvement of between 10 and 15 absolute points in F-measure.