Combination strategies for semantic role labeling

  • Authors:
  • Mihai Surdeanu;Lluís Màrquez;Xavier Carreras;Pere R. Comas

  • Affiliations:
  • Technical University of Catalonia, Barcelona, Spain;Technical University of Catalonia, Barcelona, Spain;Technical University of Catalonia, Barcelona, Spain;Technical University of Catalonia, Barcelona, Spain

  • Venue:
  • Journal of Artificial Intelligence Research
  • Year:
  • 2007

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Abstract

This paper introduces and analyzes a battery of inference models for the problem of semantic role labeling: one based on constraint satisfaction, and several strategies that model the inference as a meta-learning problem using discriminative classifiers. These classifiers are developed with a rich set of novel features that encode proposition and sentence-level information. To our knowledge, this is the first work that: (a) performs a thorough analysis of learning-based inference models for semantic role labeling, and (b) compares several inference strategies in this context. We evaluate the proposed inference strategies in the framework of the CoNLL-2005 shared task using only automatically-generated syntactic information. The extensive experimental evaluation and analysis indicates that all the proposed inference strategies are successful - they all outperform the current best results reported in the CoNLL-2005 evaluation exercise - but each of the proposed approaches has its advantages and disadvantages. Several important traits of a state-of-the-art SRL combination strategy emerge from this analysis: (i) individual models should be combined at the granularity of candidate arguments rather than at the granularity of complete solutions; (ii) the best combination strategy uses an inference model based in learning; and (iii) the learning-based inference benefits from max-margin classifiers and global feedback.