Robust parsing for spoken language systems

  • Authors:
  • Stephanie Seneff

  • Affiliations:
  • Laboratory for Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts

  • Venue:
  • ICASSP'92 Proceedings of the 1992 IEEE international conference on Acoustics, speech and signal processing - Volume 1
  • Year:
  • 1992

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Abstract

This paper describes a recent extension to the MIT ATIS (Air Travel Information Service) system, which allows it to answer a question when a full linguistic analysis fails. This "robust" parsing capability was achieved through minor extensions of pre-existing components already in place for the full linguistic analysis component. Robust parsing is applied only after a full analysis has failed, and it involves the two stages of 1) parsing a set of phrases and clauses, and 2) gluing them together to obtain a single semantic frame encoding the full meaning of the sentence. In a recent evaluation on text input collected at multiple sites within the DARPA community, less than two thirds of the sentences yielded a full parse, but the overwhelming majority of the remaining sentences were analyzed correctly by the robust parsing scheme. We also analyzed the results when text input was replaced by recognizer outputs [3]. Even though the recognizer produced greater than 50% sentence error rate, the drop in score (%correct - %incorrect) was only 10 percentage points. This result leads to the conclusion that most of the recognizer errors are harmless in terms of meaning analysis, as long as a robust mechanism for accounting for the parsable phrases is in place.