Analyzing Explicitly-Structured Discourse in a Limited Domain: Trouble and Failure Reports

ANALYZING EXPLICITLY-STRUCTURED DISCOURSE IN A LIMITED DOMAIN: TROUBLE AND FAILURE REPORTS* Catherine N. Ball Unisys Corporation Paoli Research Center P.O. Box 517, Paoli PA 19301 ABSTRACT Recent theories of focusing and reference rely crucially on discourse structure to constrain the availability of discourse entities for reference, but deriving the structure of an arbitrary discourse has proved to be a significant problem. A useful level of problem reduction may be achieved by analyzing discourse in which the structure is explicit, rather than implicit. In this paper we consider a genre of explicitly-structured discourse: the Trouble and Failure Report (TFR), whose structure is both explicit and constant across discourses. We present the results of an analysis of a corpus of 331 TFRs, with particular attention to discourse segmentation and focusing. We then describe how the Trouble and Failure Report was automated in a prototype data collection and information retrieval application, using the PUNDIT natural-language processing system. INTRODUCTION Recent theories of focusing and reference rely crucially on discourse structure to constrain the availability of discourse entities for reference, but deriving the structure of an arbitrary discourse has proved to be a significant problem ([Webber 881). While progress has been made in identifying the means by which speakers and writers mark structure ([Grosz 86], [Hirschberg 87], [Schiffrin 87], [Webber 88]), much work remains to be done in this area. As is well known, initial progress in computational approaches to syntax and semantics was facilitated by reducing the problem space to discourses in technical sublanguages, in simplified registers, in restricted domains 1. For Computational Pragmatics, the analysis of explicitly-structured discourse can provide a • similar level of problem reduction. By removing the theoretical obstacle of deriving discourse structure, we can more readily evaluate the effect of this structure on focusing and reference. In this paper we consider a genre of explicitly-structured discourse, namely the 'form', in which each labelled box and the response within it constitute a discourse segment. From the perspective of discourse understanding, the study of forms-discourse offers considerable advantages: the structure of the form is pre-defined and constant across discourses, and it is possible to study patterns of reference in narrative responses without excessive reliance on intuition. The particular form which we consider here is the Trouble and Failure Report (TFR). We first discuss the results of an analysis of 331 TFRs, and then describe the implementation of a TFR analysis module using the PUNDIT natural-language processing system. THE TROUBLE AND FAILURE REPORT TFRs are used to report problems with hardware, software, or documentation on equipment on board Trident and Poseidon submarines. These reports originate on board the submarine, and those concerning the Navigational Subsystem (which is managed by the Unisys Logistics Group) are routed to Unisys for analysis and response. *This work has been supported by DARPA contract N00014-85-C-0012, administered by the Office of Naval Research. 1See for example the papers in [Grishman 86b]. 266 The TFR contains a formatted section and up to 99 lines of free text. The formatted …

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