Semantic Acquisition In TELI: A Transportable, User-Customized Natural Language Processor

Semantic Acquisition In TELI: A Transportable, User-Customized Natural Language Processor Bruce W. Ballard Douglas E. Stumberger AT&T Bell Laboratories 600 Mountain Avenue Murray Hill, NJ 07974 Abstract We discuss ways of allowing the users of a natural language processor to define, examine, and modify the definitions of any domain-specific words or phrases known to the system. An implementation of this work forms a critical portion of the knowledge acquisition component of our Transportable English-Language Interface (TELl), which answers English questions about tabular (first normal-form) data files and runs on a Symbolics Lisp Machine. However, our techniques enable the design of customization modules that are largely independent of the syntactic and retrieval components of the specific system they supply information to. In addition to its obvious practical value, this area of research is important because it requires careful attention to the formalisms used by a natural language system and to the interactions among the modules based on those formalisms. 1. Introduction In constructing the Transportable English- Language Interface system (TELI). we have sought to respond to problems of both an applied and a scientific nature. Concerning the applied side of computational linguistics, we seek to redress the fact that many natural language prototypes, despite their sophistication and even their robustness, have fallen into disuse because of failures (1) to make known to users exactly what inputs are allowed (e.g. what words and phrases are defined) and (2) to provide capabilities that meet the precise needs of a given user or group of users (e.g. appropriate vocabulary, syntax. and semantics). Since experience has shown that neither users nor svstem designers can predict in advance all the words, phrases, and associated meanings that will arise in accessing a given database (cf. Tennant. 1979). we have sought to make TELl "transportable" in an extreme sense, where customizations may be performed (1) by end users, as opposed to the system designers, and (2) at any time during the processing of English sentences, rather than requiring a complete customization before English processing may occur. In addition to the potential practical benefits of a user-customized interface, we feel that well- conceived transportability projects can make useful scientific contributions to computational linguistics since single-domain systems and, to a lesser extent, systems adapted over weeks or months by their designers, afford opportunities to circumvent, rather than squarely address, important issues concerning (a) the precise nature of the formalisms the system is designed around, and (b) the interactions among system modules. Although customization efforts offer no guarantee against ad-hoc design or sloppy implementation, problems of the type mentioned above are less likely to go unnoticed when dealing with a system whose domain-specific information is supplied at run-time, especially when that information is being provided by the actual users of the system. By way of overview, we note that the TELI system derives from previous work on the LDC project, as documented in Ballard (1982), Ballard (1984), Ballard, Lusth and Tinkham (1984). and Ballard and Tinkham (1984). The initial prototype of …

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