Douglas E. Appelt

TEAM: an experiment in the design of transportable natural-language interfaces

Abstract This article describes TEAM, a transportable natural-language interface system. TEAM was constructed to test the feasibility of building a natural-language system that could be adapted to interface with new databases by users who are not experts in natural-language processing. An overview of the system design is presented, emphasizing those choices that were imposed by the demands of transportability. Several general problems of natural-language processing that were faced in constructing the system are discussed, including quantifier scoping, various pragmatic issues, and verb acquisition. TEAM is compared with several other transportable systems; this comparison includes a discussion of the range of natural language handled by each as well as a description of the approach taken to achieving transportability in each system.

Gemini: a natural language system for spoken-language understanding

Gemini is a natural language understanding system developed for spoken language applications. This paper describes the details of the system, and includes relevant measurements of size, efficiency, and performance of each of its sub-components in detail.

SRI International FASTUS system: MUC-6 test results and analysis

SRI International participated in the MUC-6 evaluation using the latest version of SRIs FASTUS system [1]. The FASTUS system was originally developed for participation in the MUC-4 evaluation [3] in 1992, and the performance of FASTUS in MUC-4 helped demonstrate the viability of finite state technologies in constrained natural-language understanding tasks. The system has undergone significant revision since MUC-4, and it is safe to say that the current system does not share a single line of code with the original. The fundamental ideas behind FASTUS, however, are retained in the current system: an architecture consisting of cascaded finite state transducers, each providing an additional level of analysis of the input, together with merging of the final results.

Planning english referring expressions

Abstract This paper describes a theory of language generation based on planning. To illustrate the theory, the problem of planning referring expressions is examined in detail. A theory based on planning makes it possible for one to account for noun phrases that refer, that inform the hearer of additional information, and that are coordinated with the speakers physical actions to clarify his communicative intent. The theory is embodied in a computer system called kamp , which plans both physical and linguistic actions, given a high-level description of the speakers goals.

GEMINI: A NATURAL LANGUAGE SYSTEM FOR SPOKEN-LANGUAGE UNDERSTANDING

The demands on a natural language understanding system used for spoken language differ somewhat from the demands of text processing. For processing spoken language, there is a tension between the system being as robust as necessary, and as constrained as possible. The robust system will a t tempt to find as sensible an interpretation as possible, even in the presence of performance errors by the speaker, or recognition errors by the speech recognizer. In contrast, in order to provide language constraints to a speech recognizer, a system should be able to detect that a recognized string is not a sentence of English, and disprefer that recognition hypothesis from the speech recognizer. If the coupling is to be tight, with parsing and recognition interleaved, then the parser should be able to enforce as many constraints as possible for partial utterances. The approach taken in Gemini is to tightly constrain language recognition to limit overgeneration, but to extend the language analysis to recognize certain characteristic patterns of spoken utterances (but not generally thought of as part of grammar) and to recognize specific types of performance errors by the speaker.

SRI's experience with the ATIS evaluation

SRI International participated in the June 1990 Air Travel Information System (ATIS) natural-language evaluation. This report briefly describes the system that SRI used in the evaluation, analyzes SRIs results, and makes some recommendations for changes in the database structure and data collection system to be used for future ATIS evaluations.

Weighted abduction for plan ascription

We describe an approach to abductive reasoning calledweighted abduction, which uses inference weights to compare competing explanations for observed behavior. We present an algorithm for computing a weighted-abductive explanation, and sketch a model-theoretic semantics for weighted abduction. We argue that this approach is well suited to problems of reasoning about mental state. In particular, we show how the model of plan ascription developed by Konolige and Pollack can be recast in the framework of weighted abduction, and we discuss the potential advantages and disadvantages of this encoding.

THE COMMON PATTERN SPECIFICATION LANGUAGE

This paper describes the Common Pattern Specification Language (CPSL) that was developed during the TIPSTER program by a committee of researchers from the TIPSTER research sites. Many information extraction systems work by matching regular expressions over the lexical features of input symbols. CPSL was designed as a language for specifying such finite-state grammars for the purpose of specifying information extraction rules in a relatively system-independent way. The adoption of such a common language would enable the creation of shareable resources for the development of rule-based information extraction systems.

FASTUS: a system for extracting information from text

FASTUS is a (slightly permuted) acronym for Finite State Automaton Text Understanding System. It is a system for extracting information from free text in English (Japanese is under development), for entry into a database, and potentially for other applications. It works essentially as a set of cascaded, nondeterministic finite state automata.

A template matcher for robust NL interpretation

In this paper, we describe the Template Matcher, a system built at SRI to provide robust natural-language interpretation in the Air Travel Information System (ATIS) domain. The system appears to be robust to both speech recognition errors and unanticipated or difficult locutions used by speakers. We explain the motivation for the Template Matcher, describe in general terms how it works in comparison with similar systems, and examine its performance. We discuss some limitations of this approach, and sketch a plan for integrating the Template Matcher with an analytic parser, which we believe will combine the advantages of both.