Marcia C. Linebarger

Recovering implicit information

This paper describes the SDC PUNDIT, (Prolog UNDerstands Integrated Text), system for processing natural language messages. PUNDIT, written in Prolog, is a highly modular system consisting of distinct syntactic, semantic and pragmatics components. Each component draws on one or more sets of data, including a lexicon, a broad-coverage grammar of English, semantic verb decompositions, rules mapping between syntactic and semantic constituents, and a domain model.This paper discusses the communication between the syntactic, semantic and pragmatic modules that is necessary for making implicit linguistic information explicit. The key is letting syntax and semantics recognize missing linguistic entities as implicit entities, so that they can be labelled as such, and reference resolution can be directed to find specific referents for the entities. In this way the task of making implicit linguistic information explicit becomes a subset of the tasks performed by reference resolution. The success of this approach is dependent on marking missing syntactic constituents as elided and missing semantic roles as ESSENTIAL so that reference resolution can know when to look for referents.

Agrammatism as Evidence About Grammar

A variety of experimental paradigms has yielded surprisingly fine-grained evidence about the kinds of syntactic information to which agrammatic aphasics are sensitive. This paper contrasts three accounts of agrammatism which draw quite different conclusions about the implications of this disorder for normal function: the chain-disruption, trade-off, and mapping hypotheses. Counterarguments to the chain disruption and trade-off hypotheses are presented, and it is argued that agrammatism provides considerable support for the modularity of syntax but provides no evidence more specific than that regarding the psychological reality of government binding theory vis-à-vis other current theories of grammar.

The Status of the Syntactic Deficit Theory of Agrammatism

Publisher Summary This chapter discusses the importance of Syntactic Deficit Theory of Agrammatism. It presents three different descriptions of an SDTA, all contributing toward categorization of the agrammatic pathology (Language System minus Syntactic Component) but disagreeing from one another in the characteristics they ascribe to the syntactic component. An uncontroversial assertion is that there is a subset of aphasics who speak with a lot of effort along with phonetic distortion (Brocas aphasics), of whom it can be said that the sentences they speak have minimum syntactic structure, if any. The next uncontroversial is that agrammatic aphasies are not sensitive toward syntactic structure of sentences. However, it can be said that the problem does not lie in aspects of sentence interpretation that involve lexical semantics and that there is no evidence to prove that agrammatics have difficulty understanding sentences where lexical content alone constrains meaning.

Grammatical Encoding in Aphasia: Evidence from a “Processing Prosthesis”

Agrammatic aphasia is characterized by severely reduced grammatical structure in spoken and written language, often accompanied by apparent insensitivity to grammatical structure in comprehension. Does agrammatism represent loss of linguistic competence or rather performance factors such as memory or resource limitations? A considerable body of evidence supports the latter hypothesis in the domain of comprehension. Here we present the first strong evidence for the performance hypothesis in the domain of production: an augmentative communication system that markedly increases the grammatical structure of agrammatic speech while providing no linguistic information, functioning merely to reduce on-line processing demands.

Beyond class A: a proposal for automatic evaluation of discourse

The DARPA Spoken Language community has just completed the first trial evaluation of spontaneous query/response pairs in the Air Travel (ATIS) domain.1 Our goal has been to find a methodology for evaluating correct responses to user queries. To this end, we agreed, for the first trial evaluation, to constrain the problem in several ways:Database Application: Constrain the application to a database query application, to ease the burden of a) constructing the back-end, and b) determining correct responses;

Computer-based training of language production: An exploratory study

Described here is an exploratory study designed to assess the feasibility of two new technologies for the treatment of aphasic sentence processing disorders: a computerised therapy programme incorporating natural language understanding (NLU), software which enables the computer to understand spoken utterances; and an augmentative communication system functioning primarily as a “processing prosthesis”, which allows patients to construct spoken sentences piecemeal and maintain elements already produced. Five agrammatic patients participated in a series of studies incorporating one or both of these technologies, and made language gains (ranging from modest to quite marked) following independent home use of the software. We hypothesise that the therapy and communication systems played complementary roles in this process, with the former training and/or priming specific grammatical structures and the latter providing the processing support necessary for these structures to be practised under normal conditions.

The PUNDIT natural-language processing system

The authors describe the PUNDIT (Prolog Understanding of Integrated Text) text-understanding system, which is designed to analyze and construct representations of paragraph-length text. PUNDIT is implemented in Quintus Prolog, and consists of distinct lexical, syntactic, semantic, and pragmatic components. Each component draws on one or more sets of data, including a lexicon, a broad-coverage grammar of English, semantic verb decompositions, rules mapping between syntactic and semantic constituents, and a domain model. Modularity, careful separation of declarative and procedural information, and separation of domain-specific and domain-independent information all contribute to a system which is flexible, extensible and portable. Versions of PUNDIT are now running in five domains, including four military and one medical.<<ETX>>

SENTENCE FRAGMENTS REGULAR STRUCTURES

This paper describes an analysis of telegraphic fragments as regular structures (not errors) handled by minimal extensions to a system designed for processing the standard language. The modular approach which has been implemented in the Unisys natural language processing system PUNDIT is based on a division of labor in which syntax regulates the occurrence and distribution of elided elements, and semantics and pragmatics use the systems standard mechanisms to interpret them.

Management and evaluation of interactive dialog in the air travel domain

This paper presents the Unisys Spoken Language System, as applied to the Air Travel Planning (ATIS) domain. This domain provides a rich source of interactive dialog, and has been chosen as a common application task for the development and evaluation of spoken language understanding systems. The Unisys approach to developing a spoken language system combines SUMMIT (the MIT speech recognition system [6]), PUNDIT (the Unisys language understanding system [3]) and an Ingres database of air travel information for eleven cities and nine airports (the ATIS database). Access to the database is mediated via a general knowledge-base/database interface (the Intelligent Database Server [4]). To date, we have concentrated on the language understanding and database interface components.

Neuropsychological Evidence for Linguistic Modularity

Language disorders resulting from brain damage provide a unique perspective on language processing in the normal case. In this paper, I wish to argue that language pathology may provide considerable support for one set of claims about language processing: the thesis of linguistic modularity. In particular, I will review the neuropsychological evidence that bears most directly upon the claim that syntactic structure is computed by an autonomous processing module.