Showing papers in "Computational Linguistics in 1980"

A plan-based analysis of indirect speech acts

Abstract: We propose an account of indirect forms of speech acts to request and inform based on the hypothesis that language users can recognize actions being performed by others, infer goals being sought, and cooperate in their achievement. This cooperative behaviour is independently motivated and may or may not be intended by speakers. If the hearer believes it is intended, he or she can recognize the speech act as indirect; otherwise it is interpreted directly. Heuristics are suggested to decide among the interpretations.

Cascaded ATN grammars

Abstract: A generalization of the notion of ATN grammar, called a cascaded ATN (CATN), is presented. CATN's permit a decomposition of complex language understanding behavior into a sequence of cooperating ATN's with separate domains of responsibility, where each stage (called an ATN transducer) takes its input from the output of the previous stage. The paper includes an extensive discussion of the principle of factoring -- conceptual factoring reduces the number of places that a given fact needs to be represented in a grammar, and hypothesis factoring reduces the number of distinct hypotheses that have to be considered during parsing.

An integrated understander

Abstract: A new type of natural language parser is presented The idea behind this parser is to map input sentences into the deepest form of the representation of their meaning and inferences, as is appropriate The parser is not distinct from an entire understanding system It uses an integrated conception of inferences, scripts, plans, and other knowledge to aid in the parse Furthermore, it does not attempt to parse everything it sees Rather, it determines what is most interesting and concentrates on that, ignoring the rest

Slot grammars

Abstract: This paper presents an approach to natural language grammars and parsing in which slots and rules for filling them play a major role. The system described provides a natural way of handling a wide variety of grammatical phenomena, such as WH-movement, verb dependencies, and agreement.

Some Representational Issues in Default Reasoning

Abstract: Although most commonly occurring default rules are normal when I viewed in isolation, they can interact with each other in ways that lead to the derivation of anomalous default assumptions. In order to deal with such anomalies it is necessary to re-represent these rules, in some cases by introducing non-normal defaults. The need to consider such potential interactions leads to a new concept of integrity, distinct from the conventional integrity issues of first order data bases. .br The non-normal default rules required to deal with default interactions all have a common pattern. Default theories conforming to this pattern are considerably more complex than normal default theories. For example, they need not have extensions, and they lack the property of semi-monotonicity. .br Current semantic network representations fail to reason correctly with defaults. However, when viewed as indexing schemes on logical formulae, networks can be seen to provide computationally feasible heuristics for the consistency checks required by default reasoning.

Responding intelligently to unparsable inputs

Abstract: All natural language systems are likely to receive inputs for which they are unprepared The system must be able to respond to such inputs by explicitly indicating the reasons the input could not be understood, so that the user will have precise information for trying to rephrase the input If natural language communication to data bases, to expert consultant systems, or to any other practical system is to be accepted by other than computer personnel, this is an absolute necessityThis paper presents several ideas for dealing with parts of this broad problem One is the use of presupposition to detect user assumptions The second is relaxation of tests while parsing The third is a general technique for responding intelligently when no parse can be found All of these ideas have been implemented and tested in one of two natural language systems Some of the ideas are heuristics that might be employed by humans; others are engineering solutions for the problem of practical natural language systems

Toward natural language computation

Abstract: A computer programming system called the "Natural Language Computer" (NLC) is described which allows a user to type English commands while watching them executed on sample data appearing on a display screen. Direct visual feedback enables the user to detect most misinterpretation errors as they are made so that incorrect or ambiguous commands can be retyped or clarified immediately. A sequence of correctly executed commands may be given a name and used as a subroutine, thus extending the set of available operations and allowing larger English-language programs to be constructed hierarchically. In addition to discussing the transition network syntax and procedural semantics of the system, special attention is devoted to the following topics: the nature of imperative sentences in the matrix domain; the processing of non-trivial noun phrases; conjunction; pronominals; and programming constructs such as "if", "repeat", and procedure definition.

Computing story trees

Abstract: A theory of understanding (parsing) texts as a process of collecting simple textual propositions into thematically and causally related units is described, based on the concept of macrostructures as proposed by Kintsch and van Dijk. These macrostructures are organized into tree hierarchies, and their interrelationships are described in rule-based story grammars related to the Kowalski logic based on Horn clauses. A procedure for constructing and synthesizing such trees from semantic network forms is detailed. The implementation of this procedure is capable of understanding and summarizing any story it can generate using the same basic control structure.

Characterizing indirect speech acts

Abstract: This paper presents the core of a descriptive theory of indirect speech acts, i.e. utterances in which one speech act form is used to realize another, different, speech act. The proposed characterization of indirect speech acts is based on principles of goal formation, viewed in the context of a general structural model of action. The model of action is used to develop rules that characterize a large number of indirect speech act forms. Computational implications of the theory are discussed.

A parsing algorithm that extends phrases

Abstract: It is desirable for a parser to be able to extend a phrase even after it has been combined into a larger syntactic unit. This paper presents an algorithm that does this in two ways, one dealing with "right extension" and the other with "left recursion". A brief comparison with other parsing algorithms shows it to be related to the left-corner parsing algorithm, but it is more flexible in the order that it permits phrases to be combined. It has many of the properties of the sentence analyzers of Marcus and Riesbeck, but is independent of the language theories on which those programs are based.