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An Experimental Parser for Systemic Grammars

IP.com Disclosure Number: IPCOM000128688D
Original Publication Date: 1988-Dec-31
Included in the Prior Art Database: 2005-Sep-16
Document File: 8 page(s) / 31K

Publishing Venue

Software Patent Institute

Related People

Robert T. Kasper: AUTHOR [+3]

Abstract

Many computational linguists have found systemic grammar (SG) to be quite useful, because it provides an explicit representation of features that determine how a sentence functions in the context of communication. SG has been used directly as the basis for several computer text generation programs (Mann 821, but it has only been used indirectly for computational parsers. Winograd used principles from SG in designing SHRDLU [Winograd 721, a successful natural language understanding program, but his program did not contain an explicit representation of the grammar's system network. Instead, he used a special purpose programming language to encode grammatical knowledge in a procedural form tailored specifically to the language understanding task. Another procedural implementation of SG was developed by McCord [McCord 77). Both of these methods require a significant programming step before a parser could be produced for a different grammar. Our goal has been to develop a general parsing method using a declarative representation of SG, and to determine to what extent a grammar that is adequate for text generation can also be used for text analysis. Our parser has been developed and tested using Nigel (Mann 831, a large grammar of English that has previously been used as part of a text generation system. Systemic linguistics builds on the foundation of Halliday's concept of the system network [Halliday ?61. A systemic grammar is organized around choices between grammatical features that reflect the structure and content of a constituent. Each choice between features is called a system. Thus, a systemic grammar has two major components: 1. a system network of feature choices, and 2. structural realization statements corresponding to each feature. The feature choices define the options available to be expressed in a language, and may be regarded as "hooks" into a semantic component. The realization statements determine the con-stituent structure. There are realization statements to declare the presence of constituents, con-flate constituents, specify feature constraints on constituents, and specify ordering constraints among constituents.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

An Experimental Parser for Systemic Grammars

Robert T. Kasper

ISI Reprint Series ISIIRS-88-212 June 1988 University of Southern California

Reprinted from the Proceedings of the 12th International Conference on Computational Linguistics, held 22-27 august 1988 in Budapest, Hungary. INFORMATION SCIENCES INSTITUTE 213/822-1511 9676 Admiralty Way/Marina del Rey/California 90292-6695

This research is supported in part by the Defense Advanced Research Projects Agency under Contrail No. MDA903-81-C-0335 and in part by the Air Force Office of Scientific Research under Contract No. F49620-87-C-0005. Views and conclusions contained in this report are the author's and should not be interpreted as representing the official opinion or policy of DARPA, AFOSR, the U.S. Government, or any person or agency connected with them.

IS l Reprint Series This report is one in a series of reprints of articles and papers written by ISI research staff and published in professional journals and conference proceedings. For a complete list of ISI reports, write to

Document Distribution USC/Information Sciences Institute

4676 Admiralty Way Marina del Rey, CA 90292-6695 USA

1 Introduction

Many computational linguists have found systemic grammar (SG) to be quite useful, because it provides an explicit representation of features that determine how a sentence functions in the context of communication. SG has been used directly as the basis for several computer text generation programs (Mann 821, but it has only been used indirectly for computational parsers. Winograd used principles from SG in designing SHRDLU [Winograd 721, a successful natural language understanding program, but his program did not contain an explicit representation of the grammar's system network. Instead, he used a special purpose programming language to encode grammatical knowledge in a procedural form tailored specifically to the language understanding task. Another procedural implementation of SG was developed by McCord [McCord 77). Both of these methods require a significant programming step before a parser could be produced for a different grammar. Our goal has been to develop a general parsing method using a declarative representation of SG, and to determine to what extent a grammar that is adequate for text generation can also be used for text analysis. Our parser has been developed and tested using Nigel (Mann 831, a large grammar of English that has previously been used as part of a text generation system.

Systemic linguistics builds on the foundation of Halliday's concept of the system network [Halliday ?61. A systemic grammar is organized around choices between grammatical features that reflect the structure and content of a constituent. Each choice between features is called a system. Thus, a systemic grammar has two major components:

1. a system network of feature choices, and

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