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Rhetorical Structure Theory: Description and Construction of Text Structures

IP.com Disclosure Number: IPCOM000128665D
Original Publication Date: 1986-Dec-31
Included in the Prior Art Database: 2005-Sep-16
Document File: 10 page(s) / 35K

Publishing Venue

Software Patent Institute

Related People

William C. Mann: AUTHOR [+4]

Abstract

Rhetorical Structure Theory (RST) is a theory of text structure that is being extended to serve as a theoretical basis for computational text planning. Text structures in RST are hierarchic, built on small patterns called schemas. The schemas which compose the structural hierarchy of a text describe the functions of the parts rather than their form characteristics. Relations between text parts, comparable to conjunctive relations, are a prominent part of RST's definitional machinery. Recent work has put RST onto a new definitional basis. This paper details the current status of descriptive RST, along with efforts to create a constructive version for use as a basis for programming a text planner.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Rhetorical Structure Theory: Description and Construction of Text Structures

William C. Mann USC Information Sciences Institute Marina del Rey, California, USA

Sandra A. Thompson University of California at Santa Barbara Santa Barbara, California, USA

Presented. at the Third International Workshop on Text Generation Nijmegen, The Netherlands

Abstract

Rhetorical Structure Theory (RST) is a theory of text structure that is being extended to serve as a theoretical basis for computational text planning. Text structures in RST are hierarchic, built on small patterns called schemas. The schemas which compose the structural hierarchy of a text describe the functions of the parts rather than their form characteristics. Relations between text parts, comparable to conjunctive relations, are a prominent part of RST's definitional machinery.

Recent work has put RST onto a new definitional basis. This paper details the current status of descriptive RST, along with efforts to create a constructive version for use as a basis for programming a text planner.

1 The Roots of Rhetorical Structure Theory

Rhetorical Structure Theory (RST) has been developed as a basis for text generation, specifically for planning large texts of diverse kinds. It currently exists in a well elaborated form as a descriptive theory, and in a more rudimentary form as a constructive theory based on the descriptive theory.' This paper, designed as a workshop paper, presents an overview and status report, showing the predominant general cases and passing over some of the details and exceptions. (Other papers attempt a much more precise account.)

iRhetorical Structure Theory was initially defined by the authors and Christian Matthiessen ; Barbara Fox, Cecilia Ford, and others have made important contributions. It has been influenced significantly by Grimes 751 and [McKeown 85]. (Mann & Thompson 861, (Mann 841 and [Mann & Thompson 85] are our principal earlier papers on RST. [Mann & Thompson 87] describes its relations to other theories in some detail. The support of the National Science Foundation and the Air Force Office of Scientific Research are gratefully acknowledged; the opinions in this paper are solely the authors'.

2 Principal Mechanisms of Descriptive RST

RST describes a text by assigning a structure to it. Prior to analysis, a text is broken into units of a size that is convenient for the analyst's purposes. (Independent clauses are normally the smallest units; however, larger units may be chosen for larger texts.) These units function as

University of Southern California Page 1 Dec 31, 1986

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Rhetorical Structure Theory: Description and Construction of Text Structures

terminal nodes in an RST structure -- which is a tree that covers the entire text. In this way an RST structure resembles a conventional sentence structure, but the resemblance is superficial.

The RST analysis is built out of...