William C. Mann

Rhetorical Structure Theory : Toward a Functional Theory of Text Organization

Rhetorical Structure Theory is a descriptive theory of a major aspect of the organization of natural text. It is a linguistically useful methodfor describing natural texts, characterizing their Structure primarily in terms of relations that hold between parts of the text. This paper establishes a new definitional foundation for RST. The paper also examines three Claims ofRST: the predominance of nucleus/satellite structural pattems, the functional basis of hierarchy, and the communicative role oftext Structure.

Relational propositions in discourse

In addition to the propositions represented explicitly by independent clauses in a text, there are almost as many propositions, here called relational propositions, which arise (often implicitly) out of combinations of these clauses. The predicates of these propositions are members of a small set of general, highly recurrent relational predicates, such as “cause,” “justification,” and “solutionhood.” Often unsignalled, these relational propositions can be shown to be the basis for various kinds of inferences and to function as elements of communicative acts. Examining two natural texts, we see that the relational propositions involve every clause, and that they occur in a pattern of propositions which connects all of the clauses together. This examination also shows how the relational propositions are essential to the functioning of the text.

Rhetorical Structure Theory: Description and Construction of Text Structures

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.

Natural Language Generation in Artificial Intelligence and Computational Linguistics

One of the aims of Natural Language Processing is to facilitate .the use of computers by allowing their users to communicate in natural language. There are two important aspects to person-machine communication: understanding and generating. While natural language understanding has been a major focus of research, natural language generation is a relatively new and increasingly active field of research. This book presents an overview of the state of the art in natural language generation, describing both new results and directions for new research. The principal emphasis of natural language generation is not only to facili tate the use of computers but also to develop a computational theory of human language ability. In doing so, it is a tool for extending, clarifying and verifying theories that have been put forth in linguistics, psychology and sociology about how people communicate. A natural language generator will typically have access to a large body of knowledge from which to select information to present to users as well as numer of expressing it. Generating a text can thus be seen as a problem of ous ways decision-making under multiple constraints: constraints from the propositional knowledge at hand, from the linguistic tools available, from the communicative goals and intentions to be achieved, from the audience the text is aimed at and from the situation and past discourse. Researchers in generation try to identify the factors involved in this process and determine how best to represent the factors and their dependencies.

Discourse Structures for Text Generation

Text generation programs need to be designed around a theory of text organization. This paper introduces Rhetorical Structure Theory, a theory of text structure in which each region of text has a central nuclear part and a number of satellites related to it. A natural text is analyzed as an example, the mechanisms of the theory are identified, and their formalization is discussed. In a comparison, Rhetorical Structure Theory is found to be more comprehensive and more informative about text function than the text organization parts of previous text generation systems.

AN OVERVIEW OF THE NIGEL TEXT GENERATION GRAMMAR

Research on the text generation task has led to creation of a large systemic grammar of English, Nigel, which is embedded in a computer program. The grammar and the systemic framework have been extended by addition of a semantic stratum. The grammar generates sentences and other units under several kinds of experimental control.This paper describes augmentations of various precedents in the systemic framework. The emphasis is on developments which control the text to fulfill a purpose, and on characteristics which make Nigel relatively easy to embed in a larger experimental program.

Text generation: the problem of text structure

What is text generation?1 The long term view is that it is the process of creating a technology for building computer programs that can function as authors or speakers. I call this the long term view because in the text generation programs in existence today there is very little that deserves the title of “author” or “speaker.” Writing and speaking are rightly regarded as complex arts capable of high refinement and great intellectual achievement. In contrast, our programs reflect only fragments of the most basic skills.

Functions of language in two frameworks

AbstractSome of the most central problems in linguistics concern how language fills its characteristic roles: how it is useful, the nature and extent of its translatability, and the nature of the integrity of texts. Within linguistics there are many kinds of description that bear on such questions, one kind being the description of language in terms of its functions. Comparing these functional descriptions, the various descriptions do not all cover the same ground. Rather, each is quite partial, and appropriate ways to combine them into a more comprehensive account are not evident. It is hard to know wherein they conflict, wherein they agree, and where they simply speak of different things.This paper is part of an effort to relate various accounts. It is the first in a pair of papers that compare two particular accounts: Rhetorical Structure Theory and Systemic Linguistics.Rhetorical Structure Theory, initially formulated in 1983, describes texts in terms of functionally-defined relations that hold betwee...

The Anatomy of a Systemic Choice.

This paper presents a framework for expressing how choices are made in systemic grammars. Formalizing the description of choice processes enriches descriptions of the syntax and semantics of languages, and it contributes to constructive models of language use. There are applications in education and computation. The framework represents the grammar as a combination of systemic syntactic description and explicit choice processes, called “choice experts.” Choice experts communicate across the boundary of the grammar to its environment, exploring an external intention to communicate. The environments answers lead to choices and thereby to creation of sentences and other units, tending to satisfy the intention to communicate. The experts’ communicative framework includes an extension to the systemic notion of a function, in the direction of a more explicit semantics. Choice expert processes are presented in two notations, one informal and the other formal. The informal notation yields a grammar‐guided conver...

Why things are so bad for the computer-naive user

This paper is about peoples use of computers to get work done. Computers are tools that operate on symbols. Unlike many other tools, such as eggbeaters, telephones and automobiles, most people in our culture seem to regard computers as alien, mysterious and inherently difficult to use. While some of this view is based on mere hearsay, it is nonetheless held by many who have had some experience with computer systems.