A Model of Revision in Natural Language Generation

A MODEL OF REVISION IN NATURAL LANGUAGE GENERATION Marie M. Vaughan David D. McDonald Department of Computer and Information Science University of Massachusetts Amherst, Massachusetts 01003 ABSTRACT We outline a model of generation with revision, focusing on improving textual coherence. We argue that high quality text is more easily produced by iteratively revising and regenerating, as people do, rather than by using an architecturally more complex single pass generator. As a general area of study, the revision process presents interesting problems: Recognition of flaws in text requires a descriptive theory of what constitutes well written prose and a parser which can build a representation in those terms. Improving text requires associating flaws with strategies for improvement. The strategies, in turn, need to know what adjustments to the decisions made during the initial generation will produce appropriate modifications to the text. We compare our treatment of revision with those of Mann and Moore (1981), Gabriel (1984), and Mann (1983). 1. INTRODUCTION / Revision is a large part of the writing process for people. This is one respect in which writing differs from speech. In ordinary conversation we do not rehearse what we are going to say; however, when writing a text which may be used more than once by an audience which is not present, we use a multipass system of writing and rewriting to produce optimal text. By reading what we write, we seem better able to detect flaws in the text and see new options for improvement. Why most people are not able to produce optimal text in one pass is an open and interesting question. Flower and Hayes (1980) and Collins and Gentner (1980) suggest that writers are unable to juggle the excessive number of simultaneous demands and constraints which arise in producing well written text. Writers must concentrate not only on expressing content and purpose, but also on the discourse conventions of written prose: the constraints on sentence, paragraph, and text structure which are designed to make texts more readable. Successive iterations of writing and revising may allow the writer to reduce the number of considerations demanding attention at a given time. The developers of natural language generation systems must also address the problem of how to produce high quality text. Most systems today concentrate on the production of dialogs or commentaries, where the texts are generally short and the coherence is strengthened by nonlinguistic context. However, in written documents coherence must be maintained by the text alone. In addition, written text must anticipate the questions of its readers. The text must be clear and well organized so that the reader may follow the points easily, and it must be concise and interesting so as to hold the reader's attention. These considerations place greater demands on a generation system. Most natural language generation systems generate in a single pass with no revision. A drawback of this approach is that the information necessary for decision making must be structured so that at any given point the generator has …

Content truncated to 500 words