tailieunhanh - Báo cáo khoa học: "THE EXPRESSION OF LOCAL RHETORICAL RELATIONS IN INSTRUCTIONAL TEXT*"

Given the prevalence of the use of rhetorical relations in the generation of text (Itovy, 1989; Moore and Paris, 1988; Scott and Souza, 1990), it is surprising how little work has actually been done on the grammatical realization of these relations. Most systems, based on Mann and Thompson's formulation of Rhetorical Structure Theory (Mann and Thompson, 1988), have adopted simplified solutions to their expression. If, for example, an action, X, and a purpose for that action, Y, must be expressed, a standard form such as "Do X in order to Y" will be generated. In reality, the purpose relation. | THE EXPRESSION OF LOCAL RHETORICAL RELATIONS IN INSTRUCTIONAL TEXT Keith Vander Linden Department of Computer Science University of Colorado Boulder co 80309-0430 Internet Iinden@ INTRODUCTION Given the prevalence of the use of rhetorical relations in the generation of text Hovy 1989 Moore and Paris 1988 Scott and Souza 1990 it is surprising how little work has actually been done on the grammatical realization of these relations. Most systems based on Mann and Thompson s formulation of Rhetorical Structure Theory Mann and Thompson 1988 have adopted simplified so- . lutions to their expression. If for example an action X and a purpose for that action Y must be expressed a standard form such as Do X in order to Y will be generated. In reality the purpose relation can be and is expressed in a myriad of different ways depending upon numerous functional considerations. Consider the following examples la Follow the steps in the illustration below for desk installation code 1 lb To install the phone on a desk follow the steps in the illustration below. lc Follow the steps in the illustration below for installing the phone on a desk. ld For the desk follow the steps in the illustration below. These examples of purpose expressions illustrate two issues of choice at the rhetorical level. First the purpose clauses phrases can occur either before or after the actions which they motivate. Second there are four grammatical forms to choose from all found in our corpus . In la we see a for prepositional phrase with a nominaliza-tion installation as the complement in lb a to infinitive form tnf in 1c a for preposition with a gerund phrase as a complement and This work was supported in part by NSF Grant IRI-9109859. 1 My convention will be to add a reference to the end of all examples that have come from our corpus indicating which manual they came from code and exc will stand for examples from the Code-a-Phone and Excursion manuals respectively Code-a-phone 1989 .