Planning coherent multisentential text

Though most text generators are capable of simply stringing together more than one sentence, they cannot determine which order will ensure a coherent paragraph. A paragraph is coherent when the information in successive sentences follows some pattern of inference or of knowledge with which the hearer is familiar. To signal such inferences, speakers usually use relations that link successive sentences in fixed ways. A set of 20 relations that span most of what people usually say in English is proposed in the Rhetorical Structure Theory of Mann and Thompson. This paper describes the formalization of these relations and their use in a prototype text planner that structures input elements into coherent paragraphs.