Proceedings of the Annual Meeting of the Cognitive Science Society

In multisentence texts, the order and interrelationships of sentence topics is of crucial importance if the reader is to understand easily. What makes paragraphs coherent? What strategies do people employ to control the presentation order and linking of material? Without a theory of coherence, text generation systems have little hope of producing acceptable texts. While various theories of text coherence have been developed, no single theory captures all the phenomena of human-generated paragraphs. In this paper we argue that the coherence of a paragraph does not result from the application of a single theory, but instead results from the cooperation of a number of different coherence strategies. W e illustrate this claim by showing how two very different theories about the planning of coherent text — 1) Rhetorical Structure Theory, based on structural and semantic relationships that hold between pieces of the text, and 2) Focus Trees, based on how the focus of attention shifts during discourse — can be used within a single system to complement each other to best advantage.