Rules of conversation are given that specify what can follow what. A system for deciding what makes a reasonable subject for a conversation is shown. Topics are discussed and rules for topic shift are presented.

A major goal of this work is to specify some steps of the process by which participants maintain coherency in their conversations.The underlying element of the analysis is a construct called a “context space.” Roughly, a group of utterances that refers to a single issue or episode forms the basis for a context space. Superficially, a conversation is a sequence of utterances; at a deeper level it is a structured entity whose utterances can be parsed into hierarchically related context spaces.As (...) a conversation proceeds, each conversant builds a discourse model that includes the conversation's context space structure, a notion of the present discourse topic, and a list of items being focused upon. Conversational coherency depends upon a lack of conflict between the respective models of the participants. Conflicts are prevented by speakers following high level syntactic and semantic relational rules that enable listeners to identify their discourse models. These rules, given in the study, are highly integrated with the view of conversation presented here—a hierarchy of related context spaces. (shrink)