This project aims to develop a formal and implementable theory of the communicative interactions that can occur within a man- machine dialog. It will develop a plan-based model of the interaction - explicity representing the differing beliefs of the system and the user, as well as their mutually shared beliefs arising from the dialog, and representing the sentences in the dialog explicitly as actions - both as speech acts reflecting immediate intentions, and as discourse acts, signalling the structure of the dialog. The goal is to develop a domain- independent model of dialog interaction, focusing on those aspects that allow the system and user to monitor how well the dialog is understood. In particular, the intent is to account for the prevalent acknowledgement behavior in dialog, and to provide a general account of clarifications and correction subdialogs. The work also will examine how the planning model affects the actual interpretation of the sentences in the dialog, concentrating on the effects the model has on speech act interpretation, and the interpretation of tense and aspect, and the generic/specific distinction. As a result, the plan-based approach to language will be brought into much closer correspondence to the actual linguistic behavior apparent in natural dialogs.
