Intentions and Rational Commitment

Intentions, an integral part of the mental state of an agent, play an important role in determining the behaviour of rational agents as they seek to attain their goals. In this paper, a formalization of intention based on rational commitment is presented. The formalization is based on a branching-time possible-worlds semantics for beliefs, goals, and intentions, upon which conditions are imposed to capture the notion of rational commitment. It is shown how the formalism realizes many of the important elements of Bratman's theory of intention. In particular, the notion of intention developed here has equal status with the notions of belief and desire, and cannot be reduced to these concepts. A number of di erent rational agents are modeled by imposing certain conditions on the persistence of an agent's beliefs, goals, and intentions. Finally, the formalism is compared with Bratman's theory of intention, Cohen and Levesque's formalization of intentions, and a situated AI system (the Procedural Reasoning System) that reasons about intentions.