Formalizing Actions in Branching Time Model Theoretic Considerations

The formalization of actions is essential to AI Several approaches have been pro posed over the years However most ap proaches concentrate on the causes and ef fects of actions but do not give general characterizations of actions themselves A useful formalization of actions would be based on a general possibly nondiscrete model of time that allows branching to capture agents choices A good formal ization would also allow actions to be of arbitrary duration and would permit mul tiple agents to act concurrently We de velop a branching time framework that al lows great exibility in how time and ac tion are modeled We motivate and for malize several coherence constraints on our models which capture some nice intuitions and validate some useful inferences relat ing actions with time