Validating plans in the context of processes and exogenous events

Complex planning domains push the boundaries of the expressive power of planning domain modelling languages. Recent extensions to the standard planning languages have included expressions for temporal, metric and resource structures. Other work has also considered how process models can be incorporated into domain models. In this paper we consider the problem of expressing and validating models containing events which are triggered as a consequence of the action of physical processes. We focus, primarily, on the validation of plans in the context of exogenous events, discussing the modelling, semantic and implementation issues that arise. Events impact not only on plans but on domain models as a whole and we also consider the problems that arise in considering the validation of event structures in domain models.