Iterated Belief Change and Exogeneous Actions in the Situation Calculus

We present a novel theory of action and change capable of dealing with discord between an agent's beliefs and the results of its sensing. Previous work by Scherl and Levesque [9] and Shapiro et al. [10] have given accounts of iterated belief update and revision, and the ability to deal with mistaken beliefs. However, they assume that all actions, including exogenous actions beyond the agent's control, are accessible to the agent for the purposes of reasoning. Our approach abandons this idealistic stance and allows the agent to hypothesise the occurrence of exogenous actions to account for any discrepancy between belief and sensing.