As said above, the representation of actions and formalisms/logics to reason with them are very central to AI and particularly the field of KR. One of the main problems that one encounters in the literature on reasoning about actions in AI, and much more so than in mainstream computer science, is the discovery of the so-called frame problem (McCarthy and Hayes 1969). Although this problem has been generalized by philosophers such as Dennett (1984) to a general problem of relevance and salience o