The STRICT assumption: a propositional approach to change

Abstract There are two main approaches to reasoning about change, the logicist—relying on the assumption that if actions and situations can be represented as propositions, then reasoning about change is nothing but classical reasoning— and the non-logicist—based on the assumption that the effects of actions are circumscribed to the ones explicitly stated in the corresponding operator descriptions, everything else remaining unaffected by change (STRIPS assumption). Both of these approaches have pitfalls: the former rely on associating the state of the world with a situation variable, which implies the need to write down frame axioms, stating what characteristics of the world are not affected by change. The latter assumes that the only characteristics of the world that can change are those which correspond to direct observation and not those derived using inference. That is to say, operators must be characterized using only ‘basic’ or ‘primitive’ predicates. The direct consequences of these pitfalls are, on...