Joseph Downs, Han Reichgelt, Nigel Shadbolt
AI planning systems must be able to update their internal model of the domain in order to determine the effects of a possible action. The most widely used update method is the STRIPS operator. STRIPS operators are extremely efficient. However, the use of STRIPS operators requires that one specify all the consequences of an action beforehand. This becomes almost impossible for complex domains. Work by Pednault (1989) and Wilkins (1988) overcomes the problems associated with ordinary STRIPS operators by enhancing them with context-dependent effects and demons respectively. In this paper we describe a modelling procedure which can incorporate both these features. Moreover, the update method is automatically derived from an axiomatisation of the domain in temporal calculus. This allows the system designer great flexibility in choosing the trade- off point between representational expressivity against computational speed.