What is the expressive power of disjunctive preconditions?

Abstract

While there seems to be a general consensus about the ex-pressive power of a number of language features in planning formalisms, one can find many difierent statements about the expressive power of disjunctive preconditions. Using the\compilability framework," we show that preconditions in conjunctive normal form add to the expressive po-wer of propositional strips, which confirms a conjecture by Backstrom. Further, we show that preconditions in conjunctive normal form do not add any expressive power once we have conditional effects.