COMPLEXITY, DECIDABILITY AND UNDECIDABILITY RESULTS FOR DOMAIN-INDEPENDENT PLANNING

In this paper, we examine how the complexity of domain-independent pla nning with STRIPS-style operators depends on the nature of the plannin g operators. We show conditions under which planning is decidable and undecidable. Our results on this topic solve an open problem posed by Chapman (1987), and clear up some difficulties with his undecidability theorems. For those cases where planning is decidable, we explain how the time complexity varies depending on a wide variety of conditions: whether or not function symbols are allowed; whether or not delete li sts are allowed; whether or not negative preconditions are allowed; wh ether or not the predicates are restricted to be propositional (i.e., O-ary); whether the planning operators are given as part of the input to the planning problem, or instead are fixed in advance. whether or n ot the operators can have conditional effects.