Erol, KutluhanNau, D.S.Subrahmanian, V.S.In this paper, we examine how the complexity of domain- independent planning with STRIPS-like operators depends on the nature of the planning operators.<P>We show conditions under which planning is decidable and undecidable. Our results on this topic solve an open problem posed by Chapman [4], and clear up some difficulties with his undecidability theorems.<P>For those cases where planning is decidable, we show how the time complexity varies depending on a wide variety of conditions:  whether or not function symbols are allowed; whether or not delete lists are allowed; whether or not negative preconditions are allowed; whether or not the predicates are restricted to be propositional (i.e., 0-ary); whether the planning operators are given as part of the input to the planning problem, or instead are fixed in advance.<P>en-UScomputational complexitySystems IntegrationTechnical Report