Answer Set Planning under Action Costs

More recently, planning based on answer set programming has been proposed as an approach towards realizing declarative planning systems. In this paper, we present the language K , which extends the declarative planning language K by action costs and provides the notion of admissible and optimal plans, which are plans whose overall action costs are within a given limit resp. minimum over all plans (i.e., cheapest plans). As we demonstrate, this novel language allows for expressing several nontrivial planning tasks in an elegant way. Furthermore, it flexibly allows for representing planning problems under other optimality criteria, such as computing “shortest” plans (with the least number of steps), and refinement combinations of cheapest and fastest plans. We study complexity aspects of the language K and provide a transformation to logic programs, such that planning problems are solved via answer set programming. Furthermore, we report experimental results on selected problems. Our experience is encouraging and provides further evidence to the view that answer set planning may be a valuable approach to expressive planning systems in which intricate planning problems can be naturally specified and decently solved.