A Complete Epistemic Planner without the Epistemic Closed World Assumption

Planning with epistemic goals has received attention from both the dynamic logic and planning communities. In the single-agent case, under the epistemic closed-world assumption (ECWA), epistemic planning can be reduced to contingent planning. However, it is inappropriate to make the ECWA in some epistemic planning scenarios, for example, when the agent is not fully introspective, or when the agent wants to devise a generic plan that applies to a wide range of situations. In this paper, we propose a complete single-agent epistemic planner without the ECWA. We identify two normal forms of epistemic formulas: weak minimal epistemic DNF and weak minimal epistemic CNF, and present the progression and entailment algorithms based on these normal forms. We adapt the PrAO algorithm for contingent planning from the literature as the main planning algorithm and develop a complete epistemic planner called EPK. Our experimental results show that EPK can generate solutions effectively for most of the epistemic planning problems we have considered including those without the ECWA.