DEL planning and some tractable cases Benedikt Löwe, Eric Pacuit, Andreas Witzel Abstract: We describe the planning problem within the framework of dynamic epistemic logic (DEL), considering the tree of sequences of events as the underlying structure. In general, the DEL planning problem is computationally difficult to solve. On the other hand, a great deal of fruitful technical advances have led to deep insights into the way DEL works, and these can be exploited in special cases.We present a few properties that will lead to considerable simplications of the DEL planning problem and apply them in a toy example. Keywords: DEL planning; Thief; DEL