The two faces of plan repair

Plan repair has two faces. Alternately, a plan repair method looks like a planning method, or looks like a method that does exactly the opposite, i.e., removing actions from a plan. We propose a general framework for plan repair that shows the relation between these two alternating steps. Any plan repair method has this property. This claim is supported by showing how a number of plan repair systems fit into the presented framework. One of the advantages of a general framework is that it helps to understand existing techniques and improve upon them. As an example of this, we present a novel heuristic for plan repair that can make use of existing planning heuristics. Some initial results are provided that indicate that this heuristic is competitive with existing plan repair methods.