A Repair-Replanning Strategy for HTN-based Therapy Planning Systems ∗

This work presents a strategy to respond to failures during the execution of a treatment plan in the real world. In the first place, the approach (focused on HTN-based therapy planning frameworks) performs an exception analysis episode to identify both the nature and the complexity of the unexpected event. According to these factors, the strategy, firstly, will attempt to carry out a repair of the failed plan by a local adaptation or applying a suitable repair rule in order to make the plan valid to the current context. However, this alternative might not be effective enough for solving errors that require more global and deeper changes. In this case, the strategy will try to construct another suitable sub-plan through a replanning episode for replacing the damaged actions. A mixed-initiative approach is also considered, as last alternative, for repairing the error. Aspects related to plan stability and exploitation of the previous reasoning process are also taken into account.