Which Contingent Events to Observe for the Dynamic Controllability of a Plan

Planning and acting in a dynamic environment require distinguishing controllable and contingent events and checking the dynamic controllability of plans. Known procedures for testing the dynamic controllability assume that all contingent events are observable. Often this assumption does not hold. We consider here the general case of networks with invisible as well as observable contingent points. We propose a first procedure for testing their dynamic controllability. Further, we define an algorithm for choosing among the observable contingent points which to observe with additional sensing actions, such as to make a plan dynamically controllable. We show how these procedures can be incrementally integrated into a constraint-based temporal planner.