Reference: Ash, D. & Hayes-Roth, B. Action-Based Fault Hierarchies for Real-Time Response. 1992.
Abstract: For an agent to act intelligently in real-time, it often must be willing to act despite the lack of sufficient resources to make a complete diagnosis. In particular, it is often necessary to trade off specificity for time- substituting a more general but less desirable action when time does not permit determining the optimal action. In this paper, we introduce a structure, called the action-based fault hierarchy, which provides an agent with an action to perform at all times, ranging from general actions at the top of the hierarchy to specific actions at the leaf nodes. We also present some formal results on the optimal structure for action-based hierarchies under certain conditions. We conclude with a brief description of an implementation of action-based hierarchies, ReAct, in the Guardian intensive- care patient monitoring system.