Plan execution in dynamic and unanticipated environments

The construction of planning and execution systems for complex real-time operational systems should be based on an understanding of what happens at the time of plan execution, because much of the information to constrain reasoning and decisions is not available prior to execution. The author discusses the results of research on the execution of procedures of a knowledge-rich domain (operation of a nuclear power plant) in a dynamic environment, and concludes that planning+execution is a viable model where planning is better viewed as a process for producing a `road map´ and that the research needs to focus more on the role of the executor as an intelligent navigator. It is also shown that an understanding of domain-specific execution behavior can lead to strategies for dealing with the incompleteness problem. The author briefly describes salient features of the DPS (dynamic procedure selection and synthesis) approach and shows how some of the aspects of incompleteness can be addressed by exploiting both the knowledge richness of a domain and architectural features of plan execution behavior