Procedural control in production systems

摘要

This paper proposes a general production system architecture that allows procedural control knowledge to be directly represented and used. This architecture, called a controlled production system, is based on a separately specified control structure that effects control over production invocation and interaction independently of the search strategy.It is shown that a controlled production system provides a basis for describing and implementing control constructs which, unlike most existing schemes, is formally adequate and retains all the properties desired of a knowledge based system—modularity, flexibility, extensibility and explanatory capacity. We also show that this architecture provides for a uniform programming methodology—the procedural languages and the declarative languages turn out to be special cases of a controlled production system.Schemes for improving system efficiency and resolving nondeterminism are also examined. It is shown that the separate representation of control provides a basis for a theory of efficiency transformations on production systems, and allows for more effective means of directing search.