Shortening matching time in OPS5 production systems

A rule-based system must satisfy stringent timing constraints when applied to a real-time environment. As the scale of rule-based expert systems increases, the efficiency of systems becomes a pressing concern. The most critical performance factor in the implementation of a production system is the condition-testing algorithm. We propose a new method based on the widely used RETE match algorithm. We show an approach designed to reduce the response time of rule-based expert systems by reducing the matching time. There are two steps in the method we propose: The first makes an index structure of the tokens to reduce the α-node-level join candidates. The second chooses the highest time tag for certain β-nodes to reduce the amount of combinatorial match that is problematical in a real-time production system application. For this purpose, a simple compiler is implemented in C and the response time of test programs is measured.