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 suggest a new method which is based on
the widely used RETE match algorithm. We show an approach to reduce the response time of
rule-based expert systems with reducing matching time.
There are two approaches in the method we propose: The first makes an index structure of tokens
to reduce the alpha-node-level join candidates. The second chooses the highest time tag for
certain beta nodes to reduce the size of beta-memory and to keep the strategy of the RETE
network. These approaches reduce the amount of combinatorial match that is problematical in
real-time production system application. For this purpose, a simple compiler which is
implemented in C and response time is measured.