A two-tier approach to rule-based systems verification

Established verification criteria fall into two classes. The first set of verification criteria is focused on the global relationships between the rule clusters (sets of conditions which satisfy common conclusions) such as reachability and dead-end IFs. The second class of verification criteria is concerned with the local properties of a specific rule cluster such as missing rules and inconsistent rules. The significance of this approach is that global criteria are not computationally expensive to test, and it is possible to perform exhaustive testing for local criteria on each rule cluster because of the smaller size. If properly verified, the rule base represents a closed world, so local verification criteria are met for the rule base as a whole if they are met for each rule cluster individually. This approach allows exhaustive global testing and exhaustive local testing for all but the most exotic domains. The result is expert systems worthy of the name.<>