An Approach to Nonmonotonic Inference Mechanism in Production System KORE/IE

In this paper, we propose a method for constructing a mechanism for nonmonotonic inference in KORE/IE which is a Prolog based forward-chaining production system. In the implementation, we utilize the form of default reasoning proposed by Reiter, and introduce the framework of TMS(Truth Maintenance System) for resolving contradictions. Relational information such as data dependencies is independently managed by KORE/EDEN, a network-based knowledge management system, for improving dependency-directed backtracking in TMS. Resolving contradictions is achieved by undoing the inference. The mechanism for resolving a contradiction can be realized by extending the inference steppers in KORE/IE along the framework of TMS. As an example of the mechanism, we show a maintenance mechanism for pairwise comparisons. Consistency of the comparisons is effectively maintained by using the mechanism.