An approach towards the verification of hybrid rule/frame-based expert systems using coloured Petri nets

High level Petri nets have recently been used for many AI applications, particularly for modelling traditional rule-based expert systems. The major effect is to facilitate the analysis of the knowledge inference during the reasoning process, and to support the system verification which increasingly becomes an integral part of expert system development. Nevertheless, there is not much attention being put on systems other than the traditional ones. In this paper, we described an approach to model hybrid (rule- and frame-based) expert systems using coloured Petri nets and the concept of controlled state tokens. The analysis of the proposed model is by constructing and examining the readability tree spanned using the knowledge inference. Such methodology has an implication for supporting the verification process in hybrid systems.