Using the Event-B Formal Method and the Rodin Framework for Verification the Knowledge Base of an Rule-Based Expert System

Abstract

Verification and validation of a knowledge base of an expert systems are distinct activities that allow to increase the quality and reliability of these systems. While validation ensures the compliance of a developed knowledge base with the initial requirements, the verification ensures that the knowledge base is logically consistent. Our work is focused on the verification activity, which is a difficult task that mainly consists in determination of potential structural errors of the knowledge base. More exactly, we aimed to study the consistency of knowledge bases of rule-based expert systems that use the forward chaining inference, a very important aspect in the verification activity, among others, such as completeness and correctness. We use Event-B as a modelling language because it has a mathematical background that allows to model a dynamic system by specifying its static and dynamic properties. In addition we use the Rodin platform, a support tool for Event-B, which allows to verify the correctness of the specified systems and its properties. For a better understanding of our method, an example written in the CLIPS language is presented in the paper.