Chapter 8: Introduction to Rules-Based Systems

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In this chapter, we'll look at one of the original symbolic AI systems, the knowledge-based system. These systems are also called expert systems (or production systems), where knowledge is encoded in rules. Knowledge (or facts) is stored in a working memory, and the rules are applied to the knowledge to create more knowledge. This process continues until some goal state is reached. We'll investigate a simple rules-based system in this chapter along with an application in the domain of fault tolerance.

Introduction

While a number of different types of rules-based systems exist, we'll focus on a combination of two particular kinds called the deduction system and the reaction system. A deduction system consists of rules representing antecedents and consequents. An antecedent is a condition (an "if" statement, if you will) while the consequent represents the resulting action (the "then" portion). By deduction, the rules insert new facts into the working memory that were " deduced " (reasoned by deduction ) from the existing working memory by a given rule. A reaction system includes "actions" that are performed as part of the consequent, such as issuing a command in an embedded system to alter the environment.