Intelligent Systems for Engineers and Scientists, 3rd Edition

2

Rule-Based Systems

2.1 Rules and Facts

A rule-based system is a knowledge-based system (KBS) where the knowledge base is represented in the form of a set, or sets, of rules. Rules are an elegant, expressive, straightforward, and flexible means of expressing knowledge. The simplest type of rule is called a production rule and takes the form

if <condition> then <conclusion>.

An example of a production rule might be

if the tap is open then water flows.

Part of the attraction of using production rules is that they can often be written in a form that closely resembles natural language, as opposed to a computer language. A simple rule like the foregoing one is intelligible to anyone who understands English. Although rules can be considerably more ...