Link - Modeling Rule-Based Systems with EMF
Oddly, this may be one of the best definitions of "rule-base system". It's when you do ....
Conventionally, rule-based systems are defined as or are closely associated with expert systems. But the usually ever-reliable Wikipedia mentions them only in the context of expert systems and that only in passing. THe central definition of expert system is:
An expert system, also known as a knowledge based system, is a computer program that contains some of the subject-specific knowledge, and contains the knowledge and analytical skills of one or more human experts.
Several paragraphs later they say: "however some rule-based expert systems are also called wizards". That's all.