The user supplies facts or other information to the expert system and receives expert advice or expertise in response. Intenally, the expert system consists of two main components. The knowledge-base contains the knowledge with which the inference engine draws conclisions. These conclusions are the expert system's resposes to the user's queries for expertise.
Giarratano, J. dan
Riley, G., 2005, Expert System Principles
and Programming, PWS Publishing Company, Boston.