Date Added: Jan 2011
In the designing and implementing of any expert system, there are many problems should be considered and study carefully. In reality, human experts have common sense, deduction and analogical reasoning facilities. These three facilities are not included in one knowledge representation scheme, since the logical deduction in the rule base, analogical reasoning in the case base, and the common sense can be applied using blackboard. Therefore, many expert systems have been studied and concentrating in the knowledge engineering methodologies and through the literature survey it is found that most of them are use either mixing rule base with fuzzy logic or mixing rule base with case base.