Knowledge Engineering

Additional layers of rules (continued):
	The information in a knowledge base is sometimes clarified by forming a new rule to capture a common theme found in several rules. Consider the following two rule fragments: If the headlights light and the starter cranks normally and you smell gasoline then... If the headlights light and the starter cranks normally and you do not smell gasoline then... A common theme that could be extracted from these two rules and placed in a separate rule is the evidence that the problem is not electrical: If the headlights light and the starter cranks normally then the problem is not electrical Then the original rules would be written as follows: If the problem is not electrical and you smell gasoline then... If the problem is not electrical and you do not smell gasoline then... Optional revisions of this type may clarify the intent of rules to make the explanation of the expert system's advice more understandable.
Analytical tools that support formulating and documenting the knowledge base include...