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464 Part Three Key System Applications for the Digital Age

FIGURE 11.5 RULES IN AN EXPERT SYSTEM

An expert system contains a number of rules to be followed. The rules are interconnected; the number of outcomes is known in
advance and is limited; there are multiple paths to the same outcome; and the system can consider multiple rules at a single time.
The rules illustrated are for simple credit-granting expert systems.

FIGURE 11.6 INFERENCE ENGINES IN EXPERT SYSTEMS

An inference engine works by searching through the rules and “firing” those rules that are triggered by facts gathered and entered
by the user. Basically, a collection of rules is similar to a series of nested IF statements in a traditional software program; however,
the magnitude of the statements and degree of nesting are much greater in an expert system.

MIS_13_Ch_11 Global.indd 464 1/17/2013 2:30:04 PM