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Artificial Intelligence and Soft Computing: Behavioral ... - Arteimi.info

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The chapter will cover various issues relating to validation,<br />

verification <strong>and</strong> maintenance of knowledge-based systems.<br />

21.2 Validation of Expert Systems<br />

Validation of an expert system involves comparing the performance of the<br />

system with an ideal system (or the expert) <strong>and</strong> then updating the knowledge<br />

base <strong>and</strong> the inferential procedures, depending on the deviation of the expert<br />

system performance from that of the ideal system. Validating a system, thus,<br />

not only means checking its performance with the expert, but it also includes<br />

the procedures to adjust the systems’ parameters. A schematic view for<br />

validation of an expert system is presented in fig. 21.3.<br />

Problem i<br />

Expert System<br />

KB<br />

IE<br />

Human Expert<br />

DB<br />

Inference<br />

& Explanation Error<br />

Inference & Explanation<br />

Fig. 21.3: Validating an expert system.<br />

Procedure to adjust<br />

KB & IE<br />

The expert system in fig. 21.3 comprises of three modules: the database<br />

(DB), the knowledge base (KB) <strong>and</strong> the inference engine (IE). The IE<br />

interprets the DB with the KB <strong>and</strong> thus derives inferences <strong>and</strong> presents<br />

explanation to the performance evaluator (PE). A human expert is also given<br />

the same problem, to infer its conclusion <strong>and</strong> present a suitable explanation<br />

for its conclusion. If the conclusions generated by the expert system deviates<br />

from the inferences by the expert, the explanation traced by the system <strong>and</strong><br />

the expert may be compared to determine the disparity in rule firing. Let the<br />

state-space graph corresponding to the system <strong>and</strong> the expert be like those in<br />

fig. 21.4.<br />

PE

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