Expert system and expert system shell

摘要

The expert system shell creates a knowledge base consisting of terms and their definitions, the definitions making up a hierarchy of definitions in which each definition depends only on definitions at lower levels in the hierarchy or on values obtd. from sources external to the knowledge base. The expert system shell creates the knowledge base by asking the expert to define a given term and then asking him to define all undefined terms which appear in the definition of the given term. The expert systems employ an inferencing engine which determines the value of a given term by evaluating its definition. In the course of the evaluation, the definitions of terms required to define the given term are evaluated and external values required for the evaluation and external values required for the evaluation of the definitions are obtd. Users of the expert system may inquire of the system why it is seeking a given external value and how it obtd. the results it did.