Expert system with knowledge base having term definition hierarchy

摘要

A definition-based expert system and expert system shell. 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 terms defined at lower levels in the hierarchy or on term-independent values. Expert responses are obtained from the system by evaluating the terms. When a term is evaluated, all of the term-independent values and the values of all of the terms in its definition are obtained. The definitions include operators specifying operations which are to be performed when the defined term is evaluated. The operators include causing other systems operable in the digital computer system in which the expert system is operating to operate. The definitions further include table operators. Base table operators define terms representing tables and columns in the tables and permit loading of the tables. Query table operators define terms representing tables defined from base tables or other query tables. Column operators permit operations involving all of the fields of a column. The expert system is further able to respond to "don't know" values in a fashion which depends on the significance of the "don' t know" value for the definition of the term.