Expert System Shells

Expert system shells provide methods of building expert systems without extensive knowledge of programming through mechanisms that

 (1) input the decisions, questions and rules that are followed 

(2) construct a knowledge database that can be manipulated by subsequent parts of the system 

(3) verifies possible violations of surface validity and 

(4) operates the "inference engine" that operates on the rules, poses the questions to the users, and determines whether a particular decision is valid. 

 

 

Most expert systems also allow the user to halt the processing at any time to query the system why a question was asked, or how a decision was reached

 Most expert system shells can now run easily on most current micro-computers and are able to handle the manipulation of a relatively large number of rules and associated questions.

 Expert system shells a re expert system development tools consisting essentially of the expert system without the knowledge base, embodying the inference engine, working memory, and the user interface (Sener, 1991). An example of the inference engine part of an expert system that deduces new conclusions from known facts is illustrated below

IF liquid limit=known
AND plastic limit=known
AND plastic limit>liquid limit
THEN soil=non plastic

Expert systems give advice or solve problems by drawing upon this knowledge stored in the IF/THEN rules.