Issues in the development of expert systems

Expert systems are computer programs which use rules and facts as data. This data is stored external to the program and is called a knowledge base. The expert program uses an inferential engine to examine the relationships between the rules and facts and draw conclusions. Hayes-Roth (1984> gives a full definition of expert system technology. While these systems can be interfaced with other programs and datay often they are stand alone programs. The expert system is the overall framework which is interfaced to peripheral needs. Even though there are functional ties to external needs, this design necessarily limits the use of expert systems. It narrows the potential of the expert system technology to those applications which fit the shell. Some criticism about this approach has been made. For example, Expert system shells often have limited access to existing data bases. Is seems that expert systems are used when there is an identifiable application which requires an expert system shell. If the task fits the expert system shell, then the system is developed. Although there are many important applications which can cost justify large system development with the shell~ there may be many small applications which could use expert system technology. These needs may be limited in scope. The required knowledge base may consist of only a few rules and facts. Cost ~ustification for the shell may not exist. Is ~bere a methodology available to fill this need? In addition, a traditional application may have a requirement for rule based inferential processing. It would seem unreasonable to center the project around an expert shell if only a small portion of the proposal required an inferential engine. Could the project be handled with the traditional approach and integrate the limited rule based requirements into the entire system? Is it possible to use inferential processing without an expensive stand alone shell? Is it possible to apply this technology to the application rather than orient the application around the expert Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission.