Maintainability techniques in developing large expert systems

The production of understandable and maintainable expert systems using the current generation of multiparadigm development tools is addressed. This issue is discussed in the context of COMPASS, a large and complex expert system that helps maintain an electronic telephone exchange. As part of the work on COMPASS, several techniques to aid maintainability were developed and successfully implemented. Some of the techniques were new, others were derived from traditional software engineering but modified to fit the rapid prototyping approach of expert system building. An overview of the COMPASS project is presented, software problem areas are identified, solutions adopted in the final system are described and how these solutions can be generalized is discussed.<>