Expert-Systems

Abstract

Expert-system technology, now widely used as a component of larger software systems, is characterized by the separation of heuristic knowledge (i.e., a set of if-then rules) in a program from the rest of the system. An expert-system shell provides a higher level language for expressing problem-solving knowledge in the form of if-then rules. Expert-system construction is facilitated by the use of an existing shell tool. Both public domain and commercial expert-system building shells are available in many programming languages (e.g., LISP, C, Fortran, and Ada). This chapter begins with a definition of terms used to discuss expert-systems, then presents example shells suitable for educational use; they can be extended in your application programs to build a customized high-level programming language environment for adding modular knowledge bases to the systems that you build. Then a backward-chaining expert-system shell is developed which starts with a goal and searches backwards until an initial state is found. This chapter also discusses features to look for in commercial expert-system shells, and recommends two public domain tools now widely used for building expert-systems, then ends with suggested expert-system projects.