For courses in Expert Systems, Knowledge-Based Systems, Artificial Intelligence or Decision Support Systems, this book embodies the fact that expert systems now extend beyond the field of computer science into such areas as engineering and business. It offers a comprehensive understanding of expert systems and shows their application to real world problems. The material is presented in such a way that the student needs no previous experience in computers or computer programming. The book addresses all of the topics necessary to understand, build, validate, and implement expert systems - with many examples, exercises, and problems. A working version of EXSYS - a microcomputer-based expert systems software program - is packaged with the text.