ABSTRACT
Expert system shells are designed to allow the rapid design and
implementation of rule-based expert systems, but tend to lack flexibility. The
programming languages offer much greater flexibility and can be used to build
customized tools. Most programming languages are procedural rather than
declarative, although the Prolog language incorporates both programming
styles. The KBS toolkits aim to provide the best of all worlds. They typically
offer a mixture of facilities so the programmer has free access to the
underlying language and to tools such as rule-based and object-oriented
programming. The provision of these tools can save considerable programming
effort, while the ability to access the underlying language gives the freedom to
build extra facilities.
