An explanation shell for expert systems

Abstract
We describe a shell for expert systems written in Prolog. The shell provides a consultation environment and a range of explanation capabilities. The design of the shell is modular, making it very easy to extend the shell with extra features required by a particular expert system. The novelty of the shell is twofold. Firstly, it has a uniform design consisting of an integrated collection of meta‐interpreters. Secondly, there is a new approach for explaining ‘why not,’ when a query to the system fails.