Developing An Interface For HOL

The HOL system is being increasingly used for a variety of theorem-proving and verification tasks, and by specialists an a variety of domains. A hindrance in making it more accessible is the austere, prompt-based interface to the logic. Many users find the methods for conducting proofs too restrictive. This paper describes a set of tools designed at Cambridge for improving interaction with the HOL proof environment. These tools, though useful at all levels, aim primarily at supporting the experienced user: they provide the same degree of transparency which allows close control of the proof environment-an aspect exploited by many users-while providing an easier intera.ction.