g-HOL: A Graphical User Interface for the HOL Proof Assistant

Given the high expressiveness of higher-order logic, their proof assistants are being widely advocated for formally verifying cyber-physical systems these days. However, the usage of higher-order-logic proof assistants is mostly restricted to academia. One of the main reasons for the hesitancy of their usage in industrial setting is the associated long learning curve. We believe that one of the foremost factors behind this slow learning process is the user-unfriendly text-based interfaces of the proof assistants. To facilitate the first experience of users with a proof assistant, this paper presents a user-friendly graphical user interface (GUI) g-HOL for the higher-order-logic (HOL) proof assistant. g-HOL is developed in Java swing and is supported by the Windows, Linux and MAC operating systems. It tends to minimize syntax errors and the need to memorize and type commands and facilitates the searching process, which is frequently required in interactive formal reasoning. The paper describes the architecture and main features of g-HOL using an illustrative example.