In this project, several extensions to the GNU Prolog tool have been implemented. The underlying reason for these extensions is to improve the practical applicability of the tool for Axini’s purposes. This is because Axini makes use of GNU Prolog’s finite domain constraint solver in its Model-based Testing tool, called TestManager. The intended extensions for GNU Prolog constraint solver are:

• to include negative values in the finite domain variables.
• to improve the usability by preventing overflows from occurring.
• to reduce/remove the limitations of the sparse domain representation.

This report discusses the methodology and techniques used for implementing the extensions. A focus is laid on correctness and performance. The report analyzes each extension in detail, after which possible alternatives are discussed. The chosen approaches are motivated and the implementation is discussed with the use of examples.

The results show that each extension is successfully implemented. The performance evaluation of this initial implementation shows encouraging results, with a limited slowdown factor compared to the original constraint solver. The developers of GNU Prolog are pleased with the results and aim to incorporate the extensions in a future release of GNU Prolog.