Partial Order Reduction in Presence of Rendez-vous Communications with Priority Choice and Weak Fairness

If synchronizing (rendez-vous) communications are used in Promela models, the priority choice feature (unless construct) and the weak fairness algorithm are not compatible with the partial order reduction algorithm used in Spin’s verifier. After identifying the wrong partial order reduction pattern that causes both incompatibilities, we give solutions to these two problems. To this end we propose corrections in the identification of the safe statements for partial order reduction and, as an alternative, we discuss corrections of the partial order reduction algorithm.