Improved Question-Guided Stubborn Set Methods for State Properties

We present two new question-guided stubborn set methods for state properties. The first method makes it possible to determine whether a marking is reachable in which a given state property holds. It generalises the results on stubborn sets for state properties recently suggested by Schmidt in the sense that that stubborn set method can be seen as an implementation of our more general method. We propose also alternative, more powerful implementations that have the potential of leading to better reduction results. This potential is demonstrated on some practical case studies. As an extension of the first method, we present a second method which makes it possible to determine if from all reachable markings it is possible to reach a marking where a given state property holds. The novelty of this method is that it does not rely on ensuring that no transition is ignored in the reduced state space. Again, the benefit is in the potential for better reduction results. Topics: System design and verification using nets, Analysis and synthesis of nets, Computer tools for nets.