Some solutions to the ignoring problem

The ignoring problem refers to the fact that some actions may be infinitely postponed by a state space search algorithm that makes use of partial order reduction (POR). The prevention of this phenomenon is mandatory if one wants to verify more elaborate properties than the deadlock freeness, e.g., safety or liveness properties. We present in this work some solutions to this problem. In order to assess the quality of our propositions, we included them in our model checker Helena. We report the result of some experiments which show that our algorithms yield better reductions than state of the art algorithms like those implemented in the Spin tool.