Reachability Set Generation Using Hybrid Relation Compatible Saturation.

Generating the state space of any finite discrete-state system using symbolic algorithms like saturation requires the use of decision diagrams or compatible structures for encoding its reachability set and transition relations. For systems that can be formally expressed using ordinary Petri Nets (PN), implicit relations, a static alternative to decision diagram-based representation of transition relations, can significantly improve the performance of saturation. However, in practice, some systems require more general models, such as self-modifying Petri nets, which cannot currently utilize implicit relations and thus use decision diagrams that are repeatedly rebuilt to accommodate the changing bounds of the system variables, potentially leading to overhead in saturation algorithm. This work introduces a hybrid representation for transition relations, that combines decision diagrams and implicit relations, to reduce the rebuilding overheads of the saturation algorithm for a general class of models. Experiments on several benchmark models across different tools demonstrate the efficiency of this representation.