Reduction methods for real-time systems using Delay Time Petri Nets

We present a new net-reduction methodology to facilitate the analysis of real-time systems using Delay Time Petri Nets (DTPNs). Net reduction is one of the most important techniques for reducing the state-explosion problem of Petri nets. However, the application of net reduction to current timed-extensions of Petri nets (such as Merlin's Time PNs) is very limited due to the difficulty faced in the preservation of timing constraints. To overcome this problem, we introduce DTPNs which are inspired by Merlin's (1976) Time PNs, Senac's (1994) Hierarchical Time Stream PNs, and Little's (1991) Timed PNs. We show that DTPNs are much more suitable for net reduction. Then, we present a new set of DTPN reduction rules for the analysis of schedule and deadlock analysis. Our work is distinct from the others since our goal is to analyze real-time systems and the reduction methods we propose preserve both timing properties (schedule) and deadlock. To evaluate our framework, we have implemented an automated analysis tool whose main functions include net reduction and class-graph generation. The experimental results show that our net-reduction methodology leads to a significant contribution to the efficient analysis of real-time systems.