A Tool for Deadlock Analysis of Parameterized-chain Networks

This paper studies algorithmic aspects of deadlock analysis for parameterized networks of discrete-event systems. A parameterized network consists of interacting finite-state subsystems, including finite but arbitrarily large numbers of subsystems within each of a finite number of isomorphism classes. While deadlock analysis of such systems is generally undecidable, decidable subproblems have recently been identified. The decision procedure of Zibaeenejad and Thistle (2017) rests on the construction of a finite dependency graph for the network, and the computation of its full, consistent subgraphs. We present a software tool that takes the template of a Parameterized Chain Network (PCN) and outputs the set of all full, consistent subgraphs of the dependency graph. These subgraphs represent infinite set of deadlocked states of the PCN for all parameter values. As a case study, we investigate deadlock in a complex train network that extends beyond the current theoretical framework. The results suggest ways in which the framework could be extended.