Improved Approaches for Verifying I-Detectability of Discrete-Event Systems

In this paper, we investigate the initial-state detection problem in the context of partially-observed discrete-event systems. Specifically, we study the verification of two properties called weak I-detectability and strong I-detectability. Weak detectability captures whether or not the initial-state of the system can be detected via some path, while strong detectability captures whether or not the initial-state of the system can always be detected within a finite delay. In this paper, we provide new verification algorithms for checking these two properties. The idea is to use the reversed dynamic of the system to efficiently estimate the initial-state information. We show that our new results improve the complexity of existing verification algorithms for both properties. We illustrate our results by simple examples.