Safe diagnosability of discrete-event systems (DESs) is viewed as the first necessary step of fault-tolerant supervision in the literature. For safe diagnosable systems, it is required that not only failures occurring in systems can be detected within a finite delay, but also the detection should be completed before running any unsafe operation. In this paper, we present a novel approach to deal with the safe diagnosis issue for stochastic DESs by constructing a nondeterministic automaton called the safe verifier, and the necessary and sufficient condition for safe diagnosability of stochastic DESs is presented. It is worth noting that the proposed approach has lower complexity than the existing approach based on safe diagnoser as far as the number of states.

离散事件系统（DES）的安全可诊断性在文献中被视为容错监督的第一个必要步骤。对于安全的可诊断系统，要求不仅可以在有限的延迟时间内检测到系统中发生的故障，而且还应该在运行任何不安全的操作之前完成检测。在本文中，我们提出了一种通过构造一个称为安全验证器的非确定性自动机来处理随机 DES 安全诊断问题的新方法，并提出了随机 DES 安全诊断的充分必要条件。值得注意的是，就状态数量而言，所提出的方法比基于安全诊断器的现有方法具有更低的复杂性。