Reliability is a fundamental property for critical systems. A thorough evaluation of the reliability is required by the certification procedures in various application domains, and it is important to support the exploration of the space of the design solutions. In this paper we propose a new, fully automated approach to the reliability analysis of complex redundant architectures. Given an abstract description of the architecture, the approach automatically extracts a fault tree and a symbolic reliability function, i.e. a program mapping the probability of fault of the basic components to the probability that the overall architecture deviates from the expected behavior. The proposed approach heavily relies on formal methods, by representing the architecture blocks as Uninterpreted Functions, and using the so-called miter construction to model the deviation from the nominal behavior. The extraction of all the deviation conditions is reduced to an AllSMT problem, and we extract the reliability function by traversing the Binary Decision Diagram corresponding to the quantified formula. Predicate abstraction is used to partition and speed up the computation. The approach has been implemented leveraging formal tools for model checking and safety assessment. A thorough experimental evaluation demonstrates its generality and effectiveness of the proposed techniques.

中文翻译：

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冗余架构的形式可靠性分析

可靠性是关键系统的基本属性。各种应用领域的认证程序都要求对可靠性进行全面评估，支持探索设计解决方案的空间非常重要。在本文中，我们提出了一种新的、全自动的方法来分析复杂冗余架构的可靠性。给定架构的抽象描述，该方法自动提取故障树和符号可靠性函数，即程序将基本组件的故障概率映射到整体架构偏离预期行为的概率。所提出的方法在很大程度上依赖于形式化方法，将架构块表示为未解释的函数，并使用所谓的斜接构造以模拟与标称行为的偏差。将所有偏差条件的提取简化为一个AllSMT问题，我们通过遍历量化公式对应的二元决策图来提取可靠性函数。谓词抽象用于划分和加速计算。该方法已利用用于模型检查和安全评估的正式工具实施。彻底的实验评估证明了所提出技术的普遍性和有效性。