Advancements in Dependability Analysis of Safety-Critical Systems : Addressing Specification Formulation and Verification Challenges

Abstract: Safety-critical systems have garnered increasing attention, particularly regarding their dependability analysis. In modern times, these systems comprise numerous components, making it crucial to verify that lower-level components adhere to their specifications will ensure the overall system’s compliance with its top-level specification. However, two issues arise in this verification process. Firstly, many industrial applications lack lower-level natural-language specifications for their components, relying solely on toplevel specifications. Secondly, many current verification algorithms need to explore the continuous time evolution of the behavioral combinations of these components, and the combination of components to be explored will rise exponentially with the number of components. To address these challenges, this paper presents significant contributions. Firstly, it introduces a novel method that leverages the structures of redundancy systems to create naturallanguage specifications for components derived from a top-level specification. This approach facilitates a more efficient decomposition of the top-level specification, allowing for greater ease in handling component behaviors. Secondly, the proposed method is successfully applied to Scania’s brake system, leading to the decomposition of its top-level specification. To verify this decomposition, an existing verification algorithm is selected, and the results are impressive. The proposed method effectively addresses the issue of exponential growth in component behavior combinations, which was previously mentioned. Specifically, in the case of the Scania brake system, the number of combinations is dramatically reduced from 27 to a mere 13, showcasing the significant improvement achieved with the new method.