Empowering Domain Experts With Formal Methods for Consistency Verification of Safety Requirements

Consistency verification of safety requirements is crucial for the success of safety-critical systems, particularly railway systems. However, this task often requires significant time spent on interaction and communication between domain experts, who possess in-depth knowledge of safety requirements in a specific domain, and formal experts, who have the necessary skills to apply verification tools and techniques. To enhance time efficiency and productivity, we propose an approach to empower domain experts with formal methods for verifying safety requirements' consistency. This involves transforming natural requirements into formal models and using formal methods for verification. The approach also localizes inconsistent requirements to provide feedback to domain experts. Communication between domain experts and formal experts can be facilitated through the pattern language SafeNL. By adopting this approach, domain experts can utilize formal verification without extensive consultation with formal experts. Two practical case studies with CASCO Signal Ltd. validate its effectiveness, practicality, as well as a significant reduction of time compared to traditional methods (at least 90% reduction). This reduction in time is primarily due to reduced communication needs and more efficient localization. Evaluations show that SafeNL is user-friendly and the approach performs well in modular systems while scalability is somewhat limited.