Validating ETCS Data with the B Mathematical Language: An Industrial Pipeline and a Blueprint for LLM Integration

Source abstract

Abstract Can large language models participate in the production and validation of ERTMS/ETCS data without undermining the certification arguments required by CENELEC EN 50128/50716? ERTMS/ETCS is a distributed safety-critical system (trackside, onboard, radio-block centre) whose behaviour is parameterised by large volumes of data drawn from the UNISIG Subsets; errors in that data propagate through the distributed architecture. This paper reports the current status of an ongoing industrial research effort at CLEARSY, ValidAItion , that bridges the ERTMS Operational Simulator to the CLEARSY Data Solver and applies rules expressed in the B mathematical language to that trackside data. During construction, a large language model (Claude) has authored the rule corpus and the parsers through a Model Context Protocol server; every proposal is adjudicated by the downstream toolchain and by systematic human review, and the toolchain has already rejected a syntactically valid but semantically illegal generated scenario. The contribution is architectural and industrial, not algorithmic: the work combines frameworks already in use at CLEARSY (CLEARSY Data Solver, ERTMS Operational Simulator) with a conversational authoring loop, rather than proposing a new formal method. It is a progress report: rule coverage is growing, the human-review campaign is underway, and the quantitative results will be published separately. The paper argues, on the evidence gathered so far, that formal rules in the mathematical language of B must remain the source of truth, while the language model serves as the fenced assistant in a distributed safety-critical railway system: AI proposes, the formal oracle disposes, the human confirms.