Application of Verification Methods to Specifications of Signalling Equipment

Abstract

Formal methods has been expected to increase the reliability of software, including that of signalling systems. In order to further the use of formal methods in the railway signalling domain, it would be beneficial to show examples of models of various signalling equipment using formal methods. As some examples, the specification of automatic block systems for single lines was modeled using formal specification languages, and the effectiveness of the model was verified by means of theorem proving and satisfiability problem solver. For theorem proving, B-method was used, which is characterized by theorem proving and stepwise refinement. B-method yields a very powerful result as far as safety is concerned, but it requires a high level of effort. On the other hand, satisfiability problem solvers can easily find truth of the proposition composed with many variables, but some restrictions apply in terms of the proposition domain.