Techniques for modelling and verifying railway interlockings

We describe a novel framework for modelling railway interlockings which has been developed in conjunction with railway engineers. The modelling language used is CSP(Formula presented.)B. Beyond the modelling we present a variety of abstraction techniques which make the analysis of medium- to large-scale networks feasible. The paper notably introduces a covering technique that allows railway scheme plans to be decomposed into a set of smaller scheme plans. The finitisation and topological abstraction techniques are extended from previous work and are given formal foundations. All three techniques are applicable to other modelling frameworks besides CSP(Formula presented.)B. Being able to apply abstractions and simplifications on the domain model before performing model checking is the key strength of our approach. We demonstrate the use of the framework on a real-life, medium-size scheme plan

On the Multi-Language Construction

Modern software is no more developed in a single programming language. Instead, programmers tend to exploit cross-language interoperability mechanisms to combine code stemming from different languages, and thus yielding fully-fledged multi-language programs. Whilst this approach enables developers to benefit from the strengths of each single-language, on the other hand it complicates the semantics of such programs. Indeed, the resulting multi-language does not meet any of the semantics of the combined languages. In this paper, we broaden the boundary functions-based approach a la Matthews and Findler to propose an algebraic framework that provides a constructive mathematical notion of multi-language able to determine its semantics. The aim of this work is to overcome the lack of a formal method (resp., model) to design (resp., represent) a multi-language, regardless of the inherent nature of the underlying languages. We show that our construction ensures the uniqueness of the semantic function (i.e., the multi-language semantics induced by the combined languages) by proving the initiality of the term model (i.e., the abstract syntax of the multi-language) in its category