Catálogo de publicaciones - libros

We present an approach to modelling Abadi-Cardelli-style object calculi as Unifying Theories of Programming (UTP) designs. Here we provide a core object calculus with an operational semantics, and a corresponding UTP model with a denotational semantics. For clarity, the UTP model is defined in terms of an operand stack, which is used to store the results of subprograms. Models of a less operational nature are briefly discussed. The consistency of the UTP model is demonstrated by a structural induction proof over the operations of the core object calculus. Overall, our UTP model is intended to provide facilities for encoding both object-based and class-based languages.

An increasing interest in “Systems of Systems”, that is, Systems comprising a varying number of interconnected sub-systems, raises the need for automated verification techniques for dynamic process creation and a changing communication topology. In previous work, we developed a verification approach that is based on finitary abstraction via Data-Type Reduction. To be effective in practice, the abstraction has to be complemented by non-trivial assumptions about valid communication behaviour, so-called non-interference lemmata.

In this paper, we mechanise the generation and validation of these kind of non-interference properties by integrating ideas from communication observation and counter abstraction. We thereby provide a fully automatic procedure to substantially increase the precision of the abstraction.

We explain our approach in terms of a modelling language for dynamic communication systems, and use a running example of a car platooning system to demonstrate the effectiveness of our extensions.

Development of computerized embedded control systems is difficult because it brings together systems theory, electrical engineering and computer science. The engineering and analysis approaches advocated by these disciplines are fundamentally different which complicates reasoning about e.g. performance at the system level. We propose a light-weight approach that alleviates this problem to some extent. An existing formal semantic framework for discrete event models is extended to allow for consistent co-simulation of continuous time models from within this framework. It enables integrated models that can be checked by simulation in addition to the verification and validation techniques already offered by each discipline individually. The level of confidence in the design can now be raised in the very early stages of the system design life-cycle instead of postponing system-level design issues until the integration and test phase is reached. We demonstrate the extended semantic framework by co-simulation of VDM++ and bond-graph models on a case study, the level control of a water tank.