J. Paul Gibson

J Paul Gibson, Dominique Méry

The increasing development of cyber-physical systems (CPSs) requires modellers to represent and reason about physical values. This paper addresses two major, inter-related, aspects that arise when modelling physical measures. Firstly, there is often a heterogeneity of representation; for example: speed can be represented in many different units (mph, kph, mps, etc. . . ). Secondly, there is incoherence in composition; for example: adding a speed to a temperature would provide a meaningless result in the physical world, even though such a purely mathematical operation is meaningful in the abstract. These aspects are problematic when implicit semantics - concerned with measurements - in CPSs are not explicit (enough) in the requirements, design and implementation models. We present an engineering approach for explicitly modelling measurements during all phases of formal system development. We illustrate this by moving from Event-B models to Java implementations, via object oriented design.

Paul Gibson

Students often learn formal methods as part of a software engineering degree programme, without applying these formal methods outside of the specific module(s) dedicated to this subject. In particular, software engineering students often have to build a significant application/program/system in a substantial project at the end of their programme (in order to demonstrate the application of the things they have learned during the previous taught modules). Our experience shows that the majority of students do not use formal methods in this project work. We report on feedback from the minority of students who did choose to use formal methods in their projects, and give examples of where this was a help and where it was a hindrance.