ClawZ is a prototype tool whose objective is to link the Simulink control engineering tool, from MathWorks, with the dialect of Z. It provides a bridge between the use of Simulink to define control law diagrams and a tool to formally prove compliance between Ada and Z. The tool has been used as part of the formal proof of a Non-linear Dynamic Inversion flight control system comprising 37 pages ...

The engineering processes for safety-critical systems, for instance in the health care or transportation domains, are regulated by law. For software in the railroad industry in Europe the certification procedures have to obey the norm EN50128. This paper presents the method that was introduced and employed for the development and the successful certification of the software for the vehicle cont...

Prior literature has produced two theoretically opposing perspectives on the relationship between clan control, a type of cultural control, and formal control. Some researchers view formal control as the antithesis of clan control, while others suggest that formal control facilitates clan control. In this research-in-progress paper, we argue that formal control and clan control can be both subs...

1. Introduction Railway signalling is a safety critical system. Special hardware for safety has been used in signalling systems. Recently computer has been widely introduced and software is much more responsible for safety. As far as hardware aspect of safety computer is concerned, there has been a lot of progress. Special devices for safety have been developed and used widely. But the safety t...

Computing facilities networked together but controlled by different administrations pose a problem of access control. Who decides who can use what? We specify a formal model for an access control system which allows users and services from different administrations to communicate with each other, while still allowing the administrators to retain control of their own parts of the network. The mo...

Transportation control systems are safety critical systems. While a couple of years ago control systems mainly used to be built up from (electro-) mechanical devices, nowadays more and more functionality is software controlled. To sustain the high level safety standards for these embedded systems, we propose to use fault tree analysis integrated with formal methods for analyzing system safety. ...