Statecharts: A visual formalism for complex systems
Science of Computer Programming
Safeware: system safety and computers
Safeware: system safety and computers
What is in a Step: On the Semantics of Statecharts
TACS '91 Proceedings of the International Conference on Theoretical Aspects of Computer Software
Safecharts for Specifying and Designing Safety Critical Systems
SRDS '99 Proceedings of the 18th IEEE Symposium on Reliable Distributed Systems
A Model Checker for Statecharts
A Model Checker for Statecharts
Modeling and verification of safety-critical systems using safecharts
FORTE'05 Proceedings of the 25th IFIP WG 6.1 international conference on Formal Techniques for Networked and Distributed Systems
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Safecharts [2] are a variant of Statecharts developed exclusively for use in safety critical systems design. Its distinctive features include a safety oriented characterisation of transitions, restriction of default states to safe states, resolution of any nondeterminism in favour of safe transitions and representation of failures of items of equipment. These are achieved through ordering of system states according to risk levels. As a matter of principle, Safecharts permit transitions only between states with known risk levels. As a result, the effectiveness of Safecharts depends largely on the extent of coverage of the state space by the risk ordering relation. Risk band is a new concept used for default interpretation of risk levels of such states, both to alert the designer to the implications of any inadequacies in hazard analysis and to reduce nondeterministic behaviour. An example drawn from nuclear industry demonstrates the application of Safecharts.