This paper focuses on the approaches used in safety cases for software based systems. We outline the history of approaches for assuring the safety of software-based systems, the current uptake of safety and assurance cases and the current practice on structured safety cases. Directions for further development are discussed. 1 History of Computer System Safety and Related Standards The nuclear i...

Very high reliability figures cannot be formally justified for a piece of software. Failure probabilities lower than 1E-4 are rarely claimed or justified even in a highly diversified software system, and there is not an accepted approach for the use of quantitative evaluation for software reliability between the different countries. The situation is even more difficult concerning figures for so...

Safety-critical software-dependent systems such as those found in the avionics, automotive, maritime, and energy domains often need to be certified based on one or more safety standards. An important prerequisite for demonstrating compliance to software safety standards such as IEC 61508 is the collection of safety evidence. Without an upfront agreement between the system supplier and the certi...

In this article a new method for a consistent object-based software construction will be suggested, that allows a straightforward modeling of embedded applications. To this aim new diagram types, the so-called state-based collaboration diagrams, collaboration diagrams in layer models and client-server object diagrams will be introduced. The client-server object diagram is completely UML-conform...

This paper presents a formalisation of a subset of the C programming language, and a corresponding verification calculus, in the theorem prover Isabelle. There are of course many and varied approaches to the verification of safety-critical programs. The characteristics of our approach stem from the application domain: the certification of control software for autonomous mobile robots [3]. This ...

Configuration management is essential for system safety. It helps to ensure that requirements and constraints, which are identified in previous stages of development, are preserved through subsequent modifications. It has, therefore, been recognized as a core component for standards ranging from IEC 61508 through to ISO 9000. Unfortunately, the pressures on development teams to respond to chang...

Der Vortrag stellt im ersten Teil zunächst die wichtigsten Grundprinzipien der organisationsspezifischen Anpassung des V-Modell XT vor. Im zweiten Teil wird darauf aufbauend die Erweiterung des organisationsspezifisch angepassten V-Modell XT um die in den Sicherheitsnormen IEC 61508 und ISO 26262 beschriebenen Anforderungen zur Funktionalen Sicherheit beschrieben. Darauf folgt die operative Ums...

Process-based certification standards such as IEC 61508 and DO178B are often criticised for being highly prescriptive and impeding the adoption of new and novel methods and techniques. Rather than arguing safety based on compliance with a prescribed and fixed process, product-based certification standards require the submission of a well structured and reasoned safety case. Ideally, the safety ...