Generating Understandable and Reusable Safety Assurance Cases using Workflow⁺

The production of rigorous safety assurance cases is notoriously difficult and expensive. One of the primary reasons for this is the ever increasing complexity of modern-day systems, their artefacts (such as design models) and associated safety arguments. In previous work we proposed an approach to producing and structuring assurance cases using Workflow<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup>. Here we expand upon that work by including concepts from assurance case templates (ACTs) into arguments in WF<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup>, allowing them to be significantly more compact and understandable by keeping details about the system in evidence and out of arguments. We argue that this allows for more understandable and reusable arguments, and also supports more systematic generation of assurance arguments.