Six-Assurance Case Patterns by Strengthening/Weakening Argument

Goal structuring notation (GSN) is widely used in safety cases and other methods for assuring reliability. Demonstrating the fulfillment of a claim in the GSN requires that its achievement be interpreted logically and structurally by the reader. This study proposes a typical pattern of interpreting these structural interpretations. Furthermore, the proposed patterns were verified for their application to actual GSN samples, and the applicability of these patterns was validated. In addition, these patterns were compared with the existing use of the so-called multi-legged arguments, and the differences between them were shown. Moreover, some of the proposed patterns show that there is a difference in the degree of certainty in the achievement of the converted claim, which indicates achievement of the claim from which it is derived.

A Composite Safety Assurance Method for Developing System Architecture Using Model Checking

Assurance case helps analyze the system dependability, but the relationships between system elements and assurance case are generally not clearly defined. In order to make system assurance more intuitive and reliable, this paper proposes an approach that clearly defines the relationships between safety issues and system elements and integrates them using ArchiMate. Also, the proposed method applies model checking to system safety assurance, and the checking results are regarded as evidence of assurance cases. This method consists of four steps: interaction visualization, processes model checking, assurance case creation, and composite safety assurance. The significance of this work is that it provides a formalized procedure for safety-critical system assurance, which could increase the confidence in system safety. It would be expected to make the safety of a system easier to explain to third parties and make the system assurance more intuitive and effective. Also, a case study on an automatic driving system is carried out to confirm the effectiveness of this approach.