SRI International Computer Science Laboratory

Assurance 2.0

Robin Bloomfield and John Rushby

Assurance cases augment earlier approaches to assurance such as standards and guidelines by allowing more choice in selection of techniques for ensuring and justifying safety and other critical properties.

Building on this, Assurance 2.0 is an approach to the development and presentation of assurance cases that is intended to make their construction and assessment more straightforward, yet also more rigorous. In fact, it is rigor that enables straightforwardness because it reduces the "bewilderment of choice" and makes assurance cases more systematic and predictable. Assurance 2.0 employs several ideas that are not in themselves new, but integrates them in a way that we believe is coherent and effective.

Our papers on Assurance 2.0 are listed below in reverse chronological order. We suggest starting with either the "Manifesto" paper (broad but light on details) or the one from Cliff Jones' Festschrift (more technical but also more narrowly focused). Look at the 2-page "Nutshell" when you need a really high-level overview or memory aid.

Assurance 2.0 in a Nutshell (PDF) by Robin Bloomfield and John Rushby. CSL Technical Note October 2024.
Confidence in Assurance 2.0 Cases by Robin Bloomfield and John Rushby. Also available as arXiv 2409.10665.
Expanded version of a paper from The Practice of Formal Methods: Essays in Honour of Cliff Jones, Part I. Springer LNCS 14780, pp. 1--23, Sept 2024
Assessing Confidence in Assurance 2.0 by Robin Bloomfield and John Rushby, Technical Report SRI-CSL-2022-02, May 2022 and also available as arXiv 2205.04522, both revised May 2024
Defeaters and Eliminative Argumentation in Assurance 2.0 by Robin Bloomfield, Kate Netkachova, and John Rushby, Technical Report SRI-CSL-2024-01, May 2024; also available as arXiv 2405.15800.
Assurance 2.0: A Manifesto by Robin Bloomfield and John Rushby, keynote presentation at 29th Safety-Critical Systems Symposium (SSS'21), February 2021. Draft available as arXiv 2004.10474

An overview of my other papers on assurance

Clarissa/ASCE Tool support for Assurance 2.0

Honeywell, Adelard (now part of NCC Group), SRI, and UT Dallas

Clarissa is a tool suite that supports Assurance 2.0. It builds on Adelard's ASCE and Clarissa/ASCE is available from Adelard: see the CAE website.

Clarissa supports the construction and evaluation of assurance cases using Assurance 2.0, and provides tools for logical and probabilistic assessment, defeaters, and residual doubts. It also has a synthesis assistant that can synthesize assurance (sub)cases from templates provided in a theory.

In addition Clarissa has tools for exploring semantic properties. It can use an LLM to translate claims into a logical representation, then perform reasoning using Answer Set Programming with s(CASP) to examine properties such as consistency, certain forms of well-formedness, and completeness.

Enabling Theory-based Continuous Assurance: A Coherent Approach with Semantics and Automated Synthesis, by Srivatsan Varadarajan et al. Presented at SASSUR Workshop, Sept 2024, published in SafeComp Workshops, Springer LNCS 14989. pp 173--187
Automating Semantic Analysis of System Assurance Cases using Goal-directed ASP by Anitha Murugesan et al. To appear in special issue of TPLP but already available at arXiv 2408.11699.
CLARISSA: Foundations, Tools & Automation for Assurance Cases by Srivatsan Varadarajan et al. Presented at DASC 23, Barcelona Spain, October 2023

Return to my bibliography page.

John Rushby (R u s h b y @ c s l . s r i . c o m)