Robin Bloomfield and John Rushby

Presented at SafeComp 2026, Valencia Spain, September 2026 and published in Springer LNCS 16868, pp. 279-295.

Abstract

It exploits the ways claims are decomposed in a structured argument and provides different approaches according to the different degrees of (in)dependence and diversity among subclaims, and how they eliminate the concerns that undermine confidence in their parent claims. The method uses only elementary probabilistic constructions that are well-known in other contexts (e.g., Fréchet bounds) but we interpret and apply them in a manner that is specifically focused on assurance arguments and requires no background in probabilistic analysis.

We show that the method is not susceptible to counterexamples that Graydon and Holloway exhibit for other approaches to quantifying confidence and we recommend it as an additional tool and point of view in assessing Assurance 2.0 arguments that can contribute to dialectical examination and evaluation of cost/confidence tradeoffs for different risk levels and the overall balance of confidence across a structured argument.

Paper

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BibTeX Entry

@string{lncs = {Lecture Notes in Computer Science}}
@string{sv = {Springer-Verlag}}
@string{safecomp = {Computer Safety, Reliability, and Security {\sc (SafeComp)}}}

@inproceedings{Bloomfield&Rushby:SafeComp26,
  title={Probabilistic Confidence In {Assurance 2.0} Arguments},
  author = {Robin Bloomfield and John Rushby},
  booktitle= safecomp,
  pages={279--295},
  address = {Valencia, Spain},
  publisher = sv,
  series = lncs,
  volume = 16868,
  month = sep,
  year= 2026
}