[SystemSafety] Statistical Assessment of SW With Deliberate Unreliability for a SIL requirement

[Peter Bernard Ladkin]

I am working with others on a reformulation of IEC 61508 Part 7 Annex D, on the statistical
assessment of software presented with black-box functionality.

Rainer Faller brought up an interesting example. He has seen SW which is proposed to be used in a
safety-related application, which has a Safety Requirements Specification (SRS) in that application,
and which has a "Debug/Maintenance" mode, triggered by a specific input sequence known to the SW
developer of course, but not necessarily to the system developer who wishes to use it in the new
safety-related application.

Can such SW be presented as "black box" with statistical evidence of its fitness for purpose, and
accepted for use based on the statistical assessment?

I've written a White Paper on the case, RVS White Paper 8, available at
http://www.rvs.uni-bielefeld.de/publications/WhitePapers/LadkinFallerExample20150101.pdf

PBL

Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de