[SystemSafety] What do we know about software reliability?

[Peter Bernard Ladkin]

After nine messages from Derek Jones, with the only substantial content a link to his favorite work
in software reliability, a paper from 38 years ago, I had hoped Peter Bishop's useful intervention
had raised the level of discourse.

Then this.

On 2020-09-15 11:00 , Nick Tudor wrote:
> ... There is (at last) a distinct but still tacit acceptance that it is a
> nonsense to accept software has a 'reliability' 



Please, let's bag the derogative one-word dismissals of a justifiably thriving area of software
engineering.

>.. outdated research for which the foundations are highly questionable.  This is now
> gaining acceptance rather than a statistical approach.  


The product of limited experience, maybe?

See Chapters 16 and 19 of the rail RAMS Handbook
https://www.routledgehandbooks.com/doi/10.1201/b21983 . The Handbook was published in 2018. This is
new stuff.

Far from dying out, it is actively pursued, by European law, in rail automation. Are people aware of
the European rail Common Safety Methods (CSM), which require a numerics-based approach to equipment
risk? https://www.era.europa.eu/can-we-help-you/faq/296_en

Besides, as long as 14 CFR 25.1309/CS 25.1309 read as they do, a partial risk-matrix approach (which
requires components to be evaluated for probability of failure) is also required in civil aeronautics.

> As I recall, I have said before on this list, software has no wear out mechanism so software
> reliability is somewhat meaningless. 

Yes, you did say that. Can we raise the level of discourse above name-calling?

[I might add, that I remember you told the 8th winner of Software Engineering's highest award, in
public, that he had been wasting his professional life on a chimera. If that is the kind of
discourse you favor, you can't justifiably complain when others such as myself respond in kind. I
suggest you change your approach this time around.]

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
Styelfy Bleibgsnd
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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