[SystemSafety] Functional hazard analysis, does it work?

Wed Jan 20 07:35:32 CET 2016

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On 2016-01-19 13:31 , paul_e.bennett at topmail.co.uk wrote:
> 
> Completeness may be a difficult objective to prove in a mathematical sense but fortunately we
> are only required to utilise our best efforts in this regard, using the most up to date and
> emergent industry accepted techniques that are relevant to the development.

On 2016-01-20 03:20 , DREW Rae wrote:
> ...There's the internal completeness question discussed by Peter, which is in theory
> determinstic if and only if you can create a complete causal model of your system for the
> properties of interest, and keep it accurate.

Interesting. I suggest an obviously desirable criterion for an effective HazAn (judging by the
amount of time it takes up in hazard analysis meetings), and that there are techniques available
for (often, sometimes, occasionally) ensuring it.

There are two reactions. One is "that's *math*, thank goodness we don't have to do it!" The other
is "it'll work if [you have all this information that no one ever has]." Neither of these
gentlemen has, to my knowledge, ever performed an OHA.

For thirty years, I've heard the refrain that "formal methods don't work", or, in a subtler
version "formal methods may work if you can do all this stuff which math geeks can do, but none of
us can so they're impractical". Meanwhile, it has become possible to deliver critical software
which is demonstrably free of run-time error, which thirty years ago was not possible.

Multiple firms offer that capability. It has become feasible, indeed routine, through the use of
those methods which "don't work", that are "stuff which math geeks can do" and are "impractical."

Isn't it time we started embracing straightforward methods which enable us to do things which we
otherwise cannot do? To say, rather, "that sounds interesting - I'd like to try it!"

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