Re: [SystemSafety] Fault, Failure and Reliability Again (short)

From: Peter Bernard Ladkin < >
Date: Wed, 04 Mar 2015 09:57:50 +0100


a partial reply to Nick is at

John Knight said he uses the Laprie taxonomy (as the 2004 paper referenced by Örjan yesterday is known) in his book, precisely in order to keep straight on such matters as we have been discussing. I took John's suggestion in my blog post. Software failure, software fault, software error, and software reliability are given a clear meaning in the Laprie taxonomy, although it is not determined how one may measure software reliability.

Since the Laprie taxonomy is the result of decades of deliberate in IFIP WG 10.4 which first resulted in a book, before this paper, it should by no means be dismissed lightly.

This decisively contradicts Nick's proposal that

On 2015-03-03 22:50 , Nick Tudor wrote:
> .....the software does not fail, the system does. It therefore makes no sense to talk about
> reliability of software

Nick has suggested privately that this view is prevalent in aerospace, and I am informed indirectly that it is also prevalent in some areas of the nuclear industry. If so, it is surely a matter of engineering reasonsibility due diligence that these engineers get themselves up to date on the concepts the experts, the computer scientists, use to talk about their subject matter.

PBL Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany Je suis Charlie
Tel+msg +49 (0)521 880 7319

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Received on Wed Mar 04 2015 - 09:57:55 CET

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