Re: [SystemSafety] Does "reliable" mean "safe" and or "secure" or neither?

From: Roberto Bagnara < >
Date: Sun, 24 Apr 2016 18:00:02 +0200

On 24/04/2016 11:13, Michael J. Pont wrote:
> Overall, I think this is a great list (and I think that PBL deserves a medal
> for the work he does on it).

I think the same.

> In terms of the most recent discussion (that gave rise to your comment),
> "software reliability" doesn't make sense to me as a label (because the
> software does not change / wear out).

Please help me understand. Suppose we have a system that is composed by a number of interacting components. Suppose also that such components are black boxes: we cannot look inside them. However, we know everything about the interactions between the components because we can monitor them with precision. Suppose we also have specifications of each component that are detailed enough so that, in case of system failure/misbehavior, we are able to point the finger at small sets of components and tell which component(s) originated the first out-of-spec behavior, which component(s) that were meant to mitigate this misbehavior failed to do so, and so on.

My question is:

  Can we talk about the reliability of the components in the context   of the overall system, without any knowledge about how they implement   their functionality (e.g., hardware only, hardware + little bit of   software, hardware + lots of software, hardware + software + humans)?

Kind regards,


     Prof. Roberto Bagnara

Applied Formal Methods Laboratory - University of Parma, Italy
                              BUGSENG srl -
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Received on Sun Apr 24 2016 - 18:01:10 CEST

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