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<p>Software in its operating environment does degrade over time. <br>
</p>
<ul>
<li>What was fit for purpose one year no longer is the year
following.</li>
<li>as vulnerabilities are discovered, shared and exploited,
failure rates increase</li>
<li>as software is maintained to fix known errors, the fault
density may steadily increase because the maintenance degrades
the artchitecture and more defects are introduced. (I have seen
this happen gradually to major software systems in my career).</li>
</ul>
<p>The failure rates can be determined statistically within
scientifically sound confidence levels. To me, "reliability"
carries the right message. It may be an imperfect analogy but many
words are. <br>
</p>
<p>Martyn<br>
</p>
<div class="moz-cite-prefix">On 15/09/2020 14:30, Michael Holloway
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAB_B+Ubi5sjwTj5ky4R2RrE5jWScksMZikXF9gj=YWQ2zA1iLA@mail.gmail.com">
<div class="gmail_default"
style="font-family:georgia,serif;font-size:large">o far too many
people (myself included) "reliability" necessarily includes
notions of either randomness (for example, given an identical
environment, history, design, and manufacturer, component A
fails but B does not) or degradation over time. Because neither
notion applies to conventional software, the phrase "software
reliability" is (and always will be) to me at best meaningless
and at worst misleading.</div>
<div class="gmail_default"
style="font-family:georgia,serif;font-size:large"><br>
</div>
</blockquote>
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