Stephan Neuhaus <[EMAIL PROTECTED]> writes:
> On Apr 28, 2008, at 23:56, Perry E. Metzger wrote:
>
>> If you have a rotten apple engineer, he will be able to hide what he's
>> trying to do and make it look completely legit. If he's really good,
>> it may not be possible to catch what he's done EVEN IN PRINCIPLE.
>
> Fred Cohen proved in 1984 in his "Computer Viruses, Theory and
> Experiments"[1] that "Program P is a virus" is undecidable.

He needn't have bothered. All non-trivial properties of programs
are undecidable. Rice's Theorem, you know. Such a proof is one line --
you need merely assert that "X is a virus" is a non-trivial property
(that is, a property that is only true of some programs).

Perry

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