Re: Alan Turing's Halting Problem is incorrectly formed (PART-TWO)

From: Aatu Koskensilta (aatu.koskensilta_at_xortec.fi)
Date: 06/24/04 

Date: Thu, 24 Jun 2004 11:40:57 +0300

Peter Olcott wrote:
>"Aatu Koskensilta" <aatu.koskensilta@xortec.fi> wrote in message
>news:mcfCc.2619$je2.332@reader1.news.jippii.net...
>>Ullrich can't answer the question correctly if you specify that
>>WillHalt(x,y) = Ullrich's answer. If he answers "Yes" then the correct
>>answer is "No" and vice versa. That does not mean that there is no
>>correct answer, only that Ullrich can't give it.
>
>
> Yeah, Right! Just like there is a correct answer to the last digit of PI,
> except that no one anywhere, on the Earth or in Heaven above, can
> give this correct answer.

Only Ullrich is unable to give the correct answer. The rest of us can
give the correct answer as soon as we find out what Ullrich answers.

Consider the following question, to which only 'yes' or 'no' will be
accepted as an answer:

  Will Peter Olcott answer this question to the negative?

If you choose to not answer to the question, the answer will obviously
be "no". If you answer the question affirmatively, the answer will be
"no", and if you answer it to the negative, the answer will be "yes".
Whatever you answer, it will be wrong, but that doesn't change the fact
that the question does have a correct answer - which we don't presently
know, of course, since we lack the ability to predict your behaviour.

In contrast the question about the last digit of PI does not have an
answer since there is no such thing as the last digit of PI. 

-- 
Aatu Koskensilta (aatu.koskensilta@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
  - Ludwig Wittgenstein, Tractatus Logico-Philosophicus

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