Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Richard Heathfield <rjh@cpax.org.uk>
Newsgroups: comp.theory
Subject: Re: Incorrect requirements --- Computing the mapping from the input
 to HHH(DD)
Date: Mon, 12 May 2025 19:06:48 +0100
Organization: Fix this later
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On 12/05/2025 18:03, Ben Bacarisse wrote:
> Richard Heathfield <rjh@cpax.org.uk> writes:
> 
>> On 12/05/2025 01:38, Mike Terry wrote:
>>> On 11/05/2025 18:11, Richard Heathfield wrote:
> ...
>>>> we have an undecidable computation,
>>> No no, that doesn't make sense.
>>
>> Agreed. Therefore, even *after* taking out all the dodgy code, the decider
>> must be broken.
>>
>>>   DD stops, and there are lots of partial halt deciders that will decide
>>> that particular input correctly.  PO's DD isn't "undecidable".
>>
>> I hear what you're saying (or at least I see what you typed), but if DD's
>> result is so decidable, how come his decider can't correctly decide?
> 
> This is just a misunderstand about terms.  The fact that some program
> gets the answer wrong does not mean that this case is not (correctly)
> decidable.

I beg you to forgive a little levity. I was just rather amused 
that a program so utterly devoted to overturning a decidability 
proof seems quite unable to make a decision.


-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
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