Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Richard Heathfield <rjh@cpax.org.uk>
Newsgroups: comp.theory
Subject: Re: Halting Problem: What Constitutes Pathological Input
Date: Mon, 5 May 2025 21:53:10 +0100
Organization: Fix this later
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On 05/05/2025 20:38, olcott wrote:
> On 5/5/2025 2:23 PM, Richard Heathfield wrote:
>> On 05/05/2025 20:20, olcott wrote:
>>> Is "halts" the correct answer for H to return?  NO
>>> Is "does not halt" the correct answer for H to return?  NO
>>> Both Boolean return values are the wrong answer
>>
>> Or to put it another way, the answer is undecidable, QED.
>>
>> See? You got there in the end.
>>
> 
> Is this sentence true or false: "What time is it?"

20:45GMT, give or take.

> is also "undecidable" because it is not a proposition
> having a truth value.

No, it's computable and therefore decidable. Your computer is 
perfectly capable of displaying its interpretation of the time.

> Is this sentence true or false: "This sentence is untrue."
> is also "undecidable" because it is not a semantically sound
> proposition having a truth value.

But we know that it halts at the full stop.

> Can Carol correctly answer “no” to this (yes/no) question?

You have, I see, learned that not all yes/no questions are 
decidable. Well done! You're coming along nicely.

> Both Yes and No are the wrong answer proving that
> the question is incorrect when the context of who
> is asked is understood to be a linguistically required
> aspect of the full meaning of the question.

The question is grammatically and syntactically unremarkable. I 
see no grounds for claiming that it's 'incorrect'. It's just 
undecidable.

You appear to be trying to overturn the Halting Problem by 
claiming that Turing somehow cheated. You're entitled to hold 
that opinion, but it's not one that will gain any traction with 
peer reviewers when you try to publish.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within