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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: Overcoming the proof of undecidability of the Halting Problem by a simple example in C
Date: Mon, 19 May 2025 12:41:11 +0300
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On 2025-05-19 01:24:06 +0000, olcott said:

> On 5/18/2025 8:02 PM, Richard Heathfield wrote:
>> On 19/05/2025 01:33, olcott wrote:
>>> On 5/18/2025 7:27 PM, Ben Bacarisse wrote:
>>>> Richard Heathfield <rjh@cpax.org.uk> writes:
>> 
>> [Apologies for not snipping. This one was hard to know how best to edit down.]
>> 
>>>> 
>>>>> On 18/05/2025 23:18, Ben Bacarisse wrote:
>>>>>> Richard Heathfield <rjh@cpax.org.uk> writes:
>>>>>> ...
>>>>>>> If they know C they should know that it's
>>>>>>>    u32 HHH(void (*P)()), according to Halt7.c.
>>>>>>> 
>>>>>>> It takes a pointer to a function that accepts no arguments and returns no
>>>>>>> value.
>>>>>> Yes, but I am surprised that you are being so modern!!  You used to
>>>>>> favour C90 and didn't really care for anything more recent.
>>>>> 
>>>>> I am just as surprised that you missed the distinction I was making, which
>>>>> was between these:
>>>>> 
>>>>> void HHH(void (*f)(void))
>>>>> u32 HHH(void (*P)())
>>>>> 
>>>>> Empty parentheses had nothing to do with my point. On line 16 we find:
>>>>> typedef uint32_t u32;
>>>>> 
>>>>> uint32_t != void.
>>>> 
>>>> Yes, I got the distinction you were making, but I must have got confused
>>>> about the referent of "it" in the part I quoted.  I was hoping to add
>>>> to the discussion despite ignoring your main point.  Sorry.
>>>> 
>>> 
>>> *Copied from the original post that he responded to*
>>> 
>>> int DD()
>>>   {
>>>    int Halt_Status = HHH(DD);
>>>    if (Halt_Status)
>>>      HERE: goto HERE;
>>>    return Halt_Status;
>>>   }
>> 
>> Not so. The post I responded to was Message-ID: <1009lm9$b15q$1@dont- email.me>
>> 
>> There was a lot of quoted material, none of which mentioned int DD(), 
>> although it did mention a void DDD().
>> 
>> The only original material was:
>> 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> No, there are peole who do know C but don't know that HHH is not
>> void HHH(void (*f)(void)) {} and how therefore cannot tell that
>> HHH does simulate DDD.
> 
> It was stipulated that HHH does simulate DDD.
> No need to check every little punctuation mark.

Not in the message about what people who know C know. There are
people who know C but not your stipulations.

-- 
Mikko