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From: Richard Heathfield <rjh@cpax.org.uk>
Newsgroups: comp.theory
Subject: Re: Every sufficiently competent C programmer knows
Date: Tue, 11 Mar 2025 13:46:19 +0000
Organization: Fix this later
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On 11/03/2025 13:31, olcott wrote:
> On 3/11/2025 5:28 AM, Mikko wrote:
>> On 2025-03-10 23:41:13 +0000, olcott said:
>>
>>> typedef void (*ptr)();
>>> int HHH(ptr P);
>>>
>>> void Infinite_Loop()
>>> {
>>>    HERE: goto HERE;
>>>    return;
>>> }
>>>
>>> void Infinite_Recursion()
>>> {
>>>    Infinite_Recursion();
>>>    return;
>>> }
>>>
>>> void DDD()
>>> {
>>>    HHH(DDD);
>>>    return;
>>> }
>>>
>>> int DD()
>>> {
>>>    int Halt_Status = HHH(DD);
>>>    if (Halt_Status)
>>>      HERE: goto HERE;
>>>    return Halt_Status;
>>> }
>>>
>>> That when HHH correctly emulates N steps of the
>>> above functions that none of these functions can
>>> possibly reach their own "return" instruction
>>> and terminate normally.
>>
>> Every competent programmer knows that the information given is
>> insufficient to determine whether HHH emulates at all, and whether
>> it emulates correctly if it does.
>>
>>> Since HHH does see that same pattern that competent
>>> C programmers see it correctly aborts its emulation
>>> and rejects these inputs as non terminating.
>>
>> Whether HHH does see those patterns cannot be inferred from the 
>> information
>> given. Only about DDD one can see that it halts if HHH returns. 
>> In addition,
>> the given information does not tell whether HHH can see 
>> patterns that are
>> not there.
>>
>> How many competent programmers you have asked?
>>
> 
> Two C programmers with masters degrees in computer science
> agree that DDD correctly emulated by HHH cannot possibly
> reach its own "return" instruction and terminate normally.

Bring 'em on. Perhaps /they/ have the source to HHH, because 
without it you don't have anything. (And btw whatever it is you 
claim to have is far from clear, because all I've seen so far is 
an attempt to express the Halting Problem in C and pseuodocode, 
where the pseudocode reads: HHH(){ magic happens }

> 

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
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