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From: "Fred. Zwarts" <F.Zwarts@HetNet.nl>
Newsgroups: comp.theory
Subject: Re: Every sufficiently competent C programmer knows
Date: Tue, 11 Mar 2025 17:41:35 +0100
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Op 11.mrt.2025 om 14:31 schreef olcott:
> 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.
> 

It is clear that that HHH cannot possibly simulate itself up to the end.
DD is not even needed to see that:

Olcott has admitted that in:

        int main() {
          return HHH(main);
        }

HHH returns and reports that it cannot possibly reach the 'return' 
instruction in its simulation.
So, what is the purpose of a simulation that is not able to reach the 
end, in particular when direct execution and world-class simulators have 
no problem to reach that end?