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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: Every D correctly simulated by H never reaches its final state and halts
Date: Sat, 18 May 2024 12:45:07 +0300
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On 2024-05-17 15:55:03 +0000, olcott said:
> On 5/17/2024 4:08 AM, Mikko wrote:
>> On 2024-05-17 07:25:52 +0000, Fred. Zwarts said:
>>
>>> Op 17.mei.2024 om 03:15 schreef olcott:
>>>> The following is self-evidently true on the basis of the
>>>> semantics of the C programming language.
>>>>
>>>> typedef int (*ptr)(); // ptr is pointer to int function
>>>> 00 int H(ptr x, ptr x);
>>>> 01 int D(ptr x)
>>>> 02 {
>>>> 03 int Halt_Status = H(x, x);
>>>> 04 if (Halt_Status)
>>>> 05 HERE: goto HERE;
>>>> 06 return Halt_Status;
>>>> 07 }
>>>> 08
>>>> 09 int main()
>>>> 10 {
>>>> 11 H(D,D);
>>>> 12 return 0;
>>>> 13 }
>>>>
>>>> In the above case a simulator is an x86 emulator that correctly
>>>> emulates at least one of the x86 instructions of D in the order
>>>> specified by the x86 instructions of D.
>>>>
>>>> This may include correctly emulating the x86 instructions of H
>>>> in the order specified by the x86 instructions of H thus calling
>>>> H(D,D) in recursive simulation.
>>>>
>>>> Any H/D pair matching the above template where
>>>> D(D) is simulated by the same H(D,D) that it calls
>>>> cannot possibly reach its own line 06 and halt.
>>>>
>>>> *This is a simple software engineering verified fact*
>>>>
>>>
>>> Note that olcott defines 'verified fact' as 'proven fact', but he is
>>> unable to show the proof. So, it must be read as 'my belief'.
>>
>> A "proven fact" without a proof is not worse than a "verified fact"
>> without a verification.
>>
>
> *I updated my wording*
> It is self-evidently true to anyone having sufficient knowledge
> of the semantics of the C programming language.
No, it is not. I would know if it were.
--
Mikko