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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: Every D(D) simulated by H presents non-halting behavior to H ###
Date: Wed, 15 May 2024 11:18:26 +0300
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On 2024-05-14 14:35:42 +0000, olcott said:

> On 5/14/2024 4:52 AM, Mikko wrote:
>> On 2024-05-13 14:43:09 +0000, olcott said:
>> 
>>> On 5/13/2024 4:14 AM, Mikko wrote:
>>>> On 2024-05-13 04:54:30 +0000, immibis said:
>>>> 
>>>>> On 10/05/24 19:55, Alan Mackenzie wrote:
>>>>>> [ Followup-To: set ]
>>>>>> 
>>>>>> In comp.theory olcott <polcott333@gmail.com> wrote:
>>>>>> 
>>>>>> [ .... ]
>>>>>> 
>>>>>> I've tried out your much spammed code on GCC (see below).  It is clear
>>>>>> you have never built or run this code, which ironically can't reach Line
>>>>>> 06.  It can't even reach line 00.
>>>>>> 
>>>>>>> Richard tried to get away with D never simulated by H as an example
>>>>>>> of D simulated by H:
>>>>>> 
>>>>>>> Message-ID: <v0ummt$2qov3$2@i2pn2.org>
>>>>>>> On 5/1/2024 7:28 PM, Richard Damon wrote:
>>>>>> 
>>>>>>> *That people say they know I am wrong yet will not show the detailed*
>>>>>>> *steps of how I am wrong indicates that they are probably liars*
>>>>>> 
>>>>>> You have said, or at least implied that your code fragment is runnable.
>>>>>> I think you are the liar, here.
>>>>>> 
>>>>>>> 00 int H(ptr x, ptr x)  // ptr is pointer to int function
>>>>>>> 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 }
>>>>>> 
>>>>>> 
>>>>>> .  These are the diagnostics generated by GCC:
>>>>>> 
>>>>> And the halting problem is about Turing machines, anyway.
>>>> 
>>>> Not necessarily. The same question can be asked about different machines.
>>>> The restriction to Turing machines is just one way to ensure that the
>>>> problem is well defined.
>>>> 
>>> 
>>> Well put. All computable functions even if written in C.
>> 
>> You still must ensure that the problem is well defined. With C there is
>> the problem that conforming C programs often fail to be strictly conforming.
>> If a program is not strictly conforming it may be interpreted as halting
>> by some implementation and non-halting or incorrect by another.
>> 
> 
> 00 int H(ptr x, ptr x)  // ptr is pointer to int function
> 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 }
> 
> One can correctly determine that every D simulated by H
> never reaches past its own line 03.

That is not strictly conforming and hardly conforming at all.

-- 
Mikko