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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.lang.c
Subject: Re: Every D(D) simulated by H presents non-halting behavior to H ###
Date: Fri, 24 May 2024 13:08:55 +0300
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On 2024-05-23 13:09:01 +0000, olcott said:

> On 5/23/2024 3:23 AM, Mikko wrote:
>> On 2024-05-22 14:59:24 +0000, olcott said:
>> 
>>> On 5/22/2024 3:50 AM, David Brown wrote:
>>>> On 21/05/2024 22:13, Keith Thompson wrote:
>>>>> David Brown <david.brown@hesbynett.no> writes:
>>>>> [...]
>>>>>> However, my point was that the common excuse of "I hate this crime so
>>>>>> much I lashed out" is not a valid excuse.
>>>>> [...]
>>>>> 
>>>>> And you could have made that point without accompanying it by a long
>>>>> article about various kinds of child abuse in a newsgroup that's
>>>>> supposed to be about C.
>>>>> 
>>>>> You didn't have to let yourself be trolled.
>>>>> 
>>>> 
>>>> I don't consider James' post to be trolling.  But of course that in 
>>>> itself does not mean it is appropriate to reply here.  However, I 
>>>> replied to that post in the group (rather than email) because it seemed 
>>>> to me that a point I had made previously needed clarification.
>>>> 
>>>> As has been pointed out by others, topicality in this thread was doomed 
>>>> from the first post.  I'd be happier if Olcott had never cross-posted 
>>>> here, but we can't change that.
>>>> 
>>> 
>>> *Someone could simply answer the question instead of*
>>> *spending countless messages on dodging the question*
>>> 
>>> For every H/D pair matching the following template where
>>> H is a pure function:
>>> 
>>> Does any D correctly simulated by H reach its own line 06 and
>>> halt or does the fact that D remains stuck in recursive simulation
>>> prevent that?
>>> 
>>> typedef int (*ptr)();  // ptr is pointer to int function in C
>>> 00       int H(ptr p, ptr i);
>>> 01       int D(ptr p)
>>> 02       {
>>> 03         int Halt_Status = H(p, p);
>>> 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       }
>>> 
>>> It is trivial to see that for every H/D pair of the infinite
>>> set of H/D pairs that match the above template that
>>> 
>>> D correctly simulated by H cannot possibly reach its own final
>>> state at line 06 and halt because D correctly simulated by
>>> H remains stuck in recursive simulation.
>>> 
>>> This provides the basis for simulating termination analyzer H to
>>> correctly determine that the halting problem's counter-example
>>> input D cannot possibly halt.
>> 
>> Someone already pointed out that the question is ill-posed (undefined
>> and insonsistently used symbols). No reason to expect any other answer.
>> 
> 
> That assessment can only come from not carefully looking at what I said.
> It is dead obvious that D correctly simulated by H remains stuck in
> recursive simulation thus cannot possibly reach its own line 06 and
> halt.

That is possible. What you said is scattered over so many messages
that nobody can be expedted to carefully look at all of them.

-- 
Mikko