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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: Anyone with sufficient knowledge of C knows that DD specifies non-terminating behavior to HHH
Date: Thu, 20 Feb 2025 10:43:45 +0200
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On 2025-02-20 00:31:33 +0000, olcott said:

> On 2/19/2025 3:01 AM, Mikko wrote:
>> On 2025-02-18 11:26:25 +0000, olcott said:
>> 
>>> On 2/18/2025 3:24 AM, Mikko wrote:
>>>> On 2025-02-17 09:05:42 +0000, Fred. Zwarts said:
>>>> 
>>>>> Op 16.feb.2025 om 23:51 schreef olcott:
>>>>>> On 2/16/2025 4:30 PM, joes wrote:
>>>>>>> Am Sun, 16 Feb 2025 15:58:14 -0600 schrieb olcott:
>>>>>>>> On 2/16/2025 2:02 PM, joes wrote:
>>>>>>>>> Am Sun, 16 Feb 2025 13:24:14 -0600 schrieb olcott:
>>>>>>>>>> On 2/16/2025 10:35 AM, joes wrote:
>>>>>>>>>>> Am Sun, 16 Feb 2025 06:51:12 -0600 schrieb olcott:
>>>>>>>>>>>> On 2/15/2025 2:49 AM, Mikko wrote:
>>>>>>>>>>>>> On 2025-02-14 12:40:04 +0000, olcott said:
>>>>>>>>>>>>>> On 2/14/2025 2:58 AM, Mikko wrote:
>>>>>>>>>>>>>>> On 2025-02-14 00:07:23 +0000, olcott said:
>>>>>>>>>>>>>>>> On 2/13/2025 3:20 AM, Mikko wrote:
>>>>>>>>>>>>>>>>> On 2025-02-13 04:21:34 +0000, olcott said:
>>>>>>>>>>>>>>>>>> On 2/12/2025 4:04 AM, Mikko wrote:
>>>>>>>>>>>>>>>>>>> On 2025-02-11 14:41:38 +0000, olcott said:
>>>>>>> 
>>>>>>>>>>>>>> DD  correctly simulated by HHH cannot possibly terminate normally.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> That claim has already shown to be false. Nothing above shows that
>>>>>>>>>>>>> HHH does not return 0. If it does DD also returns 0.
>>>>>>>>>>>> When we are referring to the above DD simulated by HHH and not
>>>>>>>>>>>> trying to get away with changing the subject to some other DD
>>>>>>>>>>>> somewhere else
>>>>>>>>>>> such as one that calls a non-aborting version of HHH
>>>>>>>>>>> 
>>>>>>>>>>>> then anyone with sufficient knowledge of C programming knows that no
>>>>>>>>>>>> instance of DD shown above simulated by any corresponding instance
>>>>>>>>>>>> of HHH can possibly terminate normally.
>>>>>>>>>>> Well, then that corresponding (by what?) HHH isn’t a decider.
>>>>>>>>>> I am focusing on the isomorphic notion of a termination analyzer.
>>>>>>>>> (There are other deciders that are not termination analysers.)
>>>>>>>>> 
>>>>>>>>>> A simulating termination analyzer correctly rejects any input that
>>>>>>>>>> must be aborted to prevent its own non-termination.
>>>>>>>>> Yes, in particular itself is not such an input, because we *know* that
>>>>>>>>> it halts, because it is a decider. You can’t have your cake and eat it
>>>>>>>>> too.
>>>>>>>> I am not even using the confusing term "halts".
>>>>>>>> Instead I am using in its place "terminates normally".
>>>>>>>> DD correctly simulated by HHH cannot possibly terminate normally.
>>>>>>> What’s confusing about „halts”? I find it clearer as it does not imply
>>>>>>> an ambiguous „abnormal termination”. How does HHH simulate DD
>>>>>>> terminating abnormally, then? Why doesn’t it terminate abnormally
>>>>>>> itself?
>>>>>>> You can substitute the term: the input DD to HHH does not need to be
>>>>>>> aborted, because the simulated decider terminates.
>>>>>>> 
>>>>>> 
>>>>>> typedef void (*ptr)();
>>>>>> int HHH(ptr P);
>>>>>> 
>>>>>> int DD()
>>>>>> {
>>>>>>   int Halt_Status = HHH(DD);
>>>>>>   if (Halt_Status)
>>>>>>     HERE: goto HERE;
>>>>>>   return Halt_Status;
>>>>>> }
>>>>>> 
>>>>>> int main()
>>>>>> {
>>>>>>   HHH(DD);
>>>>>> }
>>>>>> 
>>>>>> Every simulated input that must be aborted to
>>>>>> prevent the non-termination of HHH is stipulated
>>>>>> to be correctly rejected by HHH as non-terminating.
>>>>>> 
>>>>> A very strange and invalid stipulation.
>>>> 
>>>> It merely means that the words do not have their ordinary meaning.
>>> 
>>> Unless HHH(DD) aborts its simulation of DD itself cannot possibly 
>>> terminate normally.
>> 
>> That cannot be determined without examination of HHH, which is not in the
>> scope of OP.
> 
> I have given everyone here all of the complete source
> code for a few years

OP did not specify that HHH means that code. It is possible to compile
the code shown by OP and link it with another program that has the
name HHH. The resulting program may halt but that cannot be determined
from the shown DD.

-- 
Mikko