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From: olcott <polcott333@gmail.com>
Newsgroups: comp.theory
Subject: Re: Every sufficiently competent C programmer knows
Date: Mon, 10 Mar 2025 21:27:42 -0500
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On 3/10/2025 9:21 PM, Richard Damon wrote:
> On 3/10/25 7:41 PM, olcott wrote:
>> 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.
>>
>> Since HHH does see that same pattern that competent
>> C programmers see it correctly aborts its emulation
>> and rejects these inputs as non terminating.
>>
> 
> Problem: DD Isn't a program, and if you try to compile it, you will get 
> an undiefined symbol HHH.
> 

HHH need not be a program for this correct thought experiment.
The only detail required to know about HHH is that it correctly
emulates N steps of DD.


-- 
Copyright 2025 Olcott "Talent hits a target no one else can hit; Genius
hits a target no one else can see." Arthur Schopenhauer