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From: dbush <dbush.mobile@gmail.com>
Newsgroups: comp.theory
Subject: Re: Every sufficiently competent C programmer knows --- Very Stupid
 Mistake or Liars
Date: Thu, 13 Mar 2025 11:09:11 -0400
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On 3/13/2025 11:04 AM, olcott wrote:
> void DDD()
> {
>    HHH(DDD);
>    return;
> }
> 
> When HHH correctly emulates N steps of the
> above DDD it cannot possibly reach its own
> "return" instruction and terminate normally.
> 

Irrelevant, as that's not what the halting problem is about.

> On 3/13/2025 8:55 AM, dbush wrote:
>> On 3/13/2025 9:41 AM, olcott wrote:
>>> I created DDD because
>>> some of my reviewers are not technically competent
>>> enough to see that line 2 of DD is unreachable code
>>> when N steps of DD are correctly simulated by HHH.
>>>
>>
>> But it *is* reachable code when DD is executed directly, 
> 
> Because the directly executed code like DDD correctly
> emulated by HHH1
> DOES NOT HAVE THE PATHOLOGICAL SELF-REFERENCE OF
> CALLING ITS OWN EMULATOR YOU NITWIT.
> 
> It is like you really really believe that sum(2,3) == 7
> even though the sum of 2 + 3 == 5.
> 

We don't care about the instance of DDD being simulated by a particular 
simulator.  We're interested in the hypothetical case where DDD is 
executed directly, which is what a solution to the halting problem is 
stipulated to report:


Given any algorithm (i.e. a fixed immutable sequence of instructions) X 
described as <X> with input Y:

A solution to the halting problem is an algorithm H that computes the 
following mapping:

(<X>,Y) maps to 1 if and only if X(Y) halts when executed directly
(<X>,Y) maps to 0 if and only if X(Y) does not halt when executed directly