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From: "Fred. Zwarts" <F.Zwarts@HetNet.nl>
Newsgroups: comp.theory
Subject: Re: DDD emulated by HHH --- (does not refer to prior posts)
Date: Tue, 27 Aug 2024 10:38:24 +0200
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Op 27.aug.2024 om 04:33 schreef olcott:
> This is intended to be a stand-alone post that does not
> reference anything else mentioned in any other posts.
> 
> void DDD()
> {
>    HHH(DDD);
>    return;
> }
> 
> _DDD()
> [00002172] 55         push ebp      ; housekeeping
> [00002173] 8bec       mov ebp,esp   ; housekeeping
> [00002175] 6872210000 push 00002172 ; push DDD
> [0000217a] e853f4ffff call 000015d2 ; call HHH(DDD)
> [0000217f] 83c404     add esp,+04
> [00002182] 5d         pop ebp
> [00002183] c3         ret
> Size in bytes:(0018) [00002183]
> 
> When we assume that:
> (a) HHH is an x86 emulator that is in the same memory space as DDD.
> (b) HHH emulates DDD according to the semantics of the x86 language.
> 
> then we can see that DDD emulated by HHH cannot possibly get past
> its own machine address 0000217a.
> 


Yes, we see. In fact DDD is not needed at all.
In the following program

        int main() {
          return HHH(main);
        }

HHH cannot possibly simulate itself up to the end of itself. Still HHH 
halts, which proves that there is an end. The only conclusion is, that 
the simulation is incomplete and therefore incorrect.
Further it is incorrect to think that the fact that the simulation halts 
too soon is an indication for non-halting behaviour. The analysis of 
that 'special condition' is the real problem, not the partial incorrect 
simulation.