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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: DDD emulated by HHH diverges from DDD emulated by HHH1
Date: Fri, 6 Jun 2025 11:45:44 +0300
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On 2025-06-04 14:52:50 +0000, olcott said:

> On 6/4/2025 1:54 AM, Mikko wrote:
>> On 2025-06-03 19:57:09 +0000, olcott said:
>> 
>>> On 6/3/2025 2:37 AM, Mikko wrote:
>>>> On 2025-06-02 15:52:53 +0000, olcott said:
>>>> 
>>>>> DDD correctly emulated by HHH diverges from DDD
>>>>> correctly emulated by HHH1 as soon as HHH begins
>>>>> emulating itself emulating DDD, marked below.
>>>> 
>>>> The DDD emulated (correctly or otherwise) by HHH is the same DDD as
>>>> the one emulated (correctly or otherwise) so both specify the same
>>>> behaviour.
>>> 
>>> No they do not. When DDD calls its own emulator its behavior
>>> is different than when DDD calls another different emulator.
>> 
>> If the input string does not unambiguously specify one and only one
>> behaviour it is incorrectly encoded and not a valid input string.
>> The halting problem of Truing machines requires that every pair of
>> a Turing macnine and input is descibed so that the behaviour to
>> be decided about is the only behaviour that meets to the description.
>> 
> 
> The code proves what it proves.

Which is nothing. However, it is quite obvious from the C code
and clear enough form the assembly code that DDD does halt if
HHH(DDD) halts. That HHH(DDD) halts is not obvious from the
code but has been varified both with an exectuion of HHH(DDD)
and with an exectuion of DDD. The latter also verifies that
DDD halts, so the obvious inference from the code is redundant.

> _DDD()
> [00002183] 55             push ebp
> [00002184] 8bec           mov ebp,esp
> [00002186] 6883210000     push 00002183 ; push DDD
> [0000218b] e833f4ffff     call 000015c3 ; call HHH
> [00002190] 83c404         add esp,+04
> [00002193] 5d             pop ebp
> [00002194] c3             ret
> Size in bytes:(0018) [00002194]
> 
> _main()
> [000021a3] 55             push ebp
> [000021a4] 8bec           mov ebp,esp
> [000021a6] 6883210000     push 00002183 ; push DDD
> [000021ab] e843f3ffff     call 000014f3 ; call HHH1
> [000021b0] 83c404         add esp,+04
> [000021b3] 33c0           xor eax,eax
> [000021b5] 5d             pop ebp
> [000021b6] c3             ret
> Size in bytes:(0020) [000021b6]

-- 
Mikko