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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: Thu, 29 Aug 2024 19:22:03 +0200
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Op 29.aug.2024 om 16:07 schreef olcott:
> On 8/29/2024 2:17 AM, Mikko wrote:
>> On 2024-08-28 12:08:06 +0000, olcott said:
>>
>>> On 8/28/2024 2:39 AM, Mikko wrote:
>>>> On 2024-08-27 12:44:31 +0000, olcott said:
>>>>
>>>>> On 8/27/2024 3:38 AM, Fred. Zwarts wrote:
>>>>>> 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.
>>>>>
>>>>> A straw man fallacy (sometimes written as strawman) is the informal 
>>>>> fallacy of refuting an argument different from the one actually 
>>>>> under discussion...
>>>>> https://en.wikipedia.org/wiki/Straw_man
>>>>
>>>> You should also point a link to the equivocation fallacy. You use it
>>>> more often than straw man.
>>>
>>> Isomorphism is not equivocation
>>
>> The use of HHH for many purposes (a specific program, an unpsecified
>> memeber of a set of programs, a hypothetical program) is.
>>
>> Your first posting looked like you were going to apply equivocation
>> later in the discussion. Now, after several later messages, it seems
>> that you want to apply the fallacy of "moving the goal posts" instead.
>>
> 
> void EEE()
> {
>    HERE: goto HERE;
>    return;
> }
> 
> HHH correctly predicts what the behavior of EEE would
> be if this HHH never aborted its emulation of EEE.
> 
> void DDD()
> {
>    HHH(DDD);
>    return;
> }
> 
> HHH correctly predicts what the behavior of DDD would
> be if this HHH never aborted its emulation of DDD.
Which is incorrect, because HHH is not allowed to change the input. The 
simulating HHH may abort, but it may not ignore the fact that the input 
(the simulated HHH) is coded to abort when it sees the 'special 
condition'. Otherwise it would decide about a non-input, which is not 
allowed.

In the same way as HHH is not allowed to change the code of EEE when it 
aborts EEE. The simulating HHH may abort and predict the behaviour of 
the *unchanged* input would be.

In other words: HHH should process its input as if it was not its own 
code. In fact, that is what HHH1 does and that is correct.