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From: olcott <polcott333@gmail.com>
Newsgroups: comp.theory
Subject: Re: How to write a self-referencial TM?
Date: Tue, 20 May 2025 23:33:15 -0500
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On 5/19/2025 7:29 AM, Mikko wrote:
> On 2025-05-19 04:07:11 +0000, olcott said:
> 
>> On 5/18/2025 10:21 PM, André G. Isaak wrote:
>>> On 2025-05-18 16:08, olcott wrote:
>>>> On 5/18/2025 4:58 PM, André G. Isaak wrote:
>>>
>>>>> In English, both 'description' and 'specification' can refer to 
>>>>> something which is either complete or only partial.
>>>>>
>>>>
>>>> Description typically means partial and
>>>> specification typically means complete.
>>>>
>>>
>>> I don't think you'll find that most people will agree with this. That 
>>> might be your usage.
>>>
>>> The problem is that 'specification' has already been used in much of 
>>> this discussion to mean something else. A TM's specification outlines 
>>> what it is that that TM is supposed to do without going into the 
>>> details of how it actually does it.
>>>
>>
>> When you refer to the spec of an algorithm you
>> are correct. When you refer to the every single
>> step of the exact behavior that a finite string
>> specified you are wrong.
>>
>>> For example, the specification of a Parity Decider would be a TM 
>>> takes a representation of a natural number as its initial tape 
>>> content and accepts it only if it is even.
>>>
>>> The description of that machine, on the other hand, would describe 
>>> what the alphabet of this machine is, what it's state transitions 
>>> are, etc. i.e. it would give all the information necessary to 
>>> actually construct the machine.
>>>
>>> André
>>>
>>
>> I already know how TM machine descriptions actually work.
>>
>> DDD simulated by HHH1 has the exact same
>> sequence of steps as the directly executed DDD().
>>
>> People here think that when DDD is simulated by
>> the same simulator that it calls (thus causing
>> recursive simulation) that DDD must have the same
>> behavior as DDD simulated by HHH1 that DDD does
>> not call.
> 
> The behaviour of DDD is the behaviour that DDD specifies. If some
> program simulaates differently then it does not simulate the
> behaviour of DDD.
> 


It's not that hard really.
When an input calls its own simulator with itself as input
THIS DOES CHANGE ITS BEHAVIOR.

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