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From: olcott <polcott333@gmail.com>
Newsgroups: comp.theory
Subject: Re: How to write a self-referencial TM?
Date: Thu, 15 May 2025 15:50:34 -0500
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On 5/15/2025 2:57 PM, wij wrote:
> On Thu, 2025-05-15 at 11:47 -0500, olcott wrote:
>> On 5/15/2025 11:08 AM, Mike Terry wrote:
>>> On 14/05/2025 18:53, wij wrote:
>>>> On Wed, 2025-05-14 at 12:24 -0500, olcott wrote:
>>>>> On 5/14/2025 11:43 AM, wij wrote:
>>>>>> On Wed, 2025-05-14 at 09:51 -0500, olcott wrote:
>>>>>>> On 5/14/2025 12:13 AM, wij wrote:
>>>>>>>> Q: Write a turing machine that performs D function (which calls
>>>>>>>> itself):
>>>>>>>>
>>>>>>>> void D() {
>>>>>>>>      D();
>>>>>>>> }
>>>>>>>>
>>>>>>>> Easy?
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> That is not a TM.
>>>>>>
>>>>>> It is a C program that exists. Therefore, there must be a equivalent
>>>>>> TM.
>>>>>>
>>>>>>> To make a TM that references itself the closest
>>>>>>> thing is a UTM that simulates its own TM source-code.
>>>>>>
>>>>>> How does a UTM simulate its own TM source-code?
>>>>>>
>>>>>
>>>>> You run a UTM that has its own source-code on its tape.
>>>>
>>>> What is exactly the source-code on its tape?
>>>>
>>>
>>> Every UTM has some scheme which can be applied to a (TM & input tape)
>>> that is to be simulated.  The scheme says how to turn the (TM + input
>>> tape) into a string of symbols that represent that computation.
>>>
>>> So to answer your question, the "source-code on its tape" is the result
>>> of applying the UTM's particular scheme to the combination (UTM, input
>>> tape) that is to be simulated.
>>>
>>> If you're looking for the exact string symbols, obviously you would need
>>> to specify the exact UTM being used, because every UTM will have a
>>> different answer to your question.
>>>
>>>
>>> Mike.
>>>
>>
>> These things cannot be investigated in great
>> depth because there is no fully encoded UTM in
>> any standard language.
> 
> Sort of.
> 
>> If there was such a UTM then examining things
>> like a termination analyzer would be too difficult
>> because of the volume of details. Even moving a
>> single value to a specific memory location can
>> take many many steps.
> 
> So, which part of POOH is "fully encoded UTM"
> 
>> A RASP machine
>> https://en.wikipedia.org/wiki/Random-access_stored-program_machine
>> is a much better fit for examining the details of any
>> complex algorithm.
>>
>> The x86 language is essentially the same thing as a RASP
>> machine for all computations that can be accomplished
>> with the amount of memory that is available.
> 
> Absolutely false. POOH is the example that rejected TM/RASP instead of C.
> 
> In trying making P!=NP proof (may have defects, I just leave it there to improve)
> https://sourceforge.net/projects/cscall/files/MisFiles/PNP-proof-en.txt/download
> I feel TM would be very long and tedious, so I claimed that no *algorithm* can
> solve NPC (algorithmic) problems. (thanks to olcott, this proof was inspired in
> refuting POOH.)
> 
> See also Spu in my recent post. TM is very low-level to solve many idea of problems.
> 
>> To be a computable function within a model of computation
>> a sequence of the steps of a specific algorithm must be
>> applied to (an often finite string) input to derive an output.
>> https://en.wikipedia.org/wiki/Computable_function
>>
>> When computing the sum() function the steps of the algorithm
>> of arithmetic must be applied to the inputs.
>>
>> *When computing the halt() function steps with a simulating*
>> *termination analyzer the behavioral steps specified by the*
>> *input must be simulated according to the computer language*
>> *of this input*
>>
>> *I may be wrong yet it seems to me that*
>> Computer science never knew these things before in that
>> it never placed any limit on the type of algorithm that
>> must be performed.
>>
>> I think that it was Ben that said that one of two
>> functions that do nothing besides return true or false
>> is correct on all of the counter-example inputs
>> to the halting problem.
>>
>> When we require that a mapping be computed from an
>> input, then this idea is rejected.
>>
> 
> You are excellent in quoting tautology to support your claims.
> 

Most people don't know that a mapping must be
computed from the inputs, hence Ben's mistake.

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