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From: Richard Damon <richard@damon-family.org>
Newsgroups: comp.theory,sci.logic
Subject: Re: My reviewers think that halt deciders must report on the behavior
 of their caller
Date: Sat, 12 Jul 2025 08:20:28 -0400
Organization: i2pn2 (i2pn.org)
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On 7/12/25 7:53 AM, Mr Flibble wrote:
> On Sat, 12 Jul 2025 10:17:55 +0200, Fred. Zwarts wrote:
> 
>> Op 11.jul.2025 om 23:05 schreef olcott:
>>> On 7/11/2025 3:52 AM, Fred. Zwarts wrote:
>>>> Op 10.jul.2025 om 16:35 schreef olcott:
>>>>> On 7/10/2025 5:54 AM, Fred. Zwarts wrote:
>>>>>> Op 09.jul.2025 om 15:02 schreef olcott:>
>>>>>>> All Turing machine deciders only compute the mapping from their
>>>>>>> actual inputs. This entails that they never compute any mapping
>>>>>>> from non-inputs.
>>>>>>
>>>>>> At least one thing you understand.
>>>>>>
>>>>>>
>>>>> *From the bottom of page 319 has been adapted to this*
>>>>> https://www.liarparadox.org/Peter_Linz_HP_317-320.pdf
>>>>>
>>>>> *The Linz proof does not understand this*
>>>>>
>>>>> When Ĥ is applied to ⟨Ĥ⟩
>>>>> Ĥ.q0 ⟨Ĥ⟩ ⊢* Ĥ.embedded_H ⟨Ĥ⟩ ⟨Ĥ⟩ ⊢* Ĥ.∞
>>>>>     *if Ĥ applied to ⟨Ĥ⟩ halts, and*
>>>>> Ĥ.q0 ⟨Ĥ⟩ ⊢* Ĥ.embedded_H ⟨Ĥ⟩ ⟨Ĥ⟩ ⊢* Ĥ.qn
>>>>>     *if Ĥ applied to ⟨Ĥ⟩ does not halt*
>>>>>
>>>>>
>>>>>
>>>>>>>> The evidence is that the input includes the code to abort and
>>>>>>>> halt,
>>>>>>>
>>>>>>> abort and stop running *IS NOT THE SAME THING AS*
>>>>>>> abort and halt
>>>>>>
>>>>>> Another claim without evidence.
>>>>>>
>>>>>>
>>>>> *It is common knowledge in the theory of computation*
>>>>>
>>>>>
>>>> Another claim without evidence.
>>>>
>>>>
>>> *Your lack of knowledge of computer science is not a rebuttal*
>>>
>>> Look at the definition of a Turing Machine (e.g., the one here). The
>>> machine has states. Each state can be final or non-final. If the
>>> machine's state is non-final, in the next step the machine "does"
>>> something, namely, it can write something on the tape, move its head,
>>> and/or change its state to a different state. This is how the machine
>>> makes a progress.
>>
>> So, aborting the simulation when the machine has not yet reached its
>> final state, is a violation of the Turing Machine.
> 
> Nonsense, if that was true static code analysers wouldn't be a thing.
> 
> /Flibble

Sure it could be. Note the difference between RUNNING a program and 
ANALYSIZING a program.

The ONLY thing that actually determines the behavior of a Turing Machine 
is its behavior when actually run, and that behavior NEVER stops until 
it reaches a final state, and thus any simulation that stops before 
then, does not, in itself, define that behavior.

It is possible, in some cases, to be able from a partial simulation, 
actually prove what the complete execution of that program would be, and 
that is something that  static code analyser would try to do. The key 
here is static code analysing is not 100% determinative. Some programs 
it can determine WILL halt. Some program it can determine will NEVER 
halt. But there are always some programs that it can not determine the 
correct answer. It isn't that the program doesn't have a correct answer, 
just that the analyser isn't "smart" enough to determine it.