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From: Richard Damon <richard@damon-family.org>
Newsgroups: comp.theory,sci.logic
Subject: Re: D correctly simulated by H cannot possibly halt --- templates and
 infinite sets
Date: Wed, 29 May 2024 07:31:39 -0400
Organization: i2pn2 (i2pn.org)
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On 5/28/24 11:49 PM, olcott wrote:
> On 5/28/2024 10:38 PM, Richard Damon wrote:
>> On 5/28/24 10:23 PM, olcott wrote:
>>> On 5/28/2024 9:04 PM, Richard Damon wrote:
>>>> On 5/28/24 12:16 PM, olcott wrote:
>>>>> typedef int (*ptr)();  // ptr is pointer to int function in C
>>>>> 00       int H(ptr p, ptr i);
>>>>> 01       int D(ptr p)
>>>>> 02       {
>>>>> 03         int Halt_Status = H(p, p);
>>>>> 04         if (Halt_Status)
>>>>> 05           HERE: goto HERE;
>>>>> 06         return Halt_Status;
>>>>> 07       }
>>>>> 08
>>>>> 09       int main()
>>>>> 10       {
>>>>> 11         H(D,D);
>>>>> 12         return 0;
>>>>> 13       }
>>>>>
>>>>> When Ĥ is applied to ⟨Ĥ⟩
>>>>> Ĥ.q0 ⟨Ĥ⟩ ⊢* embedded_H ⟨Ĥ⟩ ⟨Ĥ⟩ ⊢* Ĥ.qy ∞
>>>>> Ĥ.q0 ⟨Ĥ⟩ ⊢* embedded_H ⟨Ĥ⟩ ⟨Ĥ⟩ ⊢* Ĥ.qn
>>>>>
>>>>> *Formalizing the Linz Proof structure*
>>>>> ∃H  ∈ Turing_Machines
>>>>> ∀x  ∈ Turing_Machines_Descriptions
>>>>> ∀y  ∈ Finite_Strings
>>>>> such that H(x,y) = Halts(x,x)
>>>>
>>>> But since for x being the description of the H^ built from that H 
>>>> and y being the same, it turns out that no matter what answer H 
>>>> gives, it will be wrong.
>>>>
>>>
>>> We have not gotten to that point yet this post is so that
>>> you can fully understand what templates are and how they work.
>>
>> But note, x, being a Turing Machine, is NOT a "template"
>>
>> And H, isn't a "set of Turing Machines", but an arbitrary member of 
>> that set, so all we need to do is find a single x, y, possible 
>> determined as a function of H (so, BUILT from a template, but not a 
>> template themselves) that shows that particular H was wrong.
>>
>>
>> That is basically what Linz does.
>>
>> Given a SPECIFIC (but arbitary) H, we can construct a specific H^ 
>> built from a template from H, that that H can not get right.
>>
>> All the other H's might get this input right, but we don't care, we 
>> have shown that for every H we
>>
>>>
>>>> (And I think you have an error in your reference to Halts, I think 
>>>> you mean Halts(x,y) not Halts(x,x)
>>>>
>>>
>>> Yes good catch. I was trying to model embedded_H / ⟨Ĥ⟩
>>> and then changed my mind to make it more general.
>>>
>>>>>
>>>>> *Here is the same thing applied to H/D pairs*
>>>>> ∃H ∈ C_Functions
>>>>> ∀D ∈ x86_Machine_Code_of_C_Functions
>>>>> such that H(D,D) = Halts(D,D)
>>>>
>>>> Not the same thing.
>>>> ∃H ∈ C_Functions
>>>> is not equivalent to
>>>> ∃H  ∈ Turing_Machines
>>>>
>>>> as there are many C_Functions that are not the equivalent of Turing 
>>>> Machines.
>>>>
>>>
>>> The whole purpose here is to get you to understand what
>>> templates are and how they reference infinite sets.
>>>
>>
>> But the problem is that even in your formulation, H and D are, when 
>> doing the test, SPECIFIC PROGRAMS and not "templates" as Halts is 
>> defined on the domain of PROGRAMS.
>>
>> Similarly, a "Template" doesn't have a specific set of 
>> x86_Machine_Code_of_C_function, at least not one with defined behavior 
>> since if it tries to reference code outside of itself, then Halts of 
>> that just isn't defined, only Halts of that code + the specific 
>> machine deciding it.
>>
>>>>
>>>>>
>>>>> In both cases infinite sets are examined to see
>>>>> if any H exists with the required properties.
>>>>>
>>>>
>>>> Yes, but the logic of Turing Machines looks at them one at a time, 
>>>> and the input is a FULL INDEPENDENT PROGRAM.
>>>>
>>>
>>> ∃H  ∈ Turing_Machines
>>> That does not look at one machine it looks as an infinite set of
>>> machines. I am very happy to find out that you were not playing head
>>> games. Linz actually used the words that you referred to.
>>
>> while the ∃H part can create a set of machines, each element of that 
>> set is INDIVIDUALLY TESTED in the following conditions, so, when we 
>> get to your test  H(x,y) = Halts(x,x), each of H, x, y are individual 
>> members of the set, and we THEN collect the set of all of them.
>>
>> If we try to say
>> ∃x ∈ Natural Numbers, such that  x+x = 3
>> we can't say that x is both 1 and 2 and thus as a set meet the 
>> requirement. For the conditions, each qualifier select a single 
>> prospective element, and those are tested to see if that meet the 
>> requirement.
>>
> 
> So it never was about any specific machine as Linz misleading words
> seemed to indicate. It was always about examining each element of an
> infinite set.

No, you just don't understand how logic works.

The main body of the proof IS about a SPECIFIC (but arbitrary) machine 
out of the infinite set.

> 
> Likewise: ∃H ∈ C_Functions is about examining each element
> of an infinite set. A program template specifies a set of programs
> the same way that an axiom schema specifies a set of axioms.

Right EACH ELEMENT INDIVIDUALLY

> 
> I am very happy that the issue was the misleading words of Linz
> and not you playing head games.
> 

But you still don't seem to understand that the final statement

H(x,y) = Halts(x, y)

Is a statement about SPECIFIC Machines/inputs H, x, and y as individuals.

So, the evaluation of each term is done as an individual.

So, the question for THAT H, isn't can any machine in the do the 
simulation for its paired machine, it is did THIS H get the right answer 
for THIS input.

The fact that when H(D,D) says non-halting for the D built on it, but 
that D when used to process D(D) will halt, says that H just fails the 
requried test, so it CAN'T be an H that meets the requirements.

The fact that we can categorically do that for ALL Hs, that is find an 
x, y that they will get wrong, says the claim of the existance of an H 
that meets that requirement is a LIE.

You just don't understand how logic works, and think false statements 
can be true, becuase you just don't care about truth, but have a 
reckless disregard for it.