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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: D(D) simulated by H cannot possibly reach past its own line 03
Date: Thu, 6 Jun 2024 11:07:54 +0300
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On 2024-06-05 13:05:11 +0000, olcott said:

> On 6/5/2024 2:05 AM, Mikko wrote:
>> On 2024-06-03 18:09:30 +0000, olcott said:
>> 
>>> On 6/3/2024 9:17 AM, Mikko wrote:
>>>> On 2024-06-03 12:25:48 +0000, olcott said:
>>>> 
>>>>> On 6/3/2024 2:39 AM, Mikko wrote:
>>>>>> On 2024-06-02 14:50:26 +0000, olcott said:
>>>>>> 
>>>>>>> On 6/2/2024 4:50 AM, Fred. Zwarts wrote:
>>>>>>>> Op 03.mei.2024 om 15:40 schreef olcott:
>>>>>>>>> 00 int H(ptr x, ptr x)  // ptr is pointer to int function
>>>>>>>>> 01 int D(ptr x)
>>>>>>>>> 02 {
>>>>>>>>> 03   int Halt_Status = H(x, x);
>>>>>>>>> 04   if (Halt_Status)
>>>>>>>>> 05     HERE: goto HERE;
>>>>>>>>> 06   return Halt_Status;
>>>>>>>>> 07 }
>>>>>>>>> 08
>>>>>>>>> 09 void main()
>>>>>>>>> 10 {
>>>>>>>>> 11   H(D,D);
>>>>>>>>> 12 }
>>>>>>>>> 
>>>>>>>>> We are examining the behavior of D(D) for every possible H/D pair
>>>>>>>>> where 1 to N steps of D(D) are simulated by H.
>>>>>>>>> 
>>>>>>>>> *Execution Trace*
>>>>>>>>> Line 11: main() invokes H(D,D) that simulates D(D)
>>>>>>>>> 
>>>>>>>>> *keeps repeating* (unless aborted)
>>>>>>>>> Line 01
>>>>>>>>> Line 02
>>>>>>>>> Line 03: simulated D(D) invokes simulated H(D,D) that simulates D(D)
>>>>>>>>> 
>>>>>>>>> *Simulation invariant*
>>>>>>>>> D correctly simulated by H cannot possibly reach past its own line 03.
>>>>>>>> 
>>>>>>>> The Linz proof is based on the pathological relation ship that D 
>>>>>>>> contradicts the result of H. This is expressed in lines 04, 05, 06 of 
>>>>>>>> D, above.
>>>>>>>> It is strange that olcott claims that the simulation never sees the 
>>>>>>>> pathological part of D. He now seems to shift the meaning of 
>>>>>>>> pathological to the mere fact that D calls H. Lines 04, 05, and 06 are 
>>>>>>>> completely irrelevant.
>>>>>>>> In fact, any function that calls H now become pathological.
>>>>>>>> 
>>>>>>>> E.G. if we replace D with a function P that only returns its own Halt_Status:
>>>>>>>> 
>>>>>>>> 01 int P(ptr x)
>>>>>>>> 02 {
>>>>>>>> 03   int Halt_Status = H(x, x);
>>>>>>>> 04
>>>>>>>> 05
>>>>>>>> 06   return Halt_Status;
>>>>>>>> 07 }
>>>>>>>> 
>>>>>>>> Then we would normally expect that, because H is required to halt, P 
>>>>>>>> would halt as well. But the simulation of P by H does not halt. So, P, 
>>>>>>>> when it halts, reports that it not halting.
>>>>>>>> 
>>>>>>>> The problem here is, that H is unable to simulate itself to its final 
>>>>>>>> state. That has no relation with the Linz proof, it is a problem of H.
>>>>>>>> 
>>>>>>>> So, there is another *Simulation invariant*
>>>>>>>> H correctly simulated by H cannot possibly reach its own return.
>>>>>>>> 
>>>>>>> 
>>>>>>> Already addressed in another reply.
>>>>>> 
>>>>>> Which reply? The one where you said you made a mistake? Or typo?
>>>>>> 
>>>>> 
>>>>> I am not going to answer the same question from multiple people.
>>>> 
>>>> Your choice. But you can't keep multiple people from seeing your
>>>> lack of answer.
>>>> 
>>> 
>>> This is my canned reply that no one has attempted to refute because
>>> they know it is irrefutable. When we are analyzing x86 code and
>>> someone disagrees that is like disagreeing that 2 + 3 = 5.
>> 
>> The code has been anylzed by several people so carefully that
>> any disagreement really is like s like disagreeing that 2 + 3 = 5.
>> But you disagree anyway:
>> 
> 
> It has been "analyzed" by dogmatic assertions utterly bereft
> of any supporting reasoning.

So it has, at least by you.

> It is empirically proven that the behavior of the directly executed
> DD(DD) is different than the behavior of DD correctly simulated by
> HH.

Empirical observations are not an analysis. They do not prove about
the same as an analysis so cannot contradict. Any demonstration of
any relation between the two requires a careful comparison the details
of each, for example whether the HH in the empirical proof is similar
enough to H in the analysis.

> People can lie about this yet cannot possibly show otherwise.

That is the restriction of some people, for example you. But some have
shown otherwise. They needn't to show it to you but for someone not yet
familiar with the topic those demonstrations can be useful.

-- 
Mikko