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From: olcott <polcott333@gmail.com>
Newsgroups: comp.theory,sci.logic
Subject: Re: Can you see that D correctly simulated by H remains stuck in
 recursive simulation?
Date: Fri, 24 May 2024 12:10:04 -0500
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On 5/24/2024 2:37 AM, Fred. Zwarts wrote:
> Op 23.mei.2024 om 19:04 schreef olcott:
>> 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       }
>>
>> The above template refers to an infinite set of H/D pairs where D is
>> correctly simulated by pure function H. This was done because many
>> reviewers used the shell game ploy to endlessly switch which H/D pair
>> was being referred to.
>>
>> *Correct Simulation Defined*
>>     This is provided because every reviewer had a different notion of
>>     correct simulation that diverges from this notion.
>>
>>     A simulator is an x86 emulator that correctly emulates at least one
>>     of the x86 instructions of D in the order specified by the x86
>>     instructions of D.
>>
>>     This may include correctly emulating the x86 instructions of H in
>>     the order specified by the x86 instructions of H thus calling H(D,D)
>>     in recursive simulation.
>>
>> *Execution Trace*
>>     Line 11: main() invokes H(D,D); H(D,D) simulates lines 01, 02, and 03
>>     of D. This invokes H(D,D) again to repeat the process in endless
>>     recursive simulation.
>>
> 
> Of course this depends very much on the exact meaning of 'correct 
> simulation', or 'correctly emulating'. 

Not when these are defined above.

> E.g., take the call to H(p, p). 
> If H recognizes that it is a call to a H with the same algorithm as is 
> it using itself, and it knows that itself returns a certain integer 
> value K, than it can be argued that it is a correct emulation to 
> substitute the call to H with this integer value K, which is assigned to 
> Halt_Status. Then the simulation of D can proceed to line 04.
> What we need is an exact definition of 'correct simulation', in this 

No, you simply need to pay complete attention to the fact that this
has already been provided.

I have been over the exact same issue with dozens and dozen of people
though hundreds and hundreds of messages over two years.

> case for the call instruction. Is it allowed to make assumptions for the 
> result of a call, or is a call only correctly emulated by simulating the 
> instructions of the called function?

-- 
Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius
hits a target no one else can see." Arthur Schopenhauer