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From: olcott <polcott333@gmail.com>
Newsgroups: comp.lang.c,comp.lang.c++
Subject: Re: Can someone please verify the execution trace of this?
Date: Mon, 20 May 2024 00:38:47 -0500
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On 5/20/2024 12:09 AM, Bonita Montero wrote:
> Am 20.05.2024 um 04:43 schrieb olcott:
>> On 5/19/2024 8:52 PM, Bonita Montero wrote:
>>> Am 19.05.2024 um 21:00 schrieb olcott:
>>>> On 5/19/2024 1:08 PM, Bonita Montero wrote:
>>>>> Am 18.05.2024 um 23:40 schrieb olcott:
>>>>>> People are saying that they have no idea what this code does
>>>>>> because they do not believe it conforms to c11 or c17.
>>>>>>
>>>>>> typedef int (*ptr)();  // ptr is pointer to int function
>>>>>> 00 int H(ptr x, ptr y);
>>>>>> 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 int main()
>>>>>> 10 {
>>>>>> 11   H(D,D);
>>>>>> 12   return 0;
>>>>>> 13 }
>>>>>>
>>>>>> In the above case 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);
>>>>>>
>>>>>> *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 key thing to note is that no D correctly simulated by any H of 
>>>>>> every
>>>>>> H/D pair specified by the above template ever reaches its own line 06
>>>>>> and halts.
>>>>>>
>>>>>
>>>>> Other people think 30s about this, you think years about that.
>>>>>
>>>>
>>>> It is the basis for my two decades long primary research into 
>>>> termination analysis. People on another forum have written
>>>> hundreds of posts claiming that D correctly simulated by H
>>>> reaches its own line 06 and halts.
>>>>
>>>> *I have only gotten truthful answers on this forum*
>>>>
>>>
>>> That's not research, that's nonsense.
>>>
>>
>> This is not the forum to show that it is not nonsense this is
>> a simple C question that I should not even have to ask except
>> for a few people in another forum that consistently lie about
>> the answer.
>>
>> I have been a professional C++ developer since Y2K. So I already
>> know the answer, I just need some competent people in this forum
>> to attest to this answer. I met Bjarne Stroustrup back when he
>> was going around the country promoting his new language.
>>
> 
> You ask the same questions over and over again for years.
> It's like circling your thoughts before you fall asleep -
> you don't think about whether it really makes sense.
> 

It would take three people five minutes a piece.
Then I can go back to the other forum.

They have been lying about how the above code works
consistently for two years. I know how it works. I
learned C back when K & R was the standard.

Three people take five minutes a piece to confirm the
that the last sentence is correct.

typedef int (*ptr)();  // ptr is pointer to int function
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 }

In the above case 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);

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.

H must be a pure function
https://en.wikipedia.org/wiki/Pure_function#

*THIS ONE SENTENCE NEEDS TO BE CONFIRMED*
For every H/D pair of the above template D correctly simulated
by H cannot possibly reach its own final state at line 06 and halt.


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