On 5/26/2024 3:05 AM, Mikko wrote:
On 2024-05-25 11:42:59 +0000, olcott said:
On 5/25/2024 4:59 AM, Mikko wrote:
On 2024-05-24 16:57:36 +0000, olcott said:
On 5/24/2024 10:01 AM, Fred. Zwarts wrote:
Op 23.mei.2024 om 18:52 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 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.
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); 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.
The case can be simplified even more (D is not needed):
We are ONLY asking about whether D correctly simulated by pure function >>>>> H can possibly reach its own final state at line 06 and halt.
Because H is a pure function we know that H halts.
We don't know that H halts. The OP said the opposite:
The above references *pure function* H thus we do know
that the spec *requires* H to halt.
https://en.wikipedia.org/wiki/Pure_function
In that case the spec requires halting, though OP was not clar about that. >>
On 2024-05-23 16:52:21 +0000, olcott said:
*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.
Here OP is clear: H does not halt when both arguments are D.
Therefore H does not conform to the spec.
To repeat in endless recursve simulation makes halting impossible.
Apparently OP's interpretation of "pure function" does not imply
halting.
Every H is required to halt and return a value.
To make things simple every H returns the meaningless 56.
It is endless recursive simulation until H halts.
No, it isn't. "endless recursive simulation" means that H does not halt.
Thereis no "unless" in the OP.
I had to make the subject line of the thread a little less accurate
so that people could get the gist of what I was saying. Now I have
made it precise.
On 5/26/2024 11:04 AM, Mikko wrote:
On 2024-05-26 13:12:08 +0000, olcott said:
I had to make the subject line of the thread a little less accurate
so that people could get the gist of what I was saying. Now I have
made it precise.
Subject lines typically are as they are limited to one line. That's
not a problem.
*I finally have much better words*
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 we see that D correctly simulated by pure simulator H would remain
stuck in recursive simulation then we also know that D never reaches its
own line 06 and halts in less than an infinite number of correctly
simulated steps.
This means that D correctly simulated by pure function H also never
reaches it own line 06 and halts.
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