Re: D correctly simulated by H cannot possibly reach its own line 06 and halt

On 5/31/2024 2:50 AM, Fred. Zwarts wrote:

Op 31.mei.2024 om 00:01 schreef olcott:

On 5/30/2024 4:54 PM, joes wrote:

Am Thu, 30 May 2024 09:55:24 -0500 schrieb 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 left hand-side are line numbers of correct C code.
This code does compile and does conform to c17.
>
Everyone with sufficient knowledge of C can easily determine that D
correctly emulated by any *pure function* H (using an x86 emulator)
cannot possibly reach its own simulated final state at line 06 and halt.

Yeah, of course not, if H doesn’t halt.
>

>
To actually understand my words (as in an actual honest dialogue)
you must pay careful attention to every single word. Maybe you
had no idea that *pure functions* must always halt.
>
Or maybe you did not know that every computation that never reaches
its own final state *DOES NOT HALT* even if it stops running because
it is no longer simulated.

>
Since the claim is that H is also a computation, it holds for H, as well. That means that H *DOES NOT HALT* even if it stops running because it is no longer simulated.
 

*pure function H definitely halts you are confused*
I stop at your first big mistake so that we can resolve this key
mistake before moving on.
"...the Turing machine will halt whenever it enters a final state."
Linz(1990:234)
In computer programming, a pure function is a function that has the
following properties:
(1) the function return values are identical for identical arguments
(no variation with local static variables, non-local variables, mutable
reference arguments or input streams), and
(2) the function has no side effects (no mutation of local static
variables, non-local variables, mutable reference arguments or
input/output streams). https://en.wikipedia.org/wiki/Pure_function
DD correctly simulated by pure function HH cannot possibly reach
its own final state at line 06 in any finite number of steps of
correct simulation.
Pure function H reaches its own final state after the finite number
of steps of correct simulation, thus halts.
Linz, Peter 1990. *An Introduction to Formal Languages and Automata*
Lexington/Toronto: D. C. Heath and Company. (317-320)
--
Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius
hits a target no one else can see." Arthur Schopenhauer