Re: Overcoming the proof of undecidability of the Halting Problem by a simple example in C

On 19/05/2025 01:33, olcott wrote:

On 5/18/2025 7:27 PM, Ben Bacarisse wrote:

Richard Heathfield <rjh@cpax.org.uk> writes:

 [Apologies for not snipping. This one was hard to know how best to edit down.]
 

>

On 18/05/2025 23:18, Ben Bacarisse wrote:

Richard Heathfield <rjh@cpax.org.uk> writes:
...

If they know C they should know that it's
   u32 HHH(void (*P)()), according to Halt7.c.
>
It takes a pointer to a function that accepts no arguments and returns no
value.

Yes, but I am surprised that you are being so modern!!  You used to
favour C90 and didn't really care for anything more recent.

>
I am just as surprised that you missed the distinction I was making, which
was between these:
>
void HHH(void (*f)(void))
u32 HHH(void (*P)())
>
Empty parentheses had nothing to do with my point. On line 16 we find:
typedef uint32_t u32;
>
uint32_t != void.

>
Yes, I got the distinction you were making, but I must have got confused
about the referent of "it" in the part I quoted.  I was hoping to add
to the discussion despite ignoring your main point.  Sorry.
>

>
*Copied from the original post that he responded to*
>
int DD()
  {
   int Halt_Status = HHH(DD);
   if (Halt_Status)
     HERE: goto HERE;
   return Halt_Status;
  }

 Not so. The post I responded to was Message-ID: <1009lm9$b15q$1@dont- email.me>
 There was a lot of quoted material, none of which mentioned int DD(), although it did mention a void DDD().
 The only original material was:
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
No, there are peole who do know C but don't know that HHH is not
void HHH(void (*f)(void)) {} and how therefore cannot tell that
HHH does simulate DDD.