Re: Every D(D) simulated by H presents non-halting behavior to H ###

On 5/18/2024 3:54 AM, immibis wrote:

On 16/05/24 16:50, olcott wrote:

On 5/16/2024 5:48 AM, Mikko wrote:

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 }
 
Explaining how this is incorrect requires the prerequisite knowledge
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.
 
There are more steps beyond this mandatory prerequisite.