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On 29/04/2025 20:06, olcott wrote:THE CODE THAT IT CAN SEEOn 4/29/2025 8:46 AM, Richard Heathfield wrote:Yes, it can. There is no need to see the behaviour to establish whether it halts. All the decider has to be able to see is the code.On 29/04/2025 14:11, olcott wrote:>On 4/29/2025 2:10 AM, Richard Heathfield wrote:>On 29/04/2025 03:50, olcott wrote:
<snip>
>>>Yet it is H(P,D) and NOT P(D) that must be measured.>
Nothing /has/ to be measured. P's behaviour (halts, doesn't halt) when given D as input must be /established/.
No H can possibly see the behavior of P(D)
It doesn't have to.
IF IT CAN'T SEE IT THEN IT CAN'T REPORT ON IT.
I, as a decider, do not need to see the following program's behaviour to determine whether it halts...IT DOES NOT WORK THAT WAY WITH PATHOLOGICAL SELF-REFERENCE.
int main(void)
{
while(1);
return 0;
}
...because I can tell just by reading the code that it enters an infinite loop and so will not halt. I can report on whether the program halts without having to execute it.
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