> I believe the real axiom is that a process cannot determine itself.
Alan Turing proved that it is impossible to write a program that can scan
any other program and determine, in a finite amount of time, whether or not
the second program will ever halt.
> For example. I am a progem. You write an infinite loop. I determine that
> it will be infinite. I've just
> predicted your program.
I'm not sure what exactly you mean here, but consider this: One of the great
unsolved math questions is whether or not there exists an odd perfect number
(see www.primepuzzles.net/conjectures/conj_011.htm). It is trivial to write
a function which takes a number and determines whether or not it is
perfect. Let's call that is_perfect().
Now, here's a program:
void
my_func (void) {
int i = 1;
while (!is_perfect (i))
i += 2;
}
Does this program halt? (Neglect the fact that after about 2^30 iterations,
the int will overflow) If you can positively answer yes or no, you'll have
solved a problem that has stumped mathematicians since Euclid.
--
Mike Schiraldi
Verisign Applied Research
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