> Apparently there's something wrong with backward supertasks (and not > with ordinary, 'forward' supertasks). But why should that be?
Well, I'm not at all sure that there's no problem with forward supertasks. Surely, it is not difficult to come up with a problematic case.
For instance, take our favorite example: at each time t - 1/n, place balls 10(n-1) to 10n - 1 in a vase and then remove ball n. At the end the vase is empty.
Now alter the situation slightly. At each step, again place 10 balls into the vase and then remove one ball, but remove the ball *randomly*. At the end, the vase may contain any number of balls. This strikes me as suitably counterintuitive to say that the forward supertask has something wrong with it. Or, perhaps, with my intuitions.
-- "To solve this problem, we define a security flag, known as the 'evil' bit, in the IPv4 [RFC791] header. Benign packets have this bit set to 0; those that are used for an attack will have the bit set to 1." -- RFC 3514