In this particular case it would still be infinite train proof people. But consider the infinite set of natural numbers. If the train killed only left handed people, you should still be left with infinite train proof right handed people. If, however you ran another train through the set that killed right handed people you would be left with no train proof people. In actual fact, though, the infinite set of “people killed by a train” is probably 100%.
While true, my point was that this is a thought experiment to show that subtracting infinite countable sets from infinite countable sets does not leave you necessarily with an infinite countable set.
In this particular case it would still be infinite train proof people. But consider the infinite set of natural numbers. If the train killed only left handed people, you should still be left with infinite train proof right handed people. If, however you ran another train through the set that killed right handed people you would be left with no train proof people. In actual fact, though, the infinite set of “people killed by a train” is probably 100%.
Well, infinite left-hand-killing-train proof people, we don’t know about other trains.
While true, my point was that this is a thought experiment to show that subtracting infinite countable sets from infinite countable sets does not leave you necessarily with an infinite countable set.