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Anyone have any suggestions for a good write-up on Countability (from an intro to set theory perspective)?

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    Simply put, a set is countable if and only if it can be put into one-to-one correspondence with the natural numbers or a subset thereof. Now it is perhaps counterintuitive that the rationals are countable, but that can be proven (zig-zag pattern on table of rationals) easily enough.2016-04-19

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