Anyone have any suggestions for a good write-up on Countability (from an intro to set theory perspective)?
Looking for good online write-up on Countability (Set Theory)
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set-theory
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1I don't get the question. – 2012-09-20
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0@ Asaf - I'm helping out in an undergraduate course in Number Theory and am looking for a good introductory write-up on Countability to give to the students as background reading. Obviously related topics would include Countability of the Rationals, but it's really just for them to get a feel of what Countability (from a Set Theory perspective) is about. Thanks for asking me to clarify. – 2012-09-20
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1Are there any other possible perspectives? – 2012-09-20
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0Simply 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