True or false: Are algebraic numbers countable?
You can't use axiom of choice.
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Anonymous2009-09-22 23:25
>>7
Dumbass. If X is a countable set whose members are all countable sets, theres a clear bijection between NxN and UX. NxN is countable by a diagonalization argument, does not require AC at all. Are you suggesting that the rationals cannot be proved countable if you assume the negation of AC?