How is the set of rational numbers countably infinite?
5803
Produce an explicit bijection between rationals and naturals?
87356
Are there any known uncountable transfinite increasing sequences of real numbers?
63276
Is an arbitrary union of a chain of countable sets countable?
81682
Proving the algebraic set corresponding to a polynomial is infinite.
15438
do all uncountable sets have same cardinality as real numbers?
9021
An infinite subset of a countable set is countable
75019
Infinite Cartesian product of countable sets is uncountable
85895
Proving all rational numbers including negatives are countable
102113
Proof that the number of proofs is countably infinite
60678
Does 'A countable infinite Cartesian product of countable sets is not necessarily countable' violate induction principle?
4518
How would one go about proving that the rationals are not the countable intersection of open sets?
100333
Show A is countable infinity
68430
Proving the countability of algebraic numbers
35692
The set of all finite subsets of the natural numbers is countable
119624
A Dedekind infinite set has a countably infinite proper subset
99478
countably infinite union of countably infinite sets is countable
31509
Is axiom of choice necessary for proving that every infinite set has a countably infinite subset?