Are Infinite ordinals and their successor equinumerous?
38242
Explicit bijection between the successor of $\alpha$ and $\alpha$ (infinite ordinal).
23442
Cardinality of the union of infinite and countable sets
149277
Does well-ordering of the proper class of cardinal numbers imply choice?
59385
Are there number systems corresponding to higher cardinalities than the real numbers?
99478
countably infinite union of countably infinite sets is countable
60678
Does 'A countable infinite Cartesian product of countable sets is not necessarily countable' violate induction principle?
45878
Elementary Set Theory: Ordinals, Well Orderings and Isomorphisms
53525
Infiniteness of non-twin primes.
146560
Is there any uncountably infinite set that does not generate the reals?
24582
Is the set of sequences of natural numbers with trailing zeros countable?
118849
If a cyclic group has an element of infinite order, how many elements of finite order does it have?
86926
Why isn't this a well ordering of $\{A\subseteq\mathbb N\mid A\text{ is infinite}\}$?
86154
Why is this true? A set is Dedekind infinite if and only if equipotent to the union with the set containing itself
34387
Is the number of irreducibles in any number field infinite?
16971
Prove that no ordinal is an element of itself
104190
Can any infinite ordinal be expressed as the sum of a limit ordinal and a finite ordinal?
48278
Inequality about infinite cardinals