Cardinality of the union of an ascending chain of sets
108957
Cardinality of a totally ordered union
91485
Finding an uncountable chain of subsets the integers
7785
Cardinality of sum-set
1627
Cartesian product of an arbitrary number of sets
32081
The dual version of trichotomy of cardinality without AC
67451
Building a bijection from a finite union of countable sets to $\mathbb{N}$
83518
Proving Two sets have same cardinality
111954
Computing the cardinality of a combinatorial set
24685
Expressing a Countable Union of Sets as the Countable Union of Disjoint Sets (e.g. Eliminating Duplicate Intersections)
82628
Cardinality of a set of closed intervals
5840
divides, not divides and cardinalities
7007
If $\alpha$ is a regular cardinal, the union of an elementary chain of $\alpha$-saturated models is also a $\alpha$-saturated model
150790
Prove two sets have same Cardinality by writing down bijection
153305
Adding subsets of regular cardinals (Jech p. 226)
132868
Bijection between an infinite set and its union of a countably infinite set
22232
Proving that cardinality of the reals = cardinality of $[0,1]$
86988
Cardinality of the Irrationals