Is the least inaccessible cardinal equivalent to the first aleph fixed point?
105594
Fixed point, union of $\aleph_0, \aleph_{\aleph_0},\aleph_{\aleph_{\aleph_0}}\dots$ [see Noah's comment on notation]
137203
Measurable cardinal existence condition
28452
Statement that is provable in $ZFC+CH$ yet unprovable in $ZFC+\lnot CH$
152382
Can an infinite set A be larger than an infinite set B but still have the same cardinality?
45216
Cardinality of $[0,1]$
92639
Prove that the family of open sets in $\mathbb{R}$ has cardinality equal to $2^{\aleph_0}$
35230
How to find fixed points for DES weak keys
118390
Symbol for the cardinality of the continuum
63489
The class of cardinal numbers is well ordered
79349
The Aleph numbers and infinity in calculus.
150605
Existence of a regular uncountable $\aleph_{\alpha}$ without $\mathsf{AC}$
126569
Can we find a well ordering on an infinite set with no largest element?
3217
Construction of uncountably many non-isomorphic linear (total) orderings of natural numbers
23442
Cardinality of the union of infinite and countable sets
68230
The cardinality of a countable union of sets with less than continuum cardinality
65768
What is the cardinality of the set of the empty set?
38242
Explicit bijection between the successor of $\alpha$ and $\alpha$ (infinite ordinal).