Why is $\aleph_0$ the smallest cardinal number?
60004
Why is $\omega$ the smallest $\infty$?
86902
Consider the smallest number in each of the $n\choose r$ subsets (of size $r$) of $S=\{1,2,\ldots,n\}$...
27889
If the set of odd numbers is a subset of $\mathbb N$ then surely it is smaller than $\mathbb N$
98163
Question regarding exponentiation of cardinal numbers
74281
Proof there is no largest cardinal number
76240
How is $\epsilon_0$ countable?
81509
The cardinality of a countable union of countable sets, without the axiom of choice
132298
How do you find the smallest of homeomorphic ordinals?
30519
"Real" cardinality, say, $\aleph_\pi$?
4782
Can we distinguish $\aleph_0$ from $\aleph_1$ in Nature?
32081
The dual version of trichotomy of cardinality without AC
93330
Cardinality of all cardinalities
3902
Does $k+\aleph_0=\mathfrak{c}$ imply $k=\mathfrak{c}$ without the Axiom of Choice?
136069
Is there a simple formula for the cardinality of $\{A\subseteq\kappa\mid |A|\leq\lambda\}$ when $\lambda\leq\kappa$?
133481
How to find the smallest number with just $0$ and $1$ which is divided by a given number?
45218
Comparing the two cardinals $\aleph_0^{\aleph_0}$ and $2^{\aleph_0}$
38764
bound on the cardinality of the continuum? I hope not