Schröder–Bernstein theorem for finite sets
121847
Don't we need the axiom of choice to choose from a non-empty set?
155190
Stone-Weierstrass theorem with $p(1/x)$
12436
The cardinality of the set of all finite subsets of an infinite set
137621
The Number of Topologies on a Finite Set
97064
Dense set in an infinite cofinite space
1409
Proving that the given set has at most $2^{n-1}$ elements
135112
Outer measure of product of sets
2882
Limit points of the set $\{\frac {\varphi(n) }n : n\in \mathbb{N}\}$
121097
Every not empty finite subset of a totally ordered set has a maximum and minimum
22558
Vitali-type set with given outer measure
147013
Subset of a finite set is finite
156176
Lebesgue measurability of nearly identical sets
37183
Show that the set of all $x$ such that $x \in P$ and $x \notin Q$ exists
33310
Proving that the set of limit points of a set is closed
82771
Proving that any polynomial $p:\mathbb{R}\rightarrow \mathbb{R}$ is not bounded, but its restriction to any bounded set is bounded
45792
Rigorous proof that surjectivity implies injectivity for finite sets
103717
Topological Property of the Set of Integers