Is the set $A$ of anti-symmetric relations over $\mathbb{N}$ countable?
40937
Is the set of partial order relations over $ \mathbb{N}$ countable?
28539
Does any uncountable set contain two disjoint uncountable sets?
62687
Proving Cardinality of Cosets in Abstract Algebra
63276
Is an arbitrary union of a chain of countable sets countable?
103769
The Cartesian product of a finite number of countable sets is countable
150605
Existence of a regular uncountable $\aleph_{\alpha}$ without $\mathsf{AC}$
146436
Cardinality of the set of bijective functions on $\mathbb{N}$?
155168
Is the collection of finite subsets of $\mathbb{Z}$ countable?
52429
Explicit countable elementary extension of $\mathbb{N}$
128766
Show that the set of functions $\mathbb{N}\to\{0,1\}$ is not countable
35362
Number of equivalence relations on a set
142144
Countable or uncountable; family of disjoint triangles?
12459
Associativity of symmetric difference of sets
35692
The set of all finite subsets of the natural numbers is countable
13761
Automorphisms in $\mathbb{Z}_n$
41661
Show that the set of all finite subsets of $\mathbb{N}$ is countable.
124847
Is the set of surjective functions from $\mathbb{N}$ to $\mathbb{N}$ uncountable?