Is it possible to construct the transitive closure of a set without Infinity?
111723
Can it be proven in $\sf ZF^{\neg\infty}$ that the sets $x_n=\{x_{n+1}\}$ do not exist?
10477
Finding the closure of A=$\mathbb Q \cap [0,1]$.
30231
The boundary of union is the union of boundaries when the sets have disjoint closures
49374
Closure of a subset in a metric space
97373
Is whether a set is closed or not a local property?
46698
Showing a set is closed under inverses
65308
Axiom of Choice: Family of non-empty sets mutually disjoint or not?
19414
Uncountable subset with uncountable complement, without the Axiom of Choice
90826
Constructing a subset not in $\mathcal{B}(\mathbb{R})$ explicitly
68230
The cardinality of a countable union of sets with less than continuum cardinality
58447
Is axiom of choice required for there to be an infinite linearly independent set in a (non-finite-dimensional) vector space?
33117
Cyclic containment of sets
136755
Direct proof of empty set being subset of every set
63717
Is the closure of a set equal to the closure of the closure of that set?
120064
Proving that without the axiom of choice there is a set with an accumulation point that isn'tthe limit of a convergeant sequence
102048
Closure of a compact set in Regular space $ X $
5022
Can a set containing $0$ be purely imaginary?