Can this set exists $\{\{\{\ldots\}\}\}$?
4213
The set that only contains itself
50258
How can a set contain itself?
93750
Can a set be neither open nor closed?
111032
Proof of Sets involving the Cartesian Product
158882
Prove the existence of some weird family of sets
109070
Question about the proof of the distributive property for sets
79568
Cardinality of the set $D$
42095
Existence in ZF of a set with countable power set
43024
Well-ordered sets, properties of an element that is not largest in the set
111723
Can it be proven in $\sf ZF^{\neg\infty}$ that the sets $x_n=\{x_{n+1}\}$ do not exist?
32441
How to prove or disprove statements about sets
47697
Russell's paradox: a set cannot contain its own powerset
146664
The union of two linearly independent subsets
130418
Is ${\{\emptyset,\{\emptyset\},\{\{\emptyset\}\},\{\{\{\emptyset\}\}\},...\}} $ a set?
151719
Connected set in $\mathbb{S}^1$
107564
If two sets have a natural (asymptotic) density, does their union?
92571
Sets with no asymptotical density over $\mathbb N$