In ZFC, is it possible for a set to be an element of one of its elements?
14512
Why cannot a set be its own element?
122271
A subset of a transitive set is transitive
56370
Associative operation on a set $S$
156252
Are sets constructed using only ZF measurable using ZFC?
22498
In set theory, how are real numbers represented as sets?
18364
When does the set enter set theory?
7733
If A is infinite, does there have to exist a subset of A that is equivalent to A?
28452
Statement that is provable in $ZFC+CH$ yet unprovable in $ZFC+\lnot CH$
42603
How can I prove that the cadinality of a set minus a finite number of elements of it is still the same as the original set?
130771
Sets and the principle of inclusion and exclusion
152382
Can an infinite set A be larger than an infinite set B but still have the same cardinality?
144181
Given an arbitrary set $X$, can one always find an element outside $X$?
151521
Set Theory: Tree Property
63276
Is an arbitrary union of a chain of countable sets countable?
27025
How do I choose an element from a non-empty set?
102827
When do surjections split in ZF? Two surjections imply bijection?
97373
Is whether a set is closed or not a local property?