Does every set have a derangement?
37331
Prove that every set with more than one element has a permutation without fixed points
150825
Is an empty set equal to another empty set?
97951
Is the void set (∅) a proper subset of every set?
32441
How to prove or disprove statements about sets
110677
How is an empty set truly "empty"?
32296
Calling a space a set - abuse of terminology?
130418
Is ${\{\emptyset,\{\emptyset\},\{\{\emptyset\}\},\{\{\{\emptyset\}\}\},...\}} $ a set?
143828
Why does an conditionally convergent infinite series, when deranged, have a different limit?
92793
Can every set be written as a family?
74860
Why is the empty set a subset of every set?
106047
Does every element of tensor product look like this?
83706
Is there anything that is totally random?
82315
is an empty set an element of {empty set}
145781
Is the collection of all functions between two sets a set?
58594
Is the empty set a subset of itself?
149607
How to count derangements?
46698
Showing a set is closed under inverses