The empty set as an Indexing set.
36881
Empty intersection and empty union
72440
Partition a set into $k$ non-empty subsets
16056
Is empty set element of every set if it is subset of every set?
109219
How do the sets $\emptyset\times B,\ A\ \times \emptyset, \ \emptyset \times \emptyset $ look like?
272
Cantor Sets/nonempty/cardinality
88205
How can I define a topology on the empty set?
84609
Unary intersection of the empty set
89506
Union of disjoint sets : Equivalence relations
110669
Linear span of the empty set
89712
For every set $A$, the empty set is a subset of $A$. The empty set is a set. Therefore, the empty set has a cardinality $\geq 1\ldots$
95373
Additive set function on a semiring of sets
3663
Finding counterexamples in elementary set theory.
51313
Extension of linearly independent set to a basis in an infinite dimensional vector space
6603
"Indexing" a vector
47697
Russell's paradox: a set cannot contain its own powerset
31212
The existence of the empty set is an axiom of ZFC or not?
30660
Empty set does not belong to empty set