Does the empty set count as an element?
65768
What is the cardinality of the set of the empty set?
109219
How do the sets $\emptyset\times B,\ A\ \times \emptyset, \ \emptyset \times \emptyset $ look like?
27025
How do I choose an element from a non-empty set?
9434
How do I check if a list is empty?
8937
How do I reference the only element in a singleton set?
114378
How to check if the string is empty?
125957
What is the product of the empty set?
7443
Why is empty product defined to be $1$?
58594
Is the empty set a subset of itself?
33064
Powerset of set with empty sets
23586
What is the difference between String.Empty and "" (empty string)?
30660
Empty set does not belong to empty set
68244
Is ∅ equivalent to {∅}?
73021
Javascript : is given function empty?
124325
Element of, subset of and empty sets
56637
In naive set theory ∅ = {∅} = {{∅}}?
49616
Why does NOT IN with a set containing NULL always return FALSE/NULL?