In mathematics, and more specifically set theory, the empty set is the unique set having no elements; its size or cardinality (count of elements in a set) is zero. Some axiomatic set theories assure that the empty set exists by including an axiom of empty set; in other theories, its existence can be deduced. Many possible properties of sets are trivially true for the empty set.
Null set was once a common synonym for "empty set", but is now a technical term in measure theory.
Read more about Empty Set: Notation, Properties
Famous quotes containing the words empty and/or set:
“In vain we lavish out our lives,
To gather empty wind;
The choicest blessings earth can yield
Will starve a hungry mind.”
—Isaac Watts (1674–1748)
“What shall we say who have knowledge
Carried to the heart? Shall we take the act
To the grave? Shall we, more hopeful, set up the grave
In the house? The ravenous grave?”
—Allen Tate (1899–1979)