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:
“It was like taking a beloved person to the airport and returning to an empty house. I miss the people. I miss the world.”
—Susan Sontag (b. 1933)
“John Brown of Ossawattamie
Who died to set Abstraction free
Stole Washington’s gold-handled sword
Less for the gold than for the Lord....”
—Allen Tate (1899–1979)