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:
“Fat black bucks in a wine-barrel room,
Barrel-house kings, with feet unstable,
Sagged and reeled and pounded on the table,
Pounded on the table,
Beat an empty barrel with the handle of a broom,
Hard as they were able,”
—Vachel Lindsay (1879–1931)
“The people always have some champion whom they set over them and nurse into greatness.... This and no other is the root from which a tyrant springs; when he first appears he is a protector.”
—Plato (c. 427–347 B.C.)