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:
“to-morrow it seem
Like the empty words of a dream
Remembered on waking.”
—Robert Bridges (1844–1930)
“One does not set fire to a world which is already lost.”
—Friedrich Dürrenmatt (1921–1990)