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:
“Fact I know; and Law I know; but what is this Necessity, save an empty shadow of my own mind’s throwing?”
—Thomas Henry Huxley (1825–95)
“It may be that the most interesting American struggle is the struggle to set oneself free from the limits one is born to, and then to learn something of the value of those limits.”
—Greil Marcus (b. 1945)