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:
“Of all the diversions of life, there is none so proper to fill up its empty spaces as the reading of useful and entertaining authors.”
—Joseph Addison (1672–1719)
“Early, as well as late,
Rise with the sun, and set in the same bowers;”
—Henry Vaughan (1622–1695)