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:
“I have heard the pigeons of the Seven Woods
Make their faint thunder, and the garden bees
Hum in the lime-tree flowers; and put away
The unavailing outcries and the old bitterness
That empty the heart.”
—William Butler Yeats (1865–1939)
“A wise man should order his interests, and set them all in their proper places. This order is often troubled by greed, which puts us upon pursuing so many things at once that, in eagerness for matters of less consideration, we grasp at trifles, and let go things of greater value.”
—François, Duc De La Rochefoucauld (1613–1680)