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:
“Poetry
Exceeding music must take the place
Of empty heaven and its hymns....”
—Wallace Stevens (1879–1955)
“A fool, A fool! I met a fool i’ the forest,
A motley fool. A miserable world!
As I do live by food, I met a fool,
Who laid him down and basked him in the sun,
And railed on Lady Fortune in good terms,
In good set terms, and yet a motley fool.”
—William Shakespeare (1564–1616)