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:
“In the eighth, Hermanski smashed a drive to the scoreboard. Henrich backed against the board and leaped either four or fourteen feet into the air. He stayed aloft so long he looked like an empty uniform hanging in its locker. When he came down he had the ball.”
—Walter Wellesley (Red)
“O these encounterers, so glib of tongue,
That give a coasting welcome ere it comes,
And wide unclasp the tables of their thoughts
To every ticklish reader! Set them down
For sluttish spoils of opportunity
And daughters of the game.”
—William Shakespeare (1564–1616)