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:
“Beware the politically obsessed. They are often bright and interesting, but they have something missing in their natures; there is a hole, an empty place, and they use politics to fill it up. It leaves them somehow misshapen.”
—Peggy Noonan (b. 1950)
“The whole object of travel is not to set foot on foreign land; it is at last to set foot on one’s own country as a foreign land.”
—Gilbert Keith Chesterton (1874–1936)