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:
“An empty book is like an infant’s soul, in which anything may be written. It is capable of all things, but containeth nothing. I have a mind to fill this with profitable wonders.”
—Thomas Traherne (1636–1674)
“He set the jug down slowly at his feet
With trembling care, knowing that most things break;”
—Edwin Arlington Robinson (1869–1935)