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:
“And the empty pages?
Should they ever be filled
Let it be with observed
Celestial recurrences....”
—Philip Larkin (1922–1986)
“Alas, poor Yorick! I knew him, Horatio: a fellow of infinite jest, of most excellent fancy.... Where be your jibes now, your gambols, your songs, your flashes of merriment that were wont to set the table on a roar?”
—William Shakespeare (1564–1616)