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:
“January, month of empty pockets!... Let us endure this evil month, anxious as a theatrical producer’s forehead.”
—Colette [Sidonie Gabrielle Colette] (1873–1954)
“Whoever wants to set a good example must add a grain of foolishness to his virtue: then others can imitate and yet at the same time surpass the one they imitate—which human beings love to do.”
—Friedrich Nietzsche (1844–1900)