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:
“The sole work and deed of universal freedom is therefore death, a death too which has no inner significance or filling, for what is negated is the empty point of the absolutely free self. It is thus the coldest and meanest of all deaths, with no more significance than cutting off a head of cabbage or swallowing a mouthful of water.”
—Georg Wilhelm Friedrich Hegel (1770–1831)
“I have heard, in such a way as to believe it, of your recently saying that both the Army and the Government needed a Dictator. Of course it was not for this, but in spite of it, that I have given you the command. Only those generals who gain success, can set up dictators.”
—Abraham Lincoln (1809–1865)