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 angels yawning in an empty heaven;
Alternate shows of dynamite and rain;
And choosing forced on free will: fire or ice.”
—Philip Larkin (1922–1986)
“I must have the gentleman to haul and draw with the mariner, and the mariner with the gentleman ... I would know him, that would refuse to set his hand to a rope, but I know there is not any such here.”
—Francis, Sir Drake (1540–1596)