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:
“Come hither, all ye empty things,
Ye bubbles rais’d by breath of Kings;
Who float upon the tide of state,
Come hither, and behold your fate.
Let pride be taught by this rebuke,
How very mean a thing’s a Duke;
From all his ill-got honours flung,
Turn’d to that dirt from whence he sprung.”
—Jonathan Swift (1667–1745)
“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)