Empty Set

A set containing no elements, denoted as $\varnothing$ or $\{\}$. The empty set is a subset of every set.

Context

The empty set is a foundational concept in set theory. For example, the set of all integers that are both even and odd is $\varnothing$. The power set of the empty set is $\{\varnothing \}$, which has cardinality 1.

See Also

• set
• subset
• cardinality
• complement
• universal set
• empty language