A variant empty set symbol representing a collection containing no elements in set theory and logic.
Examples
Empty set notation in set theory
A \cap B = \varnothing
Set builder notation with empty result
\{x \in \mathbb{N} : x < 0\} = \varnothing
Set difference resulting in empty set
\{1, 2\} \setminus \{1, 2\} = \varnothing