In topology and related branches of mathematics, the Kuratowski closure axioms are a set of axioms that can be used to define a topological structure on a set. They are equivalent to the more commonly used open set definition. They were first formalized by Kazimierz Kuratowski,[1] and the idea was further studied by mathematicians such as Wacław Sierpiński and António Monteiro,[2] among others.
A similar set of axioms can be used to define a topological structure using only the dual notion of interior operator.[3]