Kuratowski's closure-complement problem

At most 14 distinct sets can be obtained by repeatedly applying the set operations of closure and complement to a given seed set in a topological space. This result was first published by Kazimierz Kuratowski in 1922. Many variations have appeared since, especially after 1960.

References

1. Kelley, J. L. General Topology. Princeton: Van Nostrand, p. 57, 1955.

2. Kuratowski, K. Sur l'operation A de l'analysis situs. Fund. Math. 3, 182-199, 1922.

External links

• The Kuratowski Closure-Complement Problem by B.J. Gardner and Marcel Jackson

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