Kuratowski's closure-complement problem
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In the mathematical subject of topology, Kuratowski's closure-complement problem refers to the statement that at most 14 distinct sets can be obtained by repeatedly applying the set operations of closure and complement to a given starting subset of a topological space. This result was first published by Kazimierz Kuratowski in 1922. Many variations have appeared since, especially after 1960.
A subset realizing the maximum of 14 is called a 14-set. The real numbers have subsets that are 14-sets.
[edit] 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.
[edit] External links
- The Kuratowski Closure-Complement Problem by B.J. Gardner and Marcel Jackson