Kuratowski's Closure-Complement Problem

Let X be an arbitrary topological space. Denote the set closure of a subset A of X by A^- and the complement of A by A^'. Then at most 14 different sets can be derived from A by repeated application of closure and complementation (Berman and Jordan 1975, Fife 1991). The problem was first proved by Kuratowski (1922) and popularized by Kelley (1955).

See also

Complement Set, Kuratowski Reduction Theorem, Set Closure, Subset

Portions of this entry contributed by Mark Bowron

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Kuratowski's Closure-Complement Problem

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Bowron, Mark and Weisstein, Eric W. "Kuratowski's Closure-Complement Problem." From MathWorld--A Wolfram Web Resource.

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