Kuratowski's closure-complement problem
Sign in to savetheorem that the monoid generated by taking closures and complements of a given set in a topological space has size at most 14, attained by e.g. the set (0, 1) ∪ (1, 2) ∪ {3} ∪ ([4, 5] ∩ ℚ) of reals
Connections
algebra
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International Standard Book Number
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real number
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topology
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Wayback Machine
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digital object identifier
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International Standard Serial Number
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interval
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Q118398
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topological space
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function composition
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complement
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monoid
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semigroup
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Kazimierz Kuratowski
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Q22908627
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involution
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general topology
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idempotence
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interior
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