Kuratowski closure-complementation problem

Kuratowski closure-complementation problem

[‚ku̇r·ə¦tȯf·skē ‚klō·zhər ‚käm·plə·men′tā·shən ‚präb·ləm] (mathematics) The problem of showing that at most 14 distinct sets can be obtained from a subset of a topological space by repeated operations of closure and complementation.