I crossed with the Kuratowski closure-complement theorem while learning Munkres's Topology (Problem 21 in Section 17; Page 102, 2nd edition). The following description is from B.J. Gardner and M. Jackson.
The Kuratowski Closure-Complement Theorem: If $(X, \tau)$ is a topological space and $A \subseteq X$ then at most 14 sets can be obtained from $A$ by taking closures and complements.
As stated in B.J. Gardner and M. Jackson, this remarkable theorem and related phenomena have been the concern of many authors. However, being not a researcher in Topology,
My Problem: I would expect to see more interesting applications of the Kuratowski theorem in other fields, even in some non-mathematical fields (such as computer science).
I failed to find related literatures through googling.