Homepage › Solution manuals › Theodore Gamelin › Introduction to Topology › Exercise 2.1.11 (Kuratowski's closure-complement problem)
Exercise 2.1.11 (Kuratowski's closure-complement problem)
Prove the following result, originally noted by Kuratowski: If is a subset of a topological space , then there are at most subsets of that can be obtained from by successively taking either complements or closures. Find a subset of such that exactly fourteen subsets of can be obtained from in this manner.