[isabelle] new in the AFP: The Kuratowski Closure-Complement Theorem



And another new entry in the AFP:

The Kuratowski Closure-Complement Theorem
by Peter Gammie and Gianpaolo Gioiosa

We discuss a topological curiosity discovered by Kuratowski (1922): the fact that the number of distinct operators on a topological space generated by compositions of closure and complement never exceeds 14, and is exactly 14 in the case of R. In addition, we prove a theorem due to Chagrov (1982) that classifies topological spaces according to the number of such operators they support.

https://www.isa-afp.org/entries/Kuratowski_Closure_Complement.html

Enjoy!
Gerwin





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