📚 Recommended Mathematics Books

Topology (Munkres)  |  General Topology (Engelking)  |  Counterexamples in Topology  |  Rudin's Analysis

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After proposing this conjecture I quickly found a counterexample:

$latex S = \left\{ (- a ; a) \mid a \in \mathbb{R}, 0 < a < 1 \right\}$, $latex f$ is the usual Kuratowski closure for $latex \mathbb{R}$.

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