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Counterexample

Is this true?

A compact T1T_{1} space is Hausdorff

No — it is false.

The counterexample

An infinite set with the cofinite topology

Why it fails

Compact and T1T_{1} but any two non-empty open sets intersect.

Go deeper· Explained in full in The counterexample zoo: cofinite, cocountable, Sorgenfrey, Cantor· Asked in CSIR NET June 2024· From Topology › Standard spaces: cofinite, cocountable, Sorgenfrey, Cantor set

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