In a first countable space any point that is adherent to a set S is also the limit of a sequence in S.(adsbygoogle = window.adsbygoogle || []).push({});

In my head, this seems obvious, but I can't seem to get it on paper.. I know that is has to do with inverse functions preserving unions and intersections, but can't seem to write the proof out.

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# First Countable

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