Does second countablity implies closed (or open) set in $X$ is a countable intersection of open sets in $X$

general-topologysecond-countable

Is $X$ is second countable implies or equivalent to Every closed(or open) set in $X$ is a countable intersection of open sets in $X$?


I know, metric space implies this by Closed set as a countable intersection of open sets, and Every open set in $\mathbb{R}$ is a countable union of closed sets. Also I know metric space is 1st countable but not 2nd countable.

If so How one can prove this statement?

Best Answer

The natural numbers $\ge 2$ endowed with the topology of the subsets that contain the divisors of each of their elements is second-countable, but not $G_\delta$.

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