Particular Point Space is Separable

From ProofWiki
Jump to navigation Jump to search


Let $T = \struct {S, \tau_p}$ be a particular point space.

Then $T$ is separable.


By definition, $T$ is separable if and only if there exists a countable subset of $S$ which is everywhere dense in $T$.

Consider $U := \set p \subseteq S$.

By definition, $U$ is open in $T$.

From Closure of Open Set of Particular Point Space we have that $U^- = S$, where $U^-$ is the closure of $U$.

By definition, $U$ is everywhere dense in $T$.

$U$ is (trivially) countable.

Hence the result, by definition of a separable space.