Why is cofinite topology on a countable set a second countable space?
41661
Show that the set of all finite subsets of $\mathbb{N}$ is countable.
36315
Is $[0,1]$ a countable disjoint union of closed sets?
59275
If $X$ is an infinite set, then $X$ with the discrete topology is not compact
71489
Countable product of Polish spaces
119649
Every metrizable space with a countable dense subset has a countable basis
91237
Every infinite set contains a countable subset
130981
Co-countable measure on uncountable set
4111
Outer measure is countably subadditive
87983
Examples of Separable Spaces that are not Second-Countable
70048
In which topologies do open sets maintain open under countable or arbitrary intersection?
127166
Specific example of a space that is separable but not second countable.
155168
Is the collection of finite subsets of $\mathbb{Z}$ countable?
75019
Infinite Cartesian product of countable sets is uncountable
95747
Number of countable subsets of $\mathbb{R}$
97697
Countable union of sets of cardinality $c$ has cardinality $c$
62793
$\mathbb{R}$ with the lower limit topology is not second-countable
130361
Basis for a topology with a countable number of sets