T3
Description: If $A$ is a closed set and $b$ is a point not in $A$, there exist disjoint open sets $U_A$ and $U_b$ containing $A$ and $b$ respectively.
Description: If $A$ is a closed set and $b$ is a point not in $A$, there exist disjoint open sets $U_A$ and $U_b$ containing $A$ and $b$ respectively.