T1
Description: If $a, b \in X$, there exist open sets $U_a$ and $U_b$ containing $a$ and $b$ respectively, such that $b \notin U_a$ and $a \notin U_b$.
Description: If $a, b \in X$, there exist open sets $U_a$ and $U_b$ containing $a$ and $b$ respectively, such that $b \notin U_a$ and $a \notin U_b$.