\begin{definition}[Definition:Separated Sets/Definition 1]
Let $T = \struct {S, \tau}$ be a topological space.
Let $A, B \subseteq S$.
$A$ and $B$ are '''separated (in $T$)''' {{iff}}:
:$A^- \cap B = A \cap B^- = \O$
where:
:$A^-$ denotes the closure of $A$ in $T$
:$\O$ denotes the empty set.
$A$ and $B$ are said to be '''separated sets (of $T$)'''.
\end{definition}