\begin{definition}[Definition:Reflexive Closure/Intersection of Reflexive Supersets]
Let $\RR$ be a relation on a set $S$.
Let $\QQ$ be the set of all reflexive relations on $S$ that contain $\RR$.
The '''reflexive closure''' of $\RR$ is denoted $\RR^=$, and is defined as:
:$\RR^= := \bigcap \QQ$
That is:
:$\RR^=$ is the intersection of all reflexive relations on $S$ containing $\RR$.
\end{definition}