\begin{definition}[Definition:Reflexive Transitive Closure/Reflexive Closure of Transitive Closure]
Let $\RR$ be a relation on a set $S$.
The '''reflexive transitive closure''' of $\RR$ is denoted $\RR^*$, and is defined as the reflexive closure of the transitive closure of $\RR$:
:$\RR^* = \paren {\RR^+}^=$
Category:Definitions/Relation Theory
\end{definition}