# Definition:Reflexive Transitive Closure/Reflexive Closure of Transitive Closure

Let $\mathcal R$ be a relation on a set $S$.
The reflexive transitive closure of $\mathcal R$ is denoted $\mathcal R^*$, and is defined as the reflexive closure of the transitive closure of $\mathcal R$:
$\mathcal R^* = \left({\mathcal R^+}\right)^=$