# Definition:Maximal/Relation

Let $\left({S, \mathcal R}\right)$ be a relational structure.
Let $T \subseteq S$ be a subset of $S$.
An element $x \in T$ is an $\mathcal R$-maximal element of $T$ if and only if:
$\forall y \in T: x \not \mathrel {\mathcal R} y$