\begin{definition}[Definition:Minimal Element/Definition 2]
Let $\struct {S, \RR}$ be a relational structure.
Let $T \subseteq S$ be a subset of $S$.
An element $x \in T$ is a '''minimal element (under $\RR$) of $T$''' {{iff}}:
:$\neg \exists y \in T: y \mathrel {\RR^\ne} x$
where $y \mathrel {\RR^\ne} x$ denotes that $y \mathrel \RR x$ but $y \ne x$.
\end{definition}