\begin{definition}[Definition:Saturation (Group Action)/Definition 2]
Let $G$ be a group acting on a set $X$.
Let $S \subset X$ be a subset.
The '''saturation of $S$''' is the union of its images under the group action:
:$\overline S = \ds \bigcup_{g \mathop \in G} g S$
Category:Definitions/Group Actions
\end{definition}