Definition:Rooted Subtree

Definition
Let $\left({T, r_T}\right)$ be a rooted tree.

A rooted subtree of $T$ is a rooted tree $\left({S, r_S}\right)$ such that:


 * $S$ is a subtree of $T$
 * $r_S = r_T$

Note that the second condition implies that $r_T \in S$.

Also see

 * Definition:Subtree (Graph Theory)