Definition:Arborescence/Definition 2

Definition
Let $G = \left({V, A}\right)$ be a directed graph.

Let $r \in V$.

$G$ is an arborescence of root $r$ :


 * $(1): \quad$ $G$ is an orientation of a tree
 * $(2): \quad$ For each $v \in V$, $v$ is reachable from $r$.

Also see

 * Equivalence of Definitions of Arborescence