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In a directed tree (below left), it is also required that no node has indegreeIndegree greater than one, i.e., that no node has more than one edge pointing to it. Therefore, it is possible that a directed graph has no cycles but it is not a directed tree – for example, consider the graph obtained by inverting the direction of all the edges in the graph below. A directed tree always has exactly one root (a node that has no edges pointing to it). Below, node A is the root.