Example Tree
Connected (from the root), acyclic, root has indegree 0, all other nodes have indegree 1. A node with outdegree 0 is a leaf. Otherwise it’s an internal node. If (ni, nj) is in RT then ni is the parent of nj and nj is a child of ni The root is at depth 0. If n is at depth d, then a child of n is at depth d+1. A leaf has height 0. The height of an internal node is 1 + the maximum of the heights of its children. The height* of a tree is 1 + height of its root. The children of a node are considered unordered. The links are called edges or arcs or branches. (*) Note difference from Sahni’s definition of height.