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In a binary tree, each parent has a reference to its child nodes. There is a direction from each parent node to each of its child node as shown in the tree image below. So how come it is defined as an undirected graph? One more question I have regarding directed and undirected graphs. Is an undirected graph the same as a bi directional directed graph

Thanks BInary tree graph

Vadim Kotov
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kaka
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  • The picture strongly suggests that the binary tree is a _directed_ graph. What excactly makes you think it is (or should be termed as) an _undirected_ graph? This might be just a matter of definitions and conventions. – Codor Feb 02 '18 at 11:47

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It is also possible to interpret a binary tree as an undirected, rather than a directed graph, in which case a binary tree is an ordered, rooted tree.[5] Some authors use rooted binary tree instead of binary tree to emphasize the fact that the tree is rooted, but as defined above, a binary tree is always rooted.[6] A binary tree is a special case of an ordered K-ary tree, where k is 2.

Source: https://en.wikipedia.org/wiki/Binary_tree

Usually, we say a rooted tree is a directed graph.

Lerner Zhang
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