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| Math Central | Quandaries & Queries |
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Question from Shabkhal, a parent: Show that the sum of in degrees of all the nodes of a simple digraph is equal to the sum of out degrees of all its nodes and this sum is equal to the number of edges of the graph. |
Hi Shabkhal,
Every arc has two ends. One end contributes to the out-degree of a vertex, and one contributes to the in-degree of a vertex.
Victoria
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