Measures of network topology that are more constraining than degrees might help resolve these controversies. Hence, various topological centrality concepts have been formulated. Examples include the betweenness centrality [35] , according to which nodes that occur in many of the shortest paths in a network have high centrality, and the subgraph centrality, which counts the number of closed walks of different lengths in the network starting and ending at the node in question and according to which nodes that participate in a large number of such walks have high centrality [44, 45] .