Related work. Several notions of node centrality have been used in the past. Degree centrality (DC) of a node is the number of its neighbors, i.e., its degree. Alternatively, DC can be normalized by dividing the degree with n{1, where n is the number of nodes in the network. Betweenness centrality (BWC) of a node is the sum, over all node pairs i and j in the network, of the percentage of all shortest paths between i and j in the network that go through the node of interest. Subgraph centrality (SC) of a node is a weighted sum of the numbers of all closed walks of different lengths in the network starting and ending at the node. These closed walks are related to partial subgraphs of a network, e.g., a closed walk with four nodes can ''go through'' different subgraphs on four nodes, such as along the same edge AB twice (as described above: from node A to node B along edge AB, then back to A along the same edge and then again from A to B and back to A along the same edge), or along a 4-node cycle ABCD that includes edge AB (along the ''square'' from node A to node B to node C to node D and back to A; this is regardless of whether edges CA and DB that ''go along the diagonal of the square'' exist) etc. The above mentioned sum is weighted so that the contribution of the closed walks decreases as the length of the walks increases, i.e., shorter walks (smaller subgraphs) have higher weight.