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Harmonic CentralityDefinition
The denormalized reciprocal of the harmonic mean of all distances (even ∞).
Another extension to networks with disconnected components has been proposed by Opsahl (2010) and later studied by Boldi and Vigna (2014) in general directed graphs: The formula above, with the convention, defines harmonic centrality. It is a natural modification of Bavelas's definition of closeness following the general principle proposed by Marchiori and Latora (2000) that in networks with infinite distances the harmonic mean behaves better than the arithmetic mean. Indeed, Bavelas's closeness can be described as the denormalized reciprocal of the arithmetic mean of distances, whereas harmonic centrality is the denormalized reciprocal of the harmonic mean of distances. The harmonic mean H of the positive real numbers x1, x2, ..., xn > 0 is defined to be: See Information Centrality SoftwareReferences

See Holme & Ghoshal, Phys. Rev. Lett. 96, 098701 (2006), Eq. (1) for an earlier reference. (But I don't think it is such a great measure. It is an arbitrary combination of two aspects of networks—the component size distribution and the distances within the components—that rather should be kept separate.) 

Add Replay  written March 24, 2018, 12:14 pm by Petter Holme 