Distribution of centrality measures on undirected random networks via the cavity method

Bartolucci, Silvia, Caccioli, Fabio, Caravelli, Francesco and Vivo, Pierpaolo (2024) Distribution of centrality measures on undirected random networks via the cavity method. Proceedings of the National Academy of Sciences of the United States of America, 121 (40). ISSN 0027-8424

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Abstract

The Katz centrality of a node in a complex network is a measure of the node’s importance as far as the flow of information across the network is concerned. For ensembles of locally tree-like undirected random graphs, this observable is a random variable. Its full probability distribution is of interest but difficult to handle analytically because of its “global” character and its definition in terms of a matrix inverse. Leveraging a fast Gaussian Belief Propagation-Cavity algorithm to solve linear systems on tree-like structures, we show that i) the Katz centrality of a single instance can be computed recursively in a very fast way, and ii) the probability P(K ) that a random node in the ensemble of undirected random graphs has centrality K satisfies a set of recursive distributional equations, which can be analytically characterized and efficiently solved using a population dynamics algorithm. We test our solution on ensembles of Erdős-Rényi and Scale Free networks in the locally tree-like regime, with excellent agreement. The analytical distribution of centrality for the configuration model conditioned on the degree of each node can be employed as a benchmark to identify nodes of empirical networks with over- and underexpressed centrality relative to a null baseline. We also provide an approximate formula based on a rank-1 projection that works well if the network is not too sparse, and we argue that an extension of our method could be efficiently extended to tackle analytical distributions of other centrality measures such as PageRank for directed networks in a transparent and user-friendly way.

Item Type:	Article
Additional Information:	© 2024 the Author(s)
Divisions:	Systemic Risk Centre
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Date Deposited:	08 Oct 2024 11:30
Last Modified:	12 Dec 2024 04:31
URI:	http://eprints.lse.ac.uk/id/eprint/125657

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