Sparse random graphs with clustering |
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Authors: | Béla Bollobás Svante Janson Oliver Riordan |
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Affiliation: | 1. Department of Pure Mathematics and Mathematical Statistics, University of Cambridge, Cambridge CB3 0WB, UK;2. Department of Mathematical Sciences, University of Memphis, Memphis, Tennessee 38152;3. Department of Mathematics, Uppsala University, Uppsala SE‐751 06, Sweden;4. Mathematical Institute, University of Oxford, Oxford OX1 3LB, UK |
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Abstract: | In 2007, we introduced a general model of sparse random graphs with (conditional) independence between the edges. The aim of this article is to present an extension of this model in which the edges are far from independent, and to prove several results about this extension. The basic idea is to construct the random graph by adding not only edges but also other small graphs. In other words, we first construct an inhomogeneous random hypergraph with (conditionally) independent hyperedges, and then replace each hyperedge by a (perhaps complete) graph. Although flexible enough to produce graphs with significant dependence between edges, this model is nonetheless mathematically tractable. Indeed, we find the critical point where a giant component emerges in full generality, in terms of the norm of a certain integral operator, and relate the size of the giant component to the survival probability of a certain (non‐Poisson) multi‐type branching process. While our main focus is the phase transition, we also study the degree distribution and the numbers of small subgraphs. We illustrate the model with a simple special case that produces graphs with power‐law degree sequences with a wide range of degree exponents and clustering coefficients. © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 38, 269–323, 2011 |
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Keywords: | random graphs clustering phase transition |
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