Modularity of Erdos-Rényi random graphs

For a given graph G, modularity gives a score to each vertex partition, with higher values taken to indicate that the partition better captures community structure in G. The modularity q∗(G) (where 0 ≤ q∗(G) ≤ 1) of the graph G is defined to be the maximum over all vertex partitions of the modularit...

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Main Authors: McDiarmid, C, Skerman, F
Format: Conference item
Published: Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik 2018
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author McDiarmid, C
Skerman, F
author_facet McDiarmid, C
Skerman, F
author_sort McDiarmid, C
collection OXFORD
description For a given graph G, modularity gives a score to each vertex partition, with higher values taken to indicate that the partition better captures community structure in G. The modularity q∗(G) (where 0 ≤ q∗(G) ≤ 1) of the graph G is defined to be the maximum over all vertex partitions of the modularity value. Given the prominence of modularity in community detection, it is an important graph parameter to understand mathematically. For the Erdos-Rényi random graph Gn,pwith n vertices and edge-probability p, the likely modularity has three distinct phases. For np ≤ 1 + o(1) the modularity is 1 + o(1) with high probability (whp), and for np → 1 the modularity is o(1) whp. Between these regions the modularity is non-trivial: for constants 1 < c0 ≤ c1 there exists δ > 0 such that when c0 ≤ np ≤ c1 we have δ < q∗(G) < 1 - δ whp. For this critical region, we show that whp q∗(Gn, p) has order (np)-1/2, in accord with a conjecture by Reichardt and Bornholdt in 2006 (and disproving another conjecture from the physics literature).
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spelling oxford-uuid:cd71fc3d-a646-4bcc-9ead-86cfbaf54f572022-03-27T07:28:48ZModularity of Erdos-Rényi random graphsConference itemhttp://purl.org/coar/resource_type/c_5794uuid:cd71fc3d-a646-4bcc-9ead-86cfbaf54f57Symplectic Elements at OxfordSchloss Dagstuhl--Leibniz-Zentrum fuer Informatik2018McDiarmid, CSkerman, FFor a given graph G, modularity gives a score to each vertex partition, with higher values taken to indicate that the partition better captures community structure in G. The modularity q∗(G) (where 0 ≤ q∗(G) ≤ 1) of the graph G is defined to be the maximum over all vertex partitions of the modularity value. Given the prominence of modularity in community detection, it is an important graph parameter to understand mathematically. For the Erdos-Rényi random graph Gn,pwith n vertices and edge-probability p, the likely modularity has three distinct phases. For np ≤ 1 + o(1) the modularity is 1 + o(1) with high probability (whp), and for np → 1 the modularity is o(1) whp. Between these regions the modularity is non-trivial: for constants 1 < c0 ≤ c1 there exists δ > 0 such that when c0 ≤ np ≤ c1 we have δ < q∗(G) < 1 - δ whp. For this critical region, we show that whp q∗(Gn, p) has order (np)-1/2, in accord with a conjecture by Reichardt and Bornholdt in 2006 (and disproving another conjecture from the physics literature).
spellingShingle McDiarmid, C
Skerman, F
Modularity of Erdos-Rényi random graphs
title Modularity of Erdos-Rényi random graphs
title_full Modularity of Erdos-Rényi random graphs
title_fullStr Modularity of Erdos-Rényi random graphs
title_full_unstemmed Modularity of Erdos-Rényi random graphs
title_short Modularity of Erdos-Rényi random graphs
title_sort modularity of erdos renyi random graphs
work_keys_str_mv AT mcdiarmidc modularityoferdosrenyirandomgraphs
AT skermanf modularityoferdosrenyirandomgraphs