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Multilevel Graph Clustering with Density-Based Quality Measures

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4.7 Comparison to Published Resultsgraph |V | |E| article modularity ML-KL-density ML-KL-rwkarate 34 78 [2] 0.4197 (4) 0.41978 (4) 0.41978 (4)dolphins 62 159 [2] 0.529 0.52586 (5) 0.52772 (5)polBooks 105 441 [2] 0.5272 0.52560 (6) 0.52723 (5)afootball 115 613 [2] 0.6046 0.59419 (7) 0.60582 (10)jazz 198 2742 [23] 0.4452 (5) 0.44487 (4) 0.44514 (4)celegans metabolic 453 2040 [2] 0.450 0.45090 (9) 0.44992 (8)circuit s838 512 819 [69] 0.815 (13) 0.81551 (15) 0.81550 (15)email 1133 5451 [2] 0.579 0.57767 (11) 0.58137 (9)hep-th main 5835 13815 [21] 0.707 (114) 0.85523 (57) 0.85629 (59)Erdos02 6927 11850 [65] 0.6817 (20) 0.71611 (39) 0.71639 (39)PGPgiantcompo 10680 24316 [58] 0.855 0.88392 (102) 0.88462 (96)cond-mat-2003 main 27519 116181 [65] 0.7251 (44) 0.81377 (77) 0.81586 (78)Table 4.11: Comparison to Published Resultsfrom 1995 to 2003. Vertices represent authors and edges connect co-authors. Theedges are weighted as described in [61]. Here only the largest component containing27519 vertices is used.Extremal Optimization discovered 647 clusters <strong>with</strong> modularity 0.6790 [23]. Latermuch better clusterings were found. Newman’s recursive spectral bisection yielded0.723 [58] and greedy joining combined <strong>with</strong> pre-coarsening found 44 clusters <strong>with</strong>modularity 0.7251 [65]. Of the own algorithms the multi-level refinement ML-KLdensityproduced 77 clusters <strong>with</strong> 0.81377. A better clustering <strong>with</strong> 78 clustersand modularity 0.81586 was found by ML-KL-rw. However even better clusteringswere discovered in experiments. For example one <strong>with</strong> 82 clusters and modularity0.81718.4.7.2 SummaryThe Table 4.11 summarizes the clustering results. For each graph the best modularityfound in the literature and the modularity computed <strong>with</strong> the two multi-levelalgorithms ML-KL-density and ML-KL-rw is given. The graphs are sorted by thenumber of vertices and the best modularity on each graph is marked in bold.On smaller graphs optimal or at least very good clusterings were obtained <strong>with</strong>the Linear Programming methods from [2] and [13]. In these cases the multi-levelalgorithms found comparable good clusterings. Only few published results for biggraphs exist. There the multi-level algorithm ML-KL-rw performed much betterthan other methods. Still the clusterings found by experimental configurations showthat on some graphs better results are possible. But these were found more byfortunate circumstances than by a reliable, systematic search.85

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