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Scale-free networks are rare
Nature Communications, 10 (1): 1017 (04.03.2019)
DOI: 10.1038/s41467-019-08746-5
Аннотация
Real-world networks are often claimed to be scale free, meaning that the fraction of nodes with degree k follows a power law k−$\alpha$, a pattern with broad implications for the structure and dynamics of complex systems. However, the universality of scale-free networks remains controversial. Here, we organize different definitions of scale-free networks and construct a severe test of their empirical prevalence using state-of-the-art statistical tools applied to nearly 1000 social, biological, technological, transportation, and information networks. Across these networks, we find robust evidence that strongly scale-free structure is empirically rare, while for most networks, log-normal distributions fit the data as well or better than power laws. Furthermore, social networks are at best weakly scale free, while a handful of technological and biological networks appear strongly scale free. These findings highlight the structural diversity of real-world networks and the need for new theoretical explanations of these non-scale-free patterns.
