Two complementary representations of a scale-free network

Nacher, J. C.; Yamada, T.; Goto, S.; Kanehisa, M.; Akutsu, T.

Two complementary representations of a scale-free network

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Description

Several studies on real complex networks from different fields as biology, economy, or sociology have shown that the degree of nodes (number of edges connected to each node) follows a scale-free power-law distribution like $P(k)\approx k^{-γ}$, where $P(k)$ denotes the frequency of the nodes that are connected to $k$ other nodes. Here we have carried out a study on scale-free networks, where a line graph transformation (i.e., edges in an initial network are transformed into nodes) is applied to a power-law distribution. Our results indicate that a power-law distribution as $P(k)\approx k^{-γ+1}$ is found for the transformed network together with a peak for low-degree nodes. In the present work we show a parametrization of this behaviour and discuss its application to real networks as metabolic networks, protein-protein interaction network and World Wide Web.
18 pages, 8 figures. Minor changes. One figure added