Research by: Jiachen Sun, Rui Zhang, Ling Feng , Christopher P. Monterola, Xiao Ma, Céline Rozenblat, H. Eugene Stanley, Boris Podobnik, & Yanqing Hu
Interdependent networks are important since many real world systems have interactions at different levels, and such complexity often leads to new and rich emergent behaviors not present in single layer networks. Although much research has focused on the robustness to failure in multilayer interdependent networks, these studies have assumed that networks are unstructured. This is in sharp contrast to real-world networks that have internal community structures. For example, transportation networks have more connections within urban regions than between urban regions. A group of countries
usually have more economic ties within the group than with countries outside the group. A problem of particular interest is determining how these complex systems with a rich community structure behave under localized disruption.
Here, we present a generalized framework of interdependent multilayer network with community structure based on the mathematics of generating functions, and study cascading processes that occur across the entire network initiated by random damage disruption in a single community. Such a framework is generalizable to any number of layers of interdependent networks with an arbitrary number of communities.
Some of the interesting results include: One, in contrast to a single network, which is always more robust with enhanced community structure, interdependent networks showing strong community structure sometimes make systems more vulnerable. In cases of extremely strong community structures with very sparse intercommunity in one layer of network, a small change in the other layer of network’s community strength could induce abrupt changes in total systemic resilience if one community is under attack. This new finding adds to the growing knowledge of resilience of interdependent networks with community structure, in particular attacks on specific communities that is representative of realistic events like natural disaster and economic embargo.
Two, from the global business-flight networks taken as a proxy for the world economy, we observe that, as globalization weakens the community structure, the entire network is approaching a state in which there is a potential for abrupt disruptions in certain communities. This also leads to the finding that Asia strongly depends on North America and Europe economies but not the other way round. Our result is indicative for a broad range of systems which have community structures defined by geographic location and physical infrastructure.
On the empirical side, our methods can be similarly extended to study other real interdependent networks with community structures, to give better understanding of their dynamical behaviors for risk assessment, which then leads to the development of efficient risk mitigation strategies in those systems. Overall, this study answers the open question of how disruption in a community of one network propagates through the “global” network of networks.
To cite this article: Sun, J., Zhang, R., Feng, L., Monterola, C. P., Ma, X., Rozenblat, C., Stanley, H. E., Podobnik, B., & Hu, Y. (2019). Extreme risk induced by communities in interdependent networks. Communications Physics 2, 45. https://doi.org/10.1038/s42005-019-0144-6.
To access this article: https://doi.org/10.1038/s42005-019-0144-6
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