Network theory

About: Network theory is a research topic. Over the lifetime, 2257 publications have been published within this topic receiving 109864 citations.

QUBE: a quick algorithm for updating betweenness centrality

Abstract: The betweenness centrality of a vertex in a graph is a measure for the participation of the vertex in the shortest paths in the graph. The Betweenness centrality is widely used in network analyses. Especially in a social network, the recursive computation of the betweenness centralities of vertices is performed for the community detection and finding the influential user in the network. Since a social network graph is frequently updated, it is necessary to update the betweenness centrality efficiently. When a graph is changed, the betweenness centralities of all the vertices should be recomputed from scratch using all the vertices in the graph. To the best of our knowledge, this is the first work that proposes an efficient algorithm which handles the update of the betweenness centralities of vertices in a graph. In this paper, we propose a method that efficiently reduces the search space by finding a candidate set of vertices whose betweenness centralities can be updated and computes their betweenness centeralities using candidate vertices only. As the cost of calculating the betweenness centrality mainly depends on the number of vertices to be considered, the proposed algorithm significantly reduces the cost of calculation. The proposed algorithm allows the transformation of an existing algorithm which does not consider the graph update. Experimental results on large real datasets show that the proposed algorithm speeds up the existing algorithm 2 to 2418 times depending on the dataset.

7. The Politics of Networks: Interests, Power, and Human Rights Norms

Abstract: Despite considerable interest in political networks, especially transnational advocacy networks (TANs), political scientists have imported few insights from network theory into their studies. His essay aims to begin an exchange between network theorists and political scientists by addressing two related questions. How can network theory inform the study of international relations, particularly in the examination of TANs? Conversely, what problems arise in political phenomena that can enrich network theory? We make two general arguments focusing on the process of norm emergence in networks based on the history of global human rights norms and the formation of Amnesty International. First, political power can be an emergent property of networks, found most likely in scale-free structures. That is, central (or more connected) nodes can influence a network directly or indirectly and thereby shape the ends towards which the nodes collectively move. Second, norms are also emergent properties of networks. In the earliest stages of change, many norms compete for acceptance and many potential networks built on different norms or combinations of norms exist but are not yet activated. We argue that the network which eventually emerges is not a function of the inherent "goodness" of one set of norms over another, since the quality of any norm is difficult to judge prior to its manifestation in a network of shared adherents. Rather, at least in the case of human rights, the crystallization of the observed network from the range of possible alternatives preceded the widespread acceptance of the norm and occurred as a result of a central node that exercised agenda-setting power by controlling the flow of information in the network.

Social networks in the lek-mating wire-tailed manakin (Pipra filicauda).

Abstract: How social structure interacts with individual behaviour and fitness remains understudied despite its potential importance to the evolution of cooperation. Recent applications of network theory to social behaviour advance our understanding of the role of social interactions in various contexts. Here we applied network theory to the social system of lek-mating wire-tailed manakins (Pipra filicauda, Pipridae, Aves). We analysed the network of interactions among males in order to begin building a comparative framework to understand where coordinated display behaviour lies along the continuum from solitary to obligately cooperative dual-male displays in the family Pipridae. Network degree (the number of links from a male to others) ranged from 1 to 10, with low mean and high variance, consistent with the theory for the evolution of cooperation within social networks. We also assessed factors that could predict social and reproductive success of males. Four network metrics, degree, eigenvector centrality, information centrality and reach, some of which assess circuitous as well as the shortest (geodesic) paths of male connectivity, predicted male social rise. The duration of a male's territorial tenure during the 4 years of the study predicted his probability of siring offspring.

Locating influential nodes via dynamics-sensitive centrality.

Abstract: With great theoretical and practical significance, locating influential nodes of complex networks is a promising issue. In this paper, we present a dynamics-sensitive (DS) centrality by integrating topological features and dynamical properties. The DS centrality can be directly applied in locating influential spreaders. According to the empirical results on four real networks for both susceptible-infected-recovered (SIR) and susceptible-infected (SI) spreading models, the DS centrality is more accurate than degree, k-shell index and eigenvector centrality.