Showing papers on "Katz centrality published in 2005"

Centrality measures based on current flow

Abstract: We consider variations of two well-known centrality measures, betweenness and closeness, with a different model of information spread. Rather than along shortest paths only, it is assumed that information spreads efficiently like an electrical current. We prove that the current-flow variant of closeness centrality is identical with another known measure, information centrality, and give improved algorithms for computing both measures exactly. Since running times and space requirements are prohibitive for large networks, we also present a randomized approximation scheme for current-flow betweenness.

Models and Methods in Social Network Analysis: Extending Centrality

Abstract: In this chapter, we discuss three ways to extend the basic concept of centrality. The first extends centrality to apply to groups in addition to individual actors. This extension makes it possible to evaluate the relative centrality of different teams or departments within an organization, or to assess whether a particular ethnic minority in a society is more integrated than another. The second extends the concept of centrality to apply to 2mode data in which the data consist of a correspondence between two kinds of nodes, such as individuals and the events they participate in. In the past, researchers have dealt with such data by converting them to standard network data (with considerable loss of information). The extension to 2-mode data means that we can apply the tools and concepts of centrality directly to original 2-mode dataset. The third broadens the centrality concept into a model of the core/periphery structure of a network. With this technique we can evaluate the extent to which a network revolves around a core group of nodes.

Network competition - the co-existence of hub-and-spoke and point-to-point

Abstract: Airlines network choices are analysed to describe the co-existence of alternative business models: the full service model based on the hub-and-spoke (HS) system and the low cost model based on point-to-point (PP) system. The analysis is carried on both theoretically and empirically. In the theoretical part, we show that the rise of the low costs business model can be the consequence of a simple two-player game. When two carriers compete in designing their network configurations (HS or PP), asymmetric equilibria emerge, i.e. one carrier will choose HS and the other PP. Full service carriers are stuck to a HS configuration to serve intercontinental destinations, whilst non-flag carriers implement a point-to-point network. In the second part, the recent network evolution in Europe is empirically evaluated by means of different spatial measures of concentration, such as Gini index, Freeman centrality index and Bonacich centrality. In addition, we also provide an airline-specific measure of centrality based on scheduled time comparison of direct to one-stop services. Spatial measures of centrality capture a reduction of centrality in non-flag carriers and small changes in the network centrality of flag carriers. Indeed, the time-based measure of centrality suggests an increase of centrality of flag carriers.