Detecting communities in complex networks accurately is a prime challenge, preceding further analyses of network characteristics and dynamics. Until now, community detection took into account only positively valued links, while many actual networks also feature negative links. We extend an existing (spin glass) approach to incorporate negative links as well, resulting in a method similar to the clustering of signed graphs, but more accurate and more general. To illustrate our method, we applied it to a network of international alliances and disputes. Using data from 1993{2001, it turns out that the world can be divided into six power blocs similar to Huntington’s civilizations, with some notable exceptions.

This book introduces social networks to a general audience, from novices in all kinds of fields to experts wanting to catch up, and from academics on the one hand to practitioners in consultancy, management, policy, and social work on the other hand. Sophisticated models are lucidly explained and comprehensible without math (which is put in boxes, footnotes, or references), and are illustrated with network diagrams and examples ranging from anthropology to organizational sociology. A free and easy to use software tool - R’s igraph package - is explained in the final chapter so readers themselves can depict and analyze networks of interest to them. It includes a Graphical User Interface (see brief manual) that can perform a limited subset of igraph’s options in a simple and user friendly way.

This study contributes to earlier studies aimed at the question of whether the welfare state crowds out social capital or not by examining to what extent the welfare state affects the value of social capital. This article investigates the effects of three sources of social capital on occupational prestige and tests whether these effects are moderated by welfare state effort in terms of social spending. Multi-level analyses based on European Social Survey (ESS) 2002/03 and International Monetary Fund (IMF) data, including 39,299 people from 24 European countries, provides evidence that welfare state effort decreases the value of social capital.