Dense subgraphs of sparse graphs (communities), which appear in most real-world complex networks, play an important role in many contexts. Computing them however is generally expensive. We propose here a measure of similarities between vertices based on random walks which has several important advantages: it captures well the community structure in a… (More)
Web 2.0 works with the principle of weak cooperation, where a huge amount of individual contributions build solid and structured sources of data. In this paper, we detail the main properties of this weak cooperation by illustrating them on the photo publication website Flickr, showing the variety of uses producing a rich content and the various procedures… (More)
Dense sub-graphs of sparse graphs (communities), which appear in most real-world complex networks, play an important role in many contexts. Most existing community detection algorithms produce a hierarchical structure of communities and seek a partition into communities that optimizes a given quality function. We propose new methods to improve the results… (More)
We study here Flickr groups in order to see whether they are actual communities or rather essentially thematic clusters. We describe a methodological framework for the analysis of networks of group members, measuring social density and tag dispersion among groups and give some results on a sample of 450 groups having around 500 members each.
— We propose to study the impact of a suite of policies on the performance of a multi-file distribution system that integrates CDN and P2P techniques. One of the policies is the peer contribution policy that decides the limited data rate and data volume to be contributed by each peer. The peer contribution policy is critical to maintaining the system's… (More)