Towards Demarcation and Modeling of Small Sub-Communities/Groups in P2P Social Networks

In centralized virtual social networking platforms, models for sub-structures like sub-communities or groups such as Facebook's groups exist. We investigate in how far these declared groups are dense sub-networks in a study using declared groups in a German Facebook clone (StudiVZ) as an example. While many such groups are large and sparse ``pseudo´´-structures which should be seen as labels or tags for profile extension, the result of the study is that a substantial share of these declared groups (especially the smaller ones) have a high network density with respect to various measures of density. We conclude that these can be considered socially ``valid´´ models of sub-structures (groups, small sub-communities etc.). In a second line of thought we argue that decentralized / Peer-to-Peer Social Networking appears to be a very promising answer to the problem of many co-existing virtual social network platforms and the resulting problems of having to keep multiple identities and not being able to access the network overlapping the platform boundaries in a coherent manner. Both argumentations together imply that a suitable approach for modeling and demarcating sub-structures (e.g. sub-communities) in decentralized P2P social networking is necessary. We conclude by discussing candidate approaches for the problem.