Is the Semantic Web a Small World?

In this paper, we describe a structural analysis of social networks on the Semantic Web. We performed a comprehensive analysis of graph-theoretical properties of online social networks based on the Friend-ofa-Friend (FOAF) ontology. Of particular interest were properties related to the small-world phenomenon. More than 1.6 million FOAF documents collected on the Semantic Web were analyzed in depth. Most of the FOAF documents have been created and published by social networking services, blog hosting services, or combinations of the two; only a fractional amount are maintained by individuals. We identified the largest strongly connected components of various community networks and analyzed them in regard to the small-world phenomenon. Interestingly, all components examined exhibited a characteristic path length comparable to the smallest length achievable for a graph of the respective size, and the clustering coefficient was much greater than expected for an equivalent random graph; along with power law degree distributions, both are typical features of small-world graphs.