Conference articles
Characterization of FriendFeed - A Web-based Social Aggregation Service.
In: .
2009.
T. Gupta, S. Garg, A. Mahanti, N. Carlsson and M. Arlitt.
[doi]
[abstract]
[BibTeX]
Many Web users have accounts with multiple different social networking services. This scenario has prompted development of "social aggregation" services such as FriendFeed that aggregate the information available through various services. Using five weeks of activity of more than 100,000 FriendFeed users, we consider questions such as what types of services users aggregate content from, the relative popularity of services, who follows the aggregated content feeds, and why.
Journal articles
Fast unfolding of communities in large networks.
J. Stat. Mech:P10008, 2008.
V.D. Blondel, J.L. Guillaume, R. Lambiotte and E.L.J.S. Mech.
[BibTeX]
Conference articles
Logsonomy - Social Information Retrieval with Logdata.
In:
HT '08: Proceedings of the Nineteenth ACM Conference on Hypertext and Hypermedia, pages 157-166.
ACM, New York, NY, USA, 2008.
Beate Krause, Robert Jäschke, Andreas Hotho and Gerd Stumme.
[doi]
[abstract]
[BibTeX]
Social bookmarking systems constitute an established
part of the Web 2.0. In such systems
users describe bookmarks by keywords
called tags. The structure behind these social
systems, called folksonomies, can be viewed
as a tripartite hypergraph of user, tag and resource
nodes. This underlying network shows
specific structural properties that explain its
growth and the possibility of serendipitous
exploration.
Today’s search engines represent the gateway
to retrieve information from the World Wide
Web. Short queries typically consisting of
two to three words describe a user’s information
need. In response to the displayed
results of the search engine, users click on
the links of the result page as they expect
the answer to be of relevance.
This clickdata can be represented as a folksonomy
in which queries are descriptions of
clicked URLs. The resulting network structure,
which we will term logsonomy is very
similar to the one of folksonomies. In order
to find out about its properties, we analyze
the topological characteristics of the tripartite
hypergraph of queries, users and bookmarks
on a large snapshot of del.icio.us and
on query logs of two large search engines.
All of the three datasets show small world
properties. The tagging behavior of users,
which is explained by preferential attachment
of the tags in social bookmark systems, is
reflected in the distribution of single query
words in search engines. We can conclude
that the clicking behaviour of search engine
users based on the displayed search results
and the tagging behaviour of social bookmarking
users is driven by similar dynamics.
Journal articles
Planetary-scale views on a large instant-messaging network.
, 2008.
J. Leskovec and E. Horvitz.
[doi]
[BibTeX]
The network of scientific collaborations within the European framework programme.
Physica A: Statistical Mechanics and its Applications, 384(2):675 - 683, 2007.
Juan A. Almendral, J.G. Oliveira, L. López, J.F.F. Mendes and Miguel A.F. Sanjuán.
[doi]
[abstract]
[BibTeX]
We use the emergent field of complex networks to analyze the network of scientific collaborations between entities (universities, research organizations, industry related companies,...) which collaborate in the context of the so-called framework programme. We demonstrate here that it is a scale-free network with an accelerated growth, which implies that the creation of new collaborations is encouraged. Moreover, these collaborations possess hierarchical modularity. Likewise, we find that the information flow depends on the size of the participants but not on geographical constraints.
Miscellaneous
Maximizing Modularity is hard.
2006. cite arxiv:physics/0608255 Comment: 10 pages, 1 figure.
U. Brandes, D. Delling, M. Gaertler, R. Goerke, M. Hoefer, Z. Nikoloski and D. Wagner.
[doi]
[abstract]
[BibTeX]
Several algorithms have been proposed to compute partitions of networks
into communities that score high on a graph clustering index called
modularity. While publications on these algorithms typically contain
experimental evaluations to emphasize the plausibility of results,
none of these algorithms has been shown to actually compute optimal
partitions. We here settle the unknown complexity status of modularity
maximization by showing that the corresponding decision version is
NP-complete in the strong sense. As a consequence, any efficient,
i.e. polynomial-time, algorithm is only heuristic and yields suboptimal
partitions on many instances.
Conference articles
Semantic Network Analysis of Ontologies.
In:
The Semantic Web: Research and Applications, series Lecture Notes in Computer Science.
Springer, 2006.
Proceedings of the 3rd European Semantic Web Conference, Budva, Montenegro
Bettina Hoser, Andreas Hotho, Robert Jäschke, Christoph Schmitz and Gerd Stumme.
[abstract]
[BibTeX]
A key argument for modeling knowledge in ontologies is the easy re-use and re-engineering of the knowledge. However, current ontology engineering tools provide only basic functionalities for analyzing ontologies. Since ontologies can be considered as graphs, graph analysis techniques are a suitable answer for this need. Graph analysis has been performed by sociologists for over 60 years, and resulted in the vivid research area of Social Network Analysis (SNA). While social network structures currently receive high attention in the Semantic Web community, there are only very
few SNA applications, and virtually none for analyzing the
structure of ontologies.
We illustrate the benefits of applying SNA to ontologies and the Semantic Web, and discuss which research topics arise on the edge between the two areas. In particular, we discuss how different notions of centrality describe the core content and structure of an ontology. From the rather simple notion of degree centrality over betweenness centrality to the more complex eigenvector centrality, we illustrate the insights these measures provide on two ontologies, which are different in purpose, scope, and size.
Structure and evolution of online social networks.
In:
KDD '06: Proceedings of the 12th ACM SIGKDD international conference on Knowledge discovery and data mining, pages 611-617.
ACM, New York, NY, USA, 2006.
Ravi Kumar, Jasmine Novak and Andrew Tomkins.
[doi]
[abstract]
[BibTeX]
In this paper, we consider the evolution of structure within large online social networks. We present a series of measurements of two such networks, together comprising in excess of five million people and ten million friendship links, annotated with metadata capturing the time of every event in the life of the network. Our measurements expose a surprising segmentation of these networks into three regions: singletons who do not participate in the network; isolated communities which overwhelmingly display star structure; and a giant component anchored by a well-connected core region which persists even in the absence of stars.We present a simple model of network growth which captures these aspects of component structure. The model follows our experimental results, characterizing users as either passive members of the network; inviters who encourage offline friends and acquaintances to migrate online; and linkers who fully participate in the social evolution of the network.
Journal articles
Towards a theory of scale-free graphs: Definition, properties, and implications.
Internet Mathematics, 2(4):431-523, 2005.
L. Li, D. Alderson, J.C. Doyle and W. Willinger.
[doi]
[BibTeX]
Lexical and semantic clustering by web links.
Journal of the American Society for Information Science and Technology, 55(14):1261-1269, 2004.
F. Menczer.
[doi]
[BibTeX]
The structure and function of complex networks.
SIAM Review, 45(2):167-256, 2003.
M. E. J. Newman.
[BibTeX]
Why Social Networks Are Different from Other Types of Networks.
Phys. Rev. E, 68(3):036122, 2003.
M. E. J. Newman and Juyong Park.
[abstract]
[BibTeX]
We argue that social networks differ from most other types of networks, including technological and biological networks, in two important ways. First, they have nontrivial clustering or network transitivity and second, they show positive correlations, also called assortative mixing, between the degrees of adjacent vertices. Social networks are often divided into groups or communities, and it has recently been suggested that this division could account for the observed clustering. We demonstrate that group structure in networks can also account for degree correlations. We show using a simple model that we should expect assortative mixing in such networks whenever there is variation in the sizes of the groups and that the predicted level of assortative mixing compares well with that observed in real-world networks.
Community structure in social and biological networks.
PNAS, 99(12):7821-7826, 2002.
M. Girvan and M. E. J. Newman.
[BibTeX]
Email networks and the spread of computer viruses.
Phys. Rev. E, 66(3):035101, 2002.
M. E. J. Newman, Stephanie Forrest and Justin Balthrop.
[BibTeX]
Large-scale topological and dynamical properties of the Internet.
Physical Review E, 65(6):66130, 2002.
A. Vázquez, R. Pastor-Satorras and A. Vespignani.
[doi]
[BibTeX]
Dynamical and correlation properties of the Internet.
Physical Review Letters, 87(25):258701, 2001.
R. Pastor-Satorras, A. Vázquez and A. Vespignani.
[doi]
[BibTeX]
Classes of small-world networks.
PNAS, 97(21), 2000.
L. A. N. Amaral, A. Scala, M. Barthélémy and H. E. Stanley.
[BibTeX]
Graph structure in the web.
Computer Networks, 33(1-6):309-320, 2000.
A. Broder, R. Kumar, F. Maghoul, P. Raghavan, S. Rajagopalan, R. Stata, A. Tomkins and J. Wiener.
[doi]
[BibTeX]
Emergence of scaling in random networks.
Science, 286(5439):509-512, 1999.
A. L. Barabasi and R. Albert.
[doi]
[abstract]
[BibTeX]
Systems as diverse as genetic networks or the World Wide Web are best described as networks with complex topology. A common property of many large networks is that the vertex connectivities follow a scale-free power-law distribution. This feature was found to be a consequence of two generic mechanisms: (i) networks expand continuously by the addition of new vertices, and (ii) new vertices attach preferentially to sites that are already well connected. A model based on these two ingredients reproduces the observed stationary scale-free distributions, which indicates that the development of large networks is governed by robust self-organizing phenomena that go beyond the particulars of the individual systems.
On Random Graphs.
Publications Mathematicae, 6:290, 1959.
Pal Erdős and Alfréd Rényi.
[BibTeX]