Community Structures in Social (Information) Networks

Speaker : Peter Marbach
University of Toronto
Date: 24/04/2019
Time: 2:00 pm - 3:00 pm
Location: Paris-Rennes Room (EIT Digital)


Communities play an important role in social networks. However while there exists a large body of work that formally models and studies macroscopic properties of social networks such as the degree distribution and diameter, less work is available on mathematical models for microscopic properties of communities in social networks. Creating such a model is the topic of this paper. Ideally this model should be simple enough to allow a formal analysis, yet be expressive enough to provide insights into important microscopic properties of communities in social networks. For the talk we focus on a particular type of social networks, to which we refer to as information networks, where agents (individuals) share/exchange information. Sharing/exchanging of information is an important aspect of the social networks, both for social networks that we form in our everyday lives, as well as for online social networks such as for example Twitter. The model that we use to characterize information networks has three important components: 1) the space of content that is being produced and consumed in the, 2) agent’s interests and ability to produce content, and 3) the utility that agents obtain for consuming and producing content. An interesting outcome of the analysis of this model is that albeit being very simple, indeed seems to be able to provide interesting insights into the microscopic structure of information communities. For example, the characterization of how content is being produced, i.e. which content each agent in a community produces, indeed matches what has been experimentally observed in real-life social networks. It also provides insight into how to design efficient community detection algorithm.


Peter Marbach was born in Lucerne, Switzerland. He received the Eidg. Dipl. El.-Ing. (1993) from the ETH Zurich, Switzerland, the M.S. (1994) in electrical engineering from the Columbia University, NY, U.S.A, and the Ph.D. (1998) in electrical engineering from the Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, U.S.A. He has been since 2000 with the Department of Computer Science of the University of Toronto. He has also been a visiting professor at Microsoft Research, Cambridge, UK, at the Ecole Polytechnique Federal at Lausanne (EPFL), Switzerland, and at the Ecole Normale Supérieure, Paris, France, and a post-doctoral fellow at Cambridge University, UK.
His research interests are in the fields of communication networks, in particular in the area of wireless networks, peer-to-peer networks, and social networks.