Simplex 2012

Keynote lectures

Alain Barrat, Director of Research at the CNRS and Centre de Physique Théorique (France), and Cecilia Mascolo, Reader in Mobile Systems at the Computer Laboratory of the University of Cambridge (UK), will be delivering keynote lectures at SIMPLEX 2012.

Alain Barrat
Dynamical Networks: from Measurements to Models
Abstract: In the last decade, a significant research activity has developed in the context of complex networks, largely motivated by the fact that many systems can be represented by networks, that is to say a set of sites or vertices connected by ties. More recently, the issue of dynamic complex networks has emerged. In this talk, I will discuss several examples of dynamic networks, in order to highlight the importance of taking into account their temporal dimension. I will first discuss examples of infrastructure networks, and then focus on human interaction networks. In this context, I will present the SocioPatterns collaboration, in which we have developed an infrastructure capable of measuring social interactions in real-time in a limited space, such as conferences, offices, hospitals... and in which we study the corresponding dynamical social networks. I will present some results obtained by the deployment of this infrastructure, which reveal unexpected regularities in social interactions. I will also present a model of social dynamics that reproduces a number of empirical facts, and describe some studies of dynamical processes occurring on dynamical networks. I will conclude with prospects offered by the area of dynamic networks.
Short biography

Cecilia Mascolo
Space, Time and Social Ties: How Geographic Distance Shapes Online Social Networks
Abstract: While in the last years massive online social networks have become extremely popular, gathering and engaging millions of users, only recently these social services are becoming location-aware. This provides broad and fine grained data to investigate how spatial and social structure blend together, opening exciting research directions with promising scientific and practical applications. For instance, an open question about human social behavior is to understand whether, and how, spatial distance between two individuals affects their social interaction. In this talk we will present how the socio-spatial properties of online social networks can be studied and how social and spatial properties can be jointly exploited to build new systems and applications. We discuss a comprehensive analysis of the spatial properties of the social networks arising among users of three main popular online location-based services. We observe robust universal features across them: there is strong heterogeneity across users, with different characteristic spatial lengths of interaction across both their social ties and social triads. We extend these results with a detailed study of the temporal evolution of a social network with spatial information: since node degree and spatial distance simultaneously shape user connections, we describe and evaluate a gravitational model of network growth which is able to capture the social and spatial properties observed in real networks, confirming our findings. There a number of possible application of geo-social models for social networks and we illustrate the exploitation of our research in the design of a link prediction system for online social networks based on the places that users visit as well as a content cascade geographical spread prediction model which improves content caching on content delivery networks.
Short biography


The proceedings can be found here.

Technical program

Morning Sessions Chair: Raul Mondragon

9:00 - 9:30 Welcome to the Workshop

Session: Complex Network Analysis

9:30 - 09:50 Social Media - Are They Underpinned by Social or Interest-based Interactions
Katarzyna Musial and Nishanth Sastry
9:50 - 10:10 Publish-Subscribe Systems via Gossip: a Study Based on Complex Networks
Stefano Ferretti
10:10 - 10:30 Topological Trends of Internet Content Providers
Yuval Shavitt and Udi Weinsberg

10:30 - 11:00 Coffee Break

11:00 - 12:00 Keynote by Cecilia Mascolo: "Space, Time and Social Ties: How Geographic Distance Shapes Online Social Networks"

Session: Auction Design and Systems Dynamics

12:00 - 12:20 On Social Community Networks: The Problem of Cost Sharing
Ranjan Pal, Pan Hui and Aravind Kailas
12:20 - 12:40 The Dynamic Network Notation: Harnessing Network Effects in PaaS-Ecosystems
Ulrich Scholten, Robin Fischer and Christian Zirpins
12:40 - 13:50 Lunch

Afternoon Sessions Chair: Nishanth Sastry

Session: Human Contacts

13:50 - 14:10 Quality Distributed Community Formation for Data Delivery in Pocket Switched Networks
Matthew Orlinski and Nick Filer
14:10 - 14:30 Predicting Human Contacts in Mobile Social Networks Using Supervised Learning
Kazem Jahanbakhsh, Valerie King and Gholamali C. Shoja

14:30 - 15:30 Keynote by Alain Barrat: "Dynamical Networks: from Measurements to Models"

15:30 - 16:00 Coffee Break

Session: Centrality

16:00 - 16:20 Distributed Assessment of the Closeness Centrality Ranking in Complex Networks
Klaus Wehmuth and Artur Ziviani
16:20 - 16:40 Robustness of Centrality Measures against Link Weight Quantization in Social Network Analysis
Yukihiro Matsumoto, Sho Tsugawa, Hiroyuki Ohsaki and Makoto Imase

16:40 - 17:00 Wrapping up