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A complex network can be modeled as a graph representing the ''who knows who " relationship. In the context of graph theory for social networks, the notion of centrality is used to assess the relative importance of nodes in a given network topology. For example, in a network composed of large dense clusters connected through only a few links, the nodes(More)
In this paper, we report our advances, choices and first insights in the design of a mobile phone powered data collection platform. We believe that collecting such data is vital to achieve a better understanding/modeling of several phe-nomenons related to human activity (e.g. mobility, social contacts, or terminal failures). However, designing such a(More)
Gossip-based communication protocols are often touted as being robust. Not surprisingly, such a claim relies on assumptions under which gossip protocols are supposed to operate. In this paper, we discuss and in some cases expose some of these assumptions and discuss how sensitive the robustness of gossip is to these assumptions. This analysis gives rise to(More)
The increase of interest in the analysis of contemporary social networks, for both academic and economic reasons, has highlighted the inherent difficulties in handling large and complex structures. Among the tools provided by researchers for network analysis, the centrality notion, capturing the importance of individuals in a graph, is of particular(More)
Traceroute measurements are one of the main instruments to shed light onto the structure and properties of today’s complex networks such as the Internet. This article studies the feasibility and infeasibility of inferring the network topology given traceroute data from a worst-case perspective, i.e., without any probabilistic assumptions on, e.g., the(More)
This paper considers the problem of electing an eventual leader in an asyn-chronous shared memory system. While this problem has received a lot of attention in message-passing systems, very few solutions have been proposed for shared memory systems. As an eventual leader cannot be elected in a pure asynchronous system prone to process crashes, the paper(More)
This paper tackles the consensus problem in asynchronous systems prone to byzantine failures. One way to circumvent the FLP impossibility result consists in adding synchrony assumptions (deterministic solution). In the context of crash failures (at most t processes may crash), the weakest partially synchronous system model assumes at least one correct(More)
In many large scale distributed systems and on the web, agents need to interact with other unknown agents to carry out some tasks or transactions. The ability to reason about and assess the potential risks in carrying out such transactions is essential for providing a safe and reliable environment. A traditional approach to reason about the trustworthi-ness(More)
—This paper demonstrates that virtual networks that are dynamically embedded on a given resource network may constitute a security threat as properties of the infrastructure—typically a business secret—are disclosed. We initiate the study of this new problem and introduce the notion of request complexity which captures the number of virtual network(More)