Kenth Engø-Monsen

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In this paper we introduce a model for analyzing the spread of epidemics in a disconnected mobile network. The work is based on an extension, to a dynamic setting, of the eigenvector centrality principle introduced by two of the authors for the case of static networks. The extension builds on a new definition of <i>connectivity matrix</i> for a highly(More)
To understand the diffusive spreading of a product in a telecom network, whether the product is a service, handset, or subscription, it can be very useful to study the structure of the underlying social network. By combining mobile traffic data and product adoption history from one of Telenor&#x02019;s markets, we can define and measure an adoption(More)
The dominant eigenvector of matrices defined by weighted links in overlay networks plays an important role in many peer-to-peer applications. Examples include trust management, importance ranking to support search, and virtual coordinate systems to facilitate managing network proximity. Robust and efficient asynchronous distributed algorithms are known only(More)
The recent emergence of dengue viruses into new susceptible human populations throughout Asia and the Middle East, driven in part by human travel on both local and global scales, represents a significant global health risk, particularly in areas with changing climatic suitability for the mosquito vector. In Pakistan, dengue has been endemic for decades in(More)
Methods for link analysis are a key component in search engines for hyperlinked document networks. Documents are assigned an importance score based on the graph structure of the hyperlinks among the documents. At the heart of link analysis protocols we find the problem of calculating the principal eigenvector of a suitable matrix that is defined based on(More)
By combining mobile traffic data and product adoption history from one of the markets of the telecom provider Telenor, we define and measure an adoption network—roughly, the social network among adopters. We study and compare the evolution of this adoption network over time for several products – the iPhone handset, the Doro handset, the iPad 3G and(More)
We describe a model of computer security that applies results from the statistical properties of graphs to human-computer systems. The model attempts to determine a safe threshold of interconnectivity in a human-computer system by ad hoc network analyses. The results can be applied to physical networks, social networks and networks of clues in a forensic(More)
In this paper we apply geometric integrators of the RKMK type to the problem of integrating Lie– Poisson systems numerically. By using the coadjoint action of the Lie group G on the dual Lie algebra g∗ to advance the numerical flow, we devise methods of arbitrary order that automatically stay on the coadjoint orbits. First integrals known as Casimirs are(More)
We study the properties of the principal eigenvector for the adjacency matrix (and related matrices) for a general directed graph. In particular—motivated by the use of the eigenvector for estimating the “importance” of the nodes in the graph—we focus on the distribution of positive weight in this eigenvector, and give a coherent picture which builds upon(More)