• When & Where: Seminars are generally (please, check the timeline and location before coming!) held on:
    • Wednesday afternoon at LINCS (14h-15h, Salle de Conseil) and
    • Thursday afternoon at Barrault (14h-15h, Amphi Saphir).
  • Contact us: if you wish to give a talk on networking, math, software or embedded-system topics, do not hesitate to contact us

[Next talks] [All talks]

04/10/2016 (@Barrault, Amphi B312)Ricardo Baeza-Yates (CTO, NTENT)Data and Algorithmic Bias in the Web
05/10/2016 (@LINCS, Seminar Room)Emilio Leonardi (Politecnico di Torino)Generalized Threshold-Based Epidemics in Random Graphs: the Power of Extreme Values
12/10/2016 (@LINCS, Seminar Room)Vaggelis G. Douros (Orange Labs)Caching Games between Content Providers and Internet Service Providers
09/11/2016 (@LINCS, Seminar Room)Marwan Fayed (University of Stirling)TBD

Date:04/10/2016, 11h
Room:Barrault, Amphi B312
Speaker:Ricardo Baeza-Yates (CTO, NTENT)
Talk:Data and Algorithmic Bias in the Web
Abstract:The Web is the largest public big data repository that humankind hascreated. In this overwhelming data ocean, we need to be aware of thequality and, in particular, of the biases that exist in this data. Inthe Web, biases also come from redundancy and spam, as well as fromalgorithms that we design to improve the user experience. This problemis further exacerbated by biases that are added by these algorithms,specially in the context of search and recommendation systems. Theyinclude selection and presentation bias in many forms, interaction bias,social bias, etc. We give several examples and their relation to sparsityand privacy, stressing the importance of the user context to avoid thesebiases.
Biography:Ricardo Baeza-Yates areas of expertise are web search and data mining,information retrieval, data science and algorithms. He is CTO of NTENT, a semantic search technology company. Before he was VP of Research at Yahoo Labs, based in Barcelona, Spain, and later in Sunnyvale, California, from January 2006 to February 2016. He also is part time Professor at DTIC of the Universitat Pompeu Fabra, in Barcelona, Spain, as well as at DCC of Universidad de Chile in Santiago. Until 2004 he was Professor and founding director of the Center for Web Research at the later place. He obtained a Ph.D. in CS from the University of Waterloo, Canada, in 1989. He is co-author of the best-seller Modern Information Retrieval textbook published by Addison-Wesley in 2011 (2nd ed), that won the ASIST 2012 Book of the Year award. From 2002 to 2004 he was elected to the board of governors of the IEEE Computer Society and in 2012 he was elected for the ACM Council. Since 2010 is a founding member of the Chilean Academy of Engineering. In 2009 he was named ACM Fellow and in 2011 IEEE Fellow, among other awards and distinctions.
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Date:05/10/2016, 14h
Room:LINCS, Seminar Room
Speaker:Emilio Leonardi (Politecnico di Torino)
Talk:Generalized Threshold-Based Epidemics in Random Graphs: the Power of Extreme Values
Abstract:Bootstrap percolation is a well-known activation process in a graph,in which a node becomes active when it has at least $r$ active neighbors.Such process, originally studied on regular structures, has been recentlyinvestigated also in the context of random graphs, where it can serve as a simplemodel for a wide variety of cascades, such as thespreading of ideas, trends, viral contents, etc. over large social networks.In particular, it has been shown that in $G(n,p)$ the final active setcan exhibit a phase transition for a sub-linear number of seeds.In this paper, we propose a unique framework to study similarsub-linear phase transitions for a much broader class of graph modelsand epidemic processes. Specifically, we consider i) a generalized versionof bootstrap percolation in $G(n,p)$ with random activation thresholdsand random node-to-node influences; ii) different random graph models,including graphs with given degree sequence and graphs withcommunity structure (block model). The common thread of our work is toshow the surprising sensitivity of the critical seed set sizeto extreme values of distributions, which makes some systems dramaticallyvulnerable to large-scale outbreaks. We validate our results running simulation onboth synthetic and real graphs. Joint work with M. Garetto and G. Torrisi, appeared at ACM SIGMETRIC 2016.
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Date:12/10/2016, 14h
Room:LINCS, Seminar Room
Speaker:Vaggelis G. Douros (Orange Labs)
Talk:Caching Games between Content Providers and Internet Service Providers
Abstract:We consider a scenario where an Internet Service Provider (ISP) serves users that choose digital content among M Content Providers (CP). In the status quo, these users pay both access fees to the ISP and content fees to each chosen CP; however, neither the ISP nor the CPs share their profit. We revisit this model by introducing a different business model where the ISP and the CP may have motivation to collaborate in the framework of caching. The key idea is that the ISP deploys a cache for a CP provided that they share both the deployment cost and the additional profit that arises due to caching. Under the prism of coalitional games, our contributions include the application of the Shapley value for a fair splitting of the profit, the stability analysis of the coalition and the derivation of closed-form formulas for the optimal caching policy.Our model captures not only the case of non-overlapping contents among the CPs, but also the more challenging case of overlapping contents; for the latter case, a non-cooperative game among the CPs is introduced and analyzed to capture the negative externality on the demand of a particular CP when caches for other CPs are deployed.Joint work with S. Elayoubi, E. Altman, and Y. Hayel to be presented at the 10th EAI International Conference on Performance Evaluation Methodologies and Tools (Valuetools 2016). The full version of the paper has been selected to be published in a special issue of the Elsevier journal of Performance Evaluation (PEVA).
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Date:09/11/2016, 14h
Room:LINCS, Seminar Room
Speaker:Marwan Fayed (University of Stirling)
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