Paris Descartes University Seminar Series on Data Analytics
in collaboration with the diNo group

Invited Seminar Talk

Building All k Nearest Neighbor Social Communities
Prof. Demetris Zeinalipour, Max Planck Institute for Informatics (Germany) & University of Cyprus (Cyprus)

when: 12 April 2017, 11:30am
where: room Turing Reunion, 7th floor, Paris Descartes University, 45 Rue Des Saints Peres, Paris 75006


A wide spectrum of Internet-scale mobile applications, ranging from social networking, gaming and entertainment to emergency response and crisis management, all require efficient and scalable All k Nearest Neighbor (AkNN) computations over millions of moving objects every few seconds to be operational. Most traditional techniques for computing AkNN queries are centralized, lacking both scalability and efficiency. Only recently, distributed techniques for shared-nothing cloud infrastructures have been proposed to achieve scalability for large datasets. These batch-oriented algorithms are sub-optimal due to inefficient data space partitioning and data replication among processing units. In this talk I will present Spitfire, a distributed algorithm that provides a scalable and high performance AkNN processing framework. The proposed algorithm deploys a fast load-balanced partitioning scheme along with an efficient replication-set selection algorithm, to provide fast main-memory computations of the exact AkNN results in a batch-oriented manner. I will also overview Rayzit, an experimental and open-source mobile AkNN service we established and operate that reached over 45,000 real user interactions to this date. My talk will conclude with a summary of other recent research related to Indoor Localization and Privacy (IEEE TKDE'15) as well as Telco Big Data (IEEE ICDE'17).

Short Bio

Demetris Zeinalipour is an Assistant Professor of Computer Science at the University of Cyprus, where he founded and directs the Data Management Systems Laboratory (DMSL). He holds a Ph.D. (2005) and M.Sc. (2003) in Computer Science and Engineering from the University of California - Riverside, CA, USA and a B.Sc. in Computer Science from the University of Cyprus (2000). Before his current appointment, he served the University of Cyprus and the Open University of Cyprus as a Lecturer of Computer Science. He has also been a short-term Visiting Researcher at the Network Intelligence Lab of Akamai Technologies, Cambridge, MA, USA (2004), a Marie-Curie Fellow at the University of Athens, Greece (2007) and a Visiting Researcher at the University of Pittsburgh, PA, USA (2015). During 2016-2017, he will be a Humboldt Fellow at the Max Planck Institute for Informatics, Saarbr├╝cken, Germany. His primary research interests include Data Management in Computer Systems and Networks, particularly Mobile and Sensor Data Management; Big Data Management in Parallel and Distributed Architectures; Spatio-Temporal Data Management; Network and Telco Data Management; Crowd, Web 2.0 and Indoor Data Management; Data Privacy Management. He is Distinguished Speaker of ACM (2017-2020), a Senior Member of ACM, a Senior Member of IEEE, and Member of USENIX. For more info visit:

Hosted by: Themis Palpanas

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