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                    Seminar Announcement

            School of Computer Science, CECS
             The Australian National University
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Date:  Thursday, 26 November 2009
Time:  11:00 am to 12:00 noon
Venue: Room N101, CSIT Building [108]


Speaker: Dr Rui Zhang 

Title:   The V*-Diagram, a Query Dependent Approach to Moving Nearest
	 Neighbor Queries


Abstract: 

  The moving k nearest neighbor (MkNN) query continuously finds the k
  nearest neighbors of a moving query point. MkNN queries can be
  efficiently processed through the use of safe regions. In general, a
  safe region is a region within which the query point can move without
  changing the query answer. This talk presents an incremental
  safe-region-based technique for answering MkNN queries, called the
  V*-Diagram, as well as analysis and evaluation of its associated
  algorithm, V*-kNN. Traditional safe-region approaches compute a safe
  region based on the data objects but independent of the query location.
  Our approach exploits the knowledge of the query location and the
  boundary of the search space in addition to the data objects. As a
  result, V*-kNN has much smaller I/O and computation costs than existing
  methods. We further provide cost models to estimate the number of data
  accesses for V*-kNN and a competitive technique, RIS-kNN. The V*-Diagram
  and V*-kNN are also applicable to the domain of spatial networks and we
  present algorithms to construct a spatial-network V*-Diagram. Our
  experimental study shows that V*-kNN significantly outperforms the
  competitive techniques and verifies the accuracy of the cost models. The
  results of this work are published in VLDB'08 conference and VLDB Journal.

Biography:

  Dr Rui Zhang is a lecturer at the Department of Computer Science and
  Software Engineering of the University of Melbourne. He got his PhD from
  National University of Singapore. His research interests include #
  indexing and query processing, Spatial and temporal data management,
  sequence data management, data streams, and cloud computing. He has
  published widely in top database conferences and serve as PC members on
  many of such conferences. Please see his website for more information:
  http://www.csse.unimelb.edu.au/~rui/


URL: http://cs.anu.edu.au/lib/seminars/seminars09/dept20091126a



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