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Decay Models

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Encyclopedia of Database Systems

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Definition

Decay models are applicable on data sets where data items are associated with points in a metric space (locations) and there is a notion of “significance” of a data item to a location, which decays (decreases) with the distance between the item and the location. This decrease is modeled by a decay function.

Each location has a “view” of the data set through a different weight distribution over the items: the weight associated with each item is its decayed weight which is a product of its original weight and a decay function applied to its distance from the observing location.

While global aggregates or statistics are computed over the set of items and their original weights, decaying aggregates or decaying statistics depend on the location with respect to which the aggregation is performed and on the decay function. Figure 1 illustrates a small network and the decaying sum with respect to all nodes.

Decay Models. Figure 1
figure 1_126

Decaying sum over a network with respect to decay...

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Authors and Affiliations

  1. AT&T Labs-Research, Florham Park, NJ, USA

    Edith Cohen

Authors
  1. Edith Cohen
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Editors and Affiliations

  1. College of Computing, Georgia Institute of Technology, 266 Ferst Drive, 30332-0765, Atlanta, GA, USA

    LING LIU (Professor) (Professor)

  2. Database Research Group David R. Cheriton School of Computer Science, University of Waterloo, 200 University Avenue West, N2L 3G1, Waterloo, ON, Canada

    M. TAMER ÖZSU (Professor and Director, University Research Chair) (Professor and Director, University Research Chair)

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Cohen, E. (2009). Decay Models. In: LIU, L., ÖZSU, M.T. (eds) Encyclopedia of Database Systems. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-39940-9_126

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