A Fast Algorithm for Finding k-Nearest Neighbors with Non-Metric Dissimilarity

  • Authors:
  • Bin Zhang;Sargur N. Srihari

  • Affiliations:
  • -;-

  • Venue:
  • IWFHR '02 Proceedings of the Eighth International Workshop on Frontiers in Handwriting Recognition (IWFHR'02)
  • Year:
  • 2002

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Abstract

Fast nearest neighbor (NN) finding has been extensively studied. While some fast NN algorithms using metrics rely on the essential properties of metric spaces, the others usingnon-metric measures fail for large-size templates. However, in some applications with very large size templates, the best performance is achieved by NN methods based on the dissimilaritymeasures resulting in a special space where computations cannot be pruned by the algorithms based-on the triangular inequality. For such NN methods, the existing fast algorithms except condensing algorithms are not applicable. In this paper, a fast hierarchical search algorithm is proposed to find k-NNs using a non-metric measure in a binary feature space. Experiments with handwritten digit recognition show that the new algorithm reduces on average dissimilarity computations by more than 90% while losing the accuracy by less than 0:1%, with a 10% increase in memory.