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Regularization for Unsupervised Classification on Taxonomies

  • Diego Sona
  • Sriharsha Veeramachaneni
  • Nicola Polettini
  • Paolo Avesani
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4203)

Abstract

We study unsupervised classification of text documents into a taxonomy of concepts annotated by only a few keywords. Our central claim is that the structure of the taxonomy encapsulates background knowledge that can be exploited to improve classification accuracy. Under our hierarchical Dirichlet generative model for the document corpus, we show that the unsupervised classification algorithm provides robust estimates of the classification parameters by performing regularization, and that our algorithm can be interpreted as a regularized EM algorithm. We also propose a technique for the automatic choice of the regularization parameter. In addition we propose a regularization scheme for K-means for hierarchies. We experimentally demonstrate that both our regularized clustering algorithms achieve a higher classification accuracy over simple models like minimum distance, Naïve Bayes, EM and K-means.

Keywords

Parameter Vector Regularization Parameter Regularization Scheme Reference Vector Unsupervised Classification 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Diego Sona
    • 1
  • Sriharsha Veeramachaneni
    • 1
  • Nicola Polettini
    • 1
  • Paolo Avesani
    • 1
  1. 1.ITC-IRSTPovo – TrentoItaly

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