Using unlabeled data for learning classification problems

  • Authors:
  • A. Verikas;A. Gelzinis;K. Malmqvist

  • Affiliations:
  • Kaunas Univ. of Technology, Kaunas, Lithuania;Kaunas Univ. of Technology, Kaunas, Lithuania;Halmstad Univ., Halmstad, Sweden

  • Venue:
  • New learning paradigms in soft computing
  • Year:
  • 2002

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Abstract

This chapter presents an approach of using unlabeled data for learning classification problems. The chapter consists of two parts. In the first part of the chapter, an approach of using both labeled and unlabeled data to train a multilayer percetron is presented. The approach banks on the assumption that regions of low pattern density usually separate data classes. The unlabeled data are iteratively preprocessed by a perceptron being trained to obtain the soft class label estimates. It is demonstrated that substantial gains in classification performance may be achieved by using the approach when the labeled data do not adequately represent the entire class distributions. In the second part of the chapter, we propose a quality function for learning decision boundary between data clusters from unlabeled data. The function is based on third order polynomials. The objective of the quality function is to find a place in the input sparse in data points. By maximizing the quality function, we find a decision boundary between data clusters. A superiority of the proposed quality function over the other similar functions as well as the conventional clustering algorithms tested has been observed in the experiments.