Probabilistic Models Based on the Π-Sigmoid Distribution

  • Authors:
  • Anastasios Alivanoglou;Aristidis Likas

  • Affiliations:
  • Department of Computer Science, University of Ioannina, Ioannina, Greece GR 45110;Department of Computer Science, University of Ioannina, Ioannina, Greece GR 45110

  • Venue:
  • ANNPR '08 Proceedings of the 3rd IAPR workshop on Artificial Neural Networks in Pattern Recognition
  • Year:
  • 2008

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Abstract

Mixture models constitute a popular type of probabilistic neuralnetworks which model the density of a dataset using a convexcombination of statistical distributions, with the Gaussiandistribution being the one most commonly used. In this work wepropose a new probability density function, called theΠ-sigmoid, from its ability to form the shape of the letter"Π" by appropriately combining two sigmoid functions. Wedemonstrate its modeling properties and the different shapes thatcan take for particular values of its parameters. We then presentthe Π-sigmoid mixture model and propose a maximum likelihoodestimation method to estimate the parameters of such a mixturemodel using the Generalized Expectation Maximization algorithm. Weassess the performance of the proposed method using syntheticdatasets and also on image segmentation and illustrate itssuperiority over Gaussian mixture models.