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[Author] Seungjin CHOI(2hit)

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  • Natural Gradient Learning for Spatio-Temporal Decorrelation: Recurrent Network

    Seungjin CHOI  Shunichi AMARI  Andrzej CICHOCKI  

     
    PAPER-Neural Networks and Bioengineering

      Vol:
    E83-A No:12
      Page(s):
    2715-2722

    Spatio-temporal decorrelation is the task of eliminating correlations between associated signals in spatial domain as well as in time domain. In this paper, we present a simple but efficient adaptive algorithm for spatio-temporal decorrelation. For the task of spatio-temporal decorrelation, we consider a dynamic recurrent network and calculate the associated natural gradient for the minimization of an appropriate optimization function. The natural gradient based spatio-temporal decorrelation algorithm is applied to the task of blind deconvolution of linear single input multiple output (SIMO) system and its performance is compared to the spatio-temporal anti-Hebbian learning rule.

  • Approximate Maximum Likelihood Source Separation Using the Natural Gradient

    Seungjin CHOI  Andrzej CICHOCKI  Liqing ZHANG  Shun-ichi AMARI  

     
    PAPER-Digital Signal Processing

      Vol:
    E86-A No:1
      Page(s):
    198-205

    This paper addresses a maximum likelihood method for source separation in the case of overdetermined mixtures corrupted by additive white Gaussian noise. We consider an approximate likelihood which is based on the Laplace approximation and develop a natural gradient adaptation algorithm to find a local maximum of the corresponding approximate likelihood. We present a detailed mathematical derivation of the algorithm using the Lie group invariance. Useful behavior of the algorithm is verified by numerical experiments.