2019

Pathological spectra of the Fisher information metric and its variants in deep neural networks

Karakida, Ryo, Akaho, Shotaro, Amari, Shun-ichi

Understand

The Fisher information matrix (FIM) plays an essential role in statistics and machine learning as a Riemannian metric tensor or a component of the Hessian matrix of loss functions.

  • Focusing on the FIM and its variants in deep neural networks (DNNs), we reveal their characteristic scale dependence on the network width, depth and sample size when the network has random weights and is sufficiently wide.
  • This study covers two widely-used FIMs for regression with linear output and for classification with softmax output.
  • Both FIMs asymptotically show pathological eigenvalue spectra in the sense that a small number of eigenvalues become large outliers depending the width or sample size while the others are much smaller.

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