2019

Complexity of Linear Regions in Deep Networks

Hanin, Boris, Rolnick, David

Understand

It is well-known that the expressivity of a neural network depends on its architecture, with deeper networks expressing more complex functions.

  • In the case of networks that compute piecewise linear functions, such as those with ReLU activation, the number of distinct linear regions is a natural measure of expressivity.
  • It is possible to construct networks with merely a single region, or for which the number of linear regions grows exponentially with depth; it is not clear where within this range most networks fall in practice, either before or after training.
  • In this paper, we provide a mathematical framework to count the number of linear regions of a piecewise linear network and measure the volume of the boundaries between these regions.

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