Researchers have defined the local complexity of a neural network with continuous piecewise linear activations as a measure of the density of linear regions over an input data distribution.
They have theoretically shown that ReLU networks learning low-dimensional feature representations have a lower local complexity.
This connects recent empirical observations on feature learning with concrete properties of the learned functions.
The local complexity also serves as an upper bound on the total variation of the function over the input data distribution, linking feature learning to adversarial robustness.
The researchers also consider how optimization drives ReLU networks towards solutions with lower local complexity, contributing a theoretical framework for understanding geometric properties of ReLU networks in relation to learning.