Puzzling Success of Overparameterization: Lottery Tickets or Escape Dimensions?
The paper investigates why overparameterized neural networks generalize well, proposing that overparameterization creates "escape dimensions" that help gradient descent find good solutions, contrasting with the lottery ticket hypothesis.
Background
- This is an EPFL research paper (a Swiss technical university) about why overparameterized neural networks — models with far more parameters than training data points — often generalize better, not worse, than smaller models. This contradicts classical statistical wisdom.
- "Lottery ticket hypothesis" is a prominent theory: large networks work because they contain a small lucky "winning" subnetwork that does the actual learning. This paper argues that's not the full story.
- "Escape dimensions" is the authors' alternative concept: extra parameters create new directions in the model's optimization landscape that help gradient descent escape bad local minima and find flatter, more generalizable solutions.
- The work uses mathematical analysis on simplified models (two-layer ReLU networks) to compare these two explanations systematically. It speaks to a live debate in deep learning theory about why "bigger is better" actually works.