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A Spectral Condition for Feature Learning

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arxiv 2310.17813 v2 pith:KP2GUVDW submitted 2023-10-26 cs.LG

A Spectral Condition for Feature Learning

classification cs.LG
keywords featurelearningspectralnetworknetworksneuralnormscaling
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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The push to train ever larger neural networks has motivated the study of initialization and training at large network width. A key challenge is to scale training so that a network's internal representations evolve nontrivially at all widths, a process known as feature learning. Here, we show that feature learning is achieved by scaling the spectral norm of weight matrices and their updates like $\sqrt{\texttt{fan-out}/\texttt{fan-in}}$, in contrast to widely used but heuristic scalings based on Frobenius norm and entry size. Our spectral scaling analysis also leads to an elementary derivation of \emph{maximal update parametrization}. All in all, we aim to provide the reader with a solid conceptual understanding of feature learning in neural networks.

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