Predicting the outputs of finite deep neural networks trained with noisy gradients

Gadi Naveh*, Oded Ben David, Haim Sompolinsky, Zohar Ringel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

A recent line of works studied wide deep neural networks (DNNs) by approximating them as Gaussian processes (GPs). A DNN trained with gradient flow was shown to map to a GP governed by the neural tangent kernel (NTK), whereas earlier works showed that a DNN with an i.i.d. prior over its weights maps to the so-called neural network Gaussian process (NNGP). Here we consider a DNN training protocol, involving noise, weight decay, and finite width, whose outcome corresponds to a certain non-Gaussian stochastic process. An analytical framework is then introduced to analyze this non-Gaussian process, whose deviation from a GP is controlled by the finite width. Our contribution is threefold: (i) In the infinite width limit, we establish a correspondence between DNNs trained with noisy gradients and the NNGP, not the NTK. (ii) We provide a general analytical form for the finite width correction (FWC) for DNNs with arbitrary activation functions and depth and use it to predict the outputs of empirical finite networks with high accuracy. Analyzing the FWC behavior as a function of n, the training set size, we find that it is negligible for both the very small n regime, and, surprisingly, for the large n regime [where the GP error scales as O(1/n)]. (iii) We flesh out algebraically how these FWCs can improve the performance of finite convolutional neural networks (CNNs) relative to their GP counterparts on image classification tasks.

Original languageAmerican English
Article number064301
JournalPhysical Review E
Volume104
Issue number6
DOIs
StatePublished - Dec 2021

Bibliographical note

Publisher Copyright:
© 2021 American Physical Society.

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