Flexible Infinite-Width Graph Convolutional Neural Networks

Fuente: arXiv
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Hauptverfasser: Anson, Ben, Milsom, Edward, Aitchison, Laurence
Format: Preprint
Veröffentlicht: 2024
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author Anson, Ben
Milsom, Edward
Aitchison, Laurence
author_facet Anson, Ben
Milsom, Edward
Aitchison, Laurence
contents A common theoretical approach to understanding neural networks is to take an infinite-width limit, at which point the outputs become Gaussian process (GP) distributed. This is known as a neural network Gaussian process (NNGP). However, the NNGP kernel is fixed and tunable only through a small number of hyperparameters, thus eliminating the possibility of representation learning. This contrasts with finite-width NNs, which are often believed to perform well because they are able to flexibly learn representations for the task at hand. Thus, in simplifying NNs to make them theoretically tractable, NNGPs may eliminate precisely what makes them work well (representation learning). This motivated us to understand whether representation learning is necessary in a range of graph tasks. We develop a precise tool for this task, the graph convolutional deep kernel machine. This is very similar to an NNGP, in that it is an infinite width limit and uses kernels, but comes with a ``knob'' to control the amount of flexibility and hence representation learning. We found that representation learning gives noticeable performance improvements for heterophilous node classification tasks, but less so for homophilous node classification tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06525
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Flexible Infinite-Width Graph Convolutional Neural Networks
Anson, Ben
Milsom, Edward
Aitchison, Laurence
Machine Learning
A common theoretical approach to understanding neural networks is to take an infinite-width limit, at which point the outputs become Gaussian process (GP) distributed. This is known as a neural network Gaussian process (NNGP). However, the NNGP kernel is fixed and tunable only through a small number of hyperparameters, thus eliminating the possibility of representation learning. This contrasts with finite-width NNs, which are often believed to perform well because they are able to flexibly learn representations for the task at hand. Thus, in simplifying NNs to make them theoretically tractable, NNGPs may eliminate precisely what makes them work well (representation learning). This motivated us to understand whether representation learning is necessary in a range of graph tasks. We develop a precise tool for this task, the graph convolutional deep kernel machine. This is very similar to an NNGP, in that it is an infinite width limit and uses kernels, but comes with a ``knob'' to control the amount of flexibility and hence representation learning. We found that representation learning gives noticeable performance improvements for heterophilous node classification tasks, but less so for homophilous node classification tasks.
title Flexible Infinite-Width Graph Convolutional Neural Networks
topic Machine Learning
url https://arxiv.org/abs/2402.06525