On the Limitations of General Purpose Domain Generalisation Methods

Fuente: arXiv
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Hauptverfasser: Gouk, Henry, Bohdal, Ondrej, Li, Da, Hospedales, Timothy
Format: Preprint
Veröffentlicht: 2022
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author Gouk, Henry
Bohdal, Ondrej
Li, Da
Hospedales, Timothy
author_facet Gouk, Henry
Bohdal, Ondrej
Li, Da
Hospedales, Timothy
contents We investigate the fundamental performance limitations of learning algorithms in several Domain Generalisation (DG) settings. Motivated by the difficulty with which previously proposed methods have in reliably outperforming Empirical Risk Minimisation (ERM), we derive upper bounds on the excess risk of ERM, and lower bounds on the minimax excess risk. Our findings show that in all the DG settings we consider, it is not possible to significantly outperform ERM. Our conclusions are limited not only to the standard covariate shift setting, but also two other settings with additional restrictions on how domains can differ. The first constrains all domains to have a non-trivial bound on pairwise distances, as measured by a broad class of integral probability metrics. The second alternate setting considers a restricted class of DG problems where all domains have the same underlying support. Our analysis also suggests how different strategies can be used to optimise the performance of ERM in each of these DG setting. We also experimentally explore hypotheses suggested by our theoretical analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2202_00563
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle On the Limitations of General Purpose Domain Generalisation Methods
Gouk, Henry
Bohdal, Ondrej
Li, Da
Hospedales, Timothy
Machine Learning
We investigate the fundamental performance limitations of learning algorithms in several Domain Generalisation (DG) settings. Motivated by the difficulty with which previously proposed methods have in reliably outperforming Empirical Risk Minimisation (ERM), we derive upper bounds on the excess risk of ERM, and lower bounds on the minimax excess risk. Our findings show that in all the DG settings we consider, it is not possible to significantly outperform ERM. Our conclusions are limited not only to the standard covariate shift setting, but also two other settings with additional restrictions on how domains can differ. The first constrains all domains to have a non-trivial bound on pairwise distances, as measured by a broad class of integral probability metrics. The second alternate setting considers a restricted class of DG problems where all domains have the same underlying support. Our analysis also suggests how different strategies can be used to optimise the performance of ERM in each of these DG setting. We also experimentally explore hypotheses suggested by our theoretical analysis.
title On the Limitations of General Purpose Domain Generalisation Methods
topic Machine Learning
url https://arxiv.org/abs/2202.00563