Are Greedy Task Orderings Better Than Random in Continual Linear Regression?

Fuente: arXiv
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Main Authors: Tsipory, Matan, Levinstein, Ran, Evron, Itay, Kong, Mark, Needell, Deanna, Soudry, Daniel
Format: Preprint
Published: 2025
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author Tsipory, Matan
Levinstein, Ran
Evron, Itay
Kong, Mark
Needell, Deanna
Soudry, Daniel
author_facet Tsipory, Matan
Levinstein, Ran
Evron, Itay
Kong, Mark
Needell, Deanna
Soudry, Daniel
contents We analyze task orderings in continual learning for linear regression, assuming joint realizability of training data. We focus on orderings that greedily maximize dissimilarity between consecutive tasks, a concept briefly explored in prior work but still surrounded by open questions. Using tools from the Kaczmarz method literature, we formalize such orderings and develop geometric and algebraic intuitions around them. Empirically, we demonstrate that greedy orderings converge faster than random ones in terms of the average loss across tasks, both for linear regression with random data and for linear probing on CIFAR-100 classification tasks. Analytically, in a high-rank regression setting, we prove a loss bound for greedy orderings analogous to that of random ones. However, under general rank, we establish a repetition-dependent separation. Specifically, while prior work showed that for random orderings, with or without replacement, the average loss after $k$ iterations is bounded by $\mathcal{O}(1/\sqrt{k})$, we prove that single-pass greedy orderings may fail catastrophically, whereas those allowing repetition converge at rate $\mathcal{O}(1/\sqrt[3]{k})$. Overall, we reveal nuances within and between greedy and random orderings.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19941
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Are Greedy Task Orderings Better Than Random in Continual Linear Regression?
Tsipory, Matan
Levinstein, Ran
Evron, Itay
Kong, Mark
Needell, Deanna
Soudry, Daniel
Machine Learning
We analyze task orderings in continual learning for linear regression, assuming joint realizability of training data. We focus on orderings that greedily maximize dissimilarity between consecutive tasks, a concept briefly explored in prior work but still surrounded by open questions. Using tools from the Kaczmarz method literature, we formalize such orderings and develop geometric and algebraic intuitions around them. Empirically, we demonstrate that greedy orderings converge faster than random ones in terms of the average loss across tasks, both for linear regression with random data and for linear probing on CIFAR-100 classification tasks. Analytically, in a high-rank regression setting, we prove a loss bound for greedy orderings analogous to that of random ones. However, under general rank, we establish a repetition-dependent separation. Specifically, while prior work showed that for random orderings, with or without replacement, the average loss after $k$ iterations is bounded by $\mathcal{O}(1/\sqrt{k})$, we prove that single-pass greedy orderings may fail catastrophically, whereas those allowing repetition converge at rate $\mathcal{O}(1/\sqrt[3]{k})$. Overall, we reveal nuances within and between greedy and random orderings.
title Are Greedy Task Orderings Better Than Random in Continual Linear Regression?
topic Machine Learning
url https://arxiv.org/abs/2510.19941