Parameter-free Dynamic Regret: Time-varying Movement Costs, Delayed Feedback, and Memory

Fuente: arXiv
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Main Authors: Qiu, Hao, Jacobsen, Andrew, Esposito, Emmanuel, Zhang, Mengxiao
Format: Preprint
Published: 2026
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author Qiu, Hao
Jacobsen, Andrew
Esposito, Emmanuel
Zhang, Mengxiao
author_facet Qiu, Hao
Jacobsen, Andrew
Esposito, Emmanuel
Zhang, Mengxiao
contents In this paper, we study dynamic regret in unconstrained online convex optimization (OCO) with movement costs. Specifically, we generalize the standard setting by allowing the movement cost coefficients $λ_t$ to vary arbitrarily over time. Our main contribution is a novel algorithm that establishes the first comparator-adaptive dynamic regret bound for this setting, guaranteeing $\widetilde{\mathcal{O}}(\sqrt{(M^2+MP_T)(T+\sum_t λ_t)})$ regret, where $P_T$ is the path length of the comparator sequence over $T$ rounds and $M$ is the maximal comparator norm. Our result recovers the optimal adaptive rates for both static and dynamic regret in OCO as the special case where $λ_t=0$ for all rounds. To demonstrate the versatility of our results, we consider two applications: OCO with delayed feedback and OCO with time-varying memory. We show that both problems can be translated into time-varying movement costs, establishing a novel reduction specifically for the delayed feedback setting that is of independent interest. A crucial observation is that the first-order dependence on movement costs in our regret bound plays a key role in enabling optimal comparator-adaptive dynamic regret guarantees in both settings.
format Preprint
id arxiv_https___arxiv_org_abs_2602_06902
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Parameter-free Dynamic Regret: Time-varying Movement Costs, Delayed Feedback, and Memory
Qiu, Hao
Jacobsen, Andrew
Esposito, Emmanuel
Zhang, Mengxiao
Machine Learning
In this paper, we study dynamic regret in unconstrained online convex optimization (OCO) with movement costs. Specifically, we generalize the standard setting by allowing the movement cost coefficients $λ_t$ to vary arbitrarily over time. Our main contribution is a novel algorithm that establishes the first comparator-adaptive dynamic regret bound for this setting, guaranteeing $\widetilde{\mathcal{O}}(\sqrt{(M^2+MP_T)(T+\sum_t λ_t)})$ regret, where $P_T$ is the path length of the comparator sequence over $T$ rounds and $M$ is the maximal comparator norm. Our result recovers the optimal adaptive rates for both static and dynamic regret in OCO as the special case where $λ_t=0$ for all rounds. To demonstrate the versatility of our results, we consider two applications: OCO with delayed feedback and OCO with time-varying memory. We show that both problems can be translated into time-varying movement costs, establishing a novel reduction specifically for the delayed feedback setting that is of independent interest. A crucial observation is that the first-order dependence on movement costs in our regret bound plays a key role in enabling optimal comparator-adaptive dynamic regret guarantees in both settings.
title Parameter-free Dynamic Regret: Time-varying Movement Costs, Delayed Feedback, and Memory
topic Machine Learning
url https://arxiv.org/abs/2602.06902