Agile Online Model Selection: Resolving Adaptation Lag via Safeguarded Large Learning Rates
- URL: http://arxiv.org/abs/2605.26919v2
- Date: Mon, 01 Jun 2026 03:05:51 GMT
- Title: Agile Online Model Selection: Resolving Adaptation Lag via Safeguarded Large Learning Rates
- Abstract summary: We propose a novel optimistic online mirror descent that utilizes safeguarded large learning rates up to $(T)$.<n>Our key technical contribution is a post-hoc penalty mechanism that dynamically monitors unstable updates and excludes learning rates incurring excessive regret.<n> Empirical evaluations on three synthetic and eleven diverse real-world datasets demonstrate that our approach reduces the adaptation lag from hundreds of rounds to a few rounds.
- Score: 9.463718838347955
- License: http://creativecommons.org/licenses/by-nc-nd/4.0/
- Abstract: Maintaining predictive accuracy in non-stationary environments requires online model selection to adapt autonomously to unknown distribution shifts. However, existing tuning-free algorithms face a fundamental trade-off between robustness and agility. Specifically, to ensure dynamic regret bounds, they must restrict learning rates to small constants (e.g., $O(1)$). This restriction inevitably causes significant adaptation lag during abrupt changes. To resolve this, we propose a novel optimistic online mirror descent that utilizes safeguarded large learning rates up to $Θ(T)$, where $T$ is the number of rounds. Our key technical contribution is a post-hoc penalty mechanism that dynamically monitors unstable updates and excludes learning rates incurring excessive regret, eliminating the need for restrictive a priori constraints. We show that the cumulative penalty remains $O(\log T)$, allowing our algorithm to match near-optimal worst-case guarantees while achieving superior rates in benign cases. Empirical evaluations on three synthetic and eleven diverse real-world datasets demonstrate that our approach reduces the adaptation lag from hundreds of rounds to a few rounds, consistently outperforming tuning-free baselines.
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