arXiv Machine Learning

Dynamic Regret in Online Convex Optimization with Indicator Switching Costs

arXiv:2609. 30556v1 Announce Type: new Abstract: We study dynamic regret in online convex optimization with an \emph{indicator switching cost}: a fixed penalty incurred whenever two consecutive decisions differ.

arXiv Machine Learning
Sep 21

From Switching to Dynamic Regret: A Simple Reduction via Unbiased Random Sequences

The paper introduces a straightforward framework that transforms dynamic regret minimization into switching regret minimization by constructing an unbiased random sequence for any comparator sequence. Using this reduction, the authors derive dynamic regret bounds for strongly convex and exp-concave losses of “~O(T^{1/3}P_T^{2/3})” and for general convex losses of “O(√{T(1+P_T)})”, matching known minimax optimal results. The approach leverages off-the-shelf switching regret algorithms and controlled variance to achieve these bounds.

By Yibo Wang, Wenhao Yang, Sifan Yang, Yuanyu Wan, Lijun Zhang
arXiv AI
Sep 2

Bandits in Prod: Hyperparameter Optimization at Inference Time

The paper introduces Online Hyperparameter Optimization (OHPO), framing it as an infinitely many‑armed bandit problem over mixed and conditional search spaces. It proposes the IMABO framework, which couples any bandit policy with any oracle for proposing new configurations, and presents IMOSS—a restart‑free anytime policy with provable regret bounds. Experiments show that IMABO, combined with practical oracles such as TPE, an incumbent‑mutation oracle, and a pretrained tabular foundation model, outperforms random search across a range of settings from classical ML models to LLM‑based agents.

By Louis Abraham, Tuan-Anh Nguyen, Nicolas Devatine
arXiv AI
Sep 2

Drift-Aware LLM Routing with Sparse Contexts and Shared Budgets

The paper introduces Drift‑Aware Sparse Routing (DRS), a method for routing requests in a multi‑model language service while respecting compute, latency, memory, or cost budgets. DRS estimates reward and resource use from a rolling audit window, routes using pessimistic reward and optimistic cost estimates, updates resource shadow prices online, and applies a hard meter before commitment. The authors provide theoretical regret bounds that separate control from statistics, showing how the method adapts to non‑stationary prompt distributions and model changes.

By Cheung Hao Lee, Patrick Wong