arXiv Machine Learning

Cost-Aware Stopping for Freeze-Thaw Bayesian Optimization: When Does One-Step Lookahead Suffice?

The paper introduces a cost‑aware stopping rule for Freeze‑Thaw Bayesian Optimization called EI stopping, which uses a one‑step lookahead to decide whether to continue evaluating a candidate. EI stopping compares the expected improvement of the next increment to its cost and stops when no improvement exceeds the cost, guaranteeing that it never performs worse than stopping immediately. The authors provide a theoretical certificate that identifies when EI stopping is premature and show through experiments that EI stopping performs comparably to a two‑step lookahead correction in high‑cost scenarios, while the correction outperforms EI stopping at low costs.

arXiv AI
Jun 29

When Is an LLM Worth It for Hyperparameter Optimization? A Budget-Matched Study on Tabular Data Finds the Warm-Start Is a Default Configuration, Not the Model

arXiv:2606. 21641v2 Announce Type: replace-cross Abstract: Large language models (LLMs) have been proposed as hyperparameter-optimization (HPO) advisors that "warm-start" search from prior knowledge, proposing strong configurations in very few evaluations.

By Carson Rodrigues, Oysturn Vas, Isaiah Abner DCosta, Nithish Kumar Prabhakaran
arXiv Machine Learning
Oct 23

Same Beliefs, Different Policies: Learning Reusable Representations for Early Stopping in LLM Reasoning

The paper introduces BELT (BELief-based Termination), a method that decouples outcome prediction from stopping control in large language models (LLMs). BELT learns beliefs about current and future answers from a frozen LLM’s hidden states and applies a linear stopping policy, enabling a single probe to adapt to various token‑price trade‑offs without retraining. Across five out‑of‑distribution math benchmarks, BELT cuts token usage by up to 51% while maintaining accuracy, and its lightweight probe outperforms stronger baselines in both efficiency and parameter count, also transferring effectively to coding and agentic tasks.

By Jingwei Ni, Dmitry Abulkhanov, Vladislav Smirnov, Markus Leippold, Elliott Ash, Timothy Baldwin, Artem Shelmanov, Mrinmaya Sachan
arXiv Machine Learning
Sep 14

Satisficing Regret Minimization in Bandits: Constant Rate and Light-Tailed Distribution

The paper introduces SELECT, an algorithmic framework for satisficing regret minimization in bandit problems, achieving constant expected satisficing regret when a satisficing arm exists. A variant, SELECT‑LITE, further ensures a light‑tailed satisficing regret distribution while maintaining constant expected regret in the realizable case and sub‑linear standard regret otherwise. Experiments on synthetic data and a real‑world dynamic pricing scenario demonstrate the practical effectiveness of both algorithms.

By Qing Feng, Tianyi Ma, Ruihao Zhu
arXiv Statistics ML
Oct 28

Confidence Is Not a Promise: A Reference Audit of Typed Decision Models

The paper evaluates how well typed decision models, which output probability distributions, actually provide reliable guarantees. By comparing open-weight Laya and Jev 1.13 across 190 evaluations, the study finds that point‑estimate thresholds frequently break promised accuracy, while a Beta lower‑bound rule and Learn‑then‑Test approach maintain guarantees more consistently. The work also explores calibration across languages, the impact of noise, data requirements for fine‑tuning, and the limitations of confidence in predicting outcomes or providing faithful explanations.

By Pedro Carvalho Brom