arXiv Machine Learning

Uniform Race: Parameter-Free Approximate Rejection Sampling

The paper introduces Uniform Race (UR), a parameter‑free algorithm for approximate rejection sampling that selects a sample by maximizing the ratio of its importance weight to an independent uniform random variable. UR achieves the same total variation error bound as the optimal rejection sampler that requires knowledge of the best acceptance threshold, and it outperforms both the budget‑calibrated rejection sampler and sampling importance resampling in certain settings. The authors also provide theoretical conditions under which UR’s selection probabilities are uniquely optimal and validate the method on large‑language‑model reasoning tasks.

arXiv AI
Jun 11

The Power of Test-Time Training for Approximate Sampling

arXiv:2606. 11437v1 Announce Type: cross Abstract: Efficiently sampling from a complex probability distribution is a fundamental problem which has become increasingly pertinent in recent years with the rise of generative AI, as sophisticated sampling procedures from LLMs have been proposed to solve challenging reasoning problems.

By Noah Golowich, Ankur Moitra, Dhruv Rohatgi
arXiv Machine Learning
Jun 18

How fast can you find a good hypothesis?

arXiv:2509. 03734v3 Announce Type: replace-cross Abstract: In the hypothesis selection problem, we are given sample and query access to finite set of candidate distributions (hypotheses), $\mathcal{H} = \{H_1, \ldots, H_n\}$, and samples from an unknown distribution $P$, both over a domain $\mathcal{X}$.

By Anders Aamand, Maryam Aliakbarpour, Justin Y. Chen, Sandeep Silwal
arXiv Machine Learning
Aug 3

Parameter-Free Heavy-Tailed Bandits

arXiv:2607. 29460v1 Announce Type: new Abstract: Heavy-tailed distributions arise naturally in sequential decision-making problems such as financial investment, online advertising, and network management, where rare but extreme outcomes can dominate performance.

By Gianmarco Genalti, Alberto Maria Metelli
arXiv Machine Learning
Aug 4

Meritocratic Fairness via $K$-Shapley Values in Budgeted Combinatorial Bandits with Full-Bandit Feedback

arXiv:2605. 00762v2 Announce Type: replace Abstract: We study meritocratic fairness in budgeted combinatorial multi-armed bandits with full-bandit feedback, where a learner selects at most $K$ arms per time step and observes only the noisy aggregate reward of the selected set.

By Shradha Sharma, Shweta Jain, Swapnil Dhamal
arXiv Machine Learning
Oct 12

A Critical Look at Power Sampling when Test Time Sharpening LLMs

arXiv:2610. 13653v1 Announce Type: cross Abstract: Reinforcement learning with verifiable rewards (RLVR) has substantially improved LLM reasoning, yet growing evidence suggests it mainly performs distribution sharpening: concentrating probability mass on reasoning paths the base model already produces.

By Abiel Malkani Talwar, Christopher Nemeth, Henry Moss