arXiv AI

When More Objectives Make Identification Easier: The Role of Preferences and Feedback

The paper investigates best‑arm identification (BAI) in multi‑objective bandits, showing that additional objectives can actually reduce the number of samples needed. For Gaussian bandits, a characteristic‑time lower bound is derived that applies uniformly across preference orders, and explicit comparisons under Pareto, linear, and lexicographic preferences reveal that a larger optimal set can be identified with fewer samples, that the benefit of vector feedback depends on the preference, and that multi‑objective BAI can outperform the easiest single‑objective case. The authors also introduce Order‑Aware Track‑and‑Stop (OATS), an algorithm that achieves the lower bound while guaranteeing correctness at any desired confidence level.

arXiv AI
Oct 1

On the Complexity of Preference-Based Bandits

The paper investigates preference-based bandits where a learner selects pairs of arms and receives binary preference feedback modeled by Bradley–Terry. It introduces the locally sensitive eluder dimension, a new complexity measure for logistic preference feedback, and proposes the GINOP algorithm that uses log-loss confidence sets to balance optimism and exploration. The authors prove a first-order regret bound showing that learning with preference feedback can be as statistically efficient as learning from direct rewards, and they validate their theory with empirical experiments.

By Ahmed Ben Yahmed (CREST, ENSAE Paris, FAIRPLAY), Marc Abeille (FAIRPLAY), Cl\'ement Calauz\`enes (FAIRPLAY)
Hugging Face Trending Papers
Jul 16

MESHA: Mechanism-Enforced Sequential Halving for Strategic Linear Bandits

We design and analyze \underline{M}echanism-\underline{E}nforced \underline{S}equential \underline{HA}lving (MESHA), an algorithm for Best Arm Identification (BAI) in strategic linear bandits. In this setting, each arm may strategically misreport its feature vector to maximize the probability of being identified as the best arm, when rewards are generated from the arms' true but unobservable features.