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Towards instance-dependent regret optimality in Episodic MDPs with Posterior Sampling

We study regret minimization in finite-horizon episodic Markov Decision Processes (MDPs). While minimax-optimal algorithms are known, tractable approaches to instance-dependent optimality are still lacking. Motivated by this gap, we introduce …

A Perturbation Approach to Unconstrained Linear Bandits

We revisit the standard perturbation-based approach of Abernethy et al. (2008) in the context of unconstrained Bandit Linear Optimization (uBLO). We show the surprising result that in the unconstrained setting, this approach effectively reduces …

Does Stochastic Gradient really succeed for bandits?

Recent works of Mei et al. (2023, 2024) have deepened the theoretical understanding of the Stochastic Gradient Bandit (SGB) policy, showing that using a constant learning rate guarantees asymptotic convergence to the optimal policy, and that …

Non-stationary Bandit Convex Optimization: A Comprehensive Study

Bandit Convex Optimization is a fundamental class of sequential decision-making problems, where the learner selects actions from a continuous domain and observes a loss (but not its gradient) at only one point per round. We study this problem in …

Improved learning rates in multi-unit uniform price auctions

Motivated by the strategic participation of electricity producers in electricity day-ahead market, we study the problem of online learning in repeated multi-unit uniform price auctions. The main contribution of this paper is the introduction of a new …

The Value of Reward Lookahead in Reinforcement Learning

In reinforcement learning (RL), agents sequentially interact with changing environments while aiming to maximize the obtained rewards. Usually, rewards are observed only after acting, and so the goal is to maximize the expected cumulative reward. …

Lookback Prophet Inequalities

Prophet inequalities are fundamental optimal stopping problems, where a decision-maker observes sequentially items with values sampled independently from known distributions, and must decide at each new observation to either stop and gain the current …

Optimizing the coalition gain in Online Auctions with Greedy Structured Bandits

Motivated by online display advertising, this work considers repeated second-price auctions, where agents sample their value from an unknown distribution with cumulative distribution function F. In each auction t, a decision-maker bound by limited …

Multi-Armed Bandits with Guaranteed Revenue per Arm

We consider a Multi-Armed Bandit problem with covering constraints, where the primary goal is to ensure that each arm receives a minimum expected reward while maximizing the total cumulative reward. In this scenario, the optimal policy then belongs …

Fast asymptotically optimal algorithms for non-parametric stochastic bandits

We consider the problem of regret minimization in non-parametric stochastic bandits. When the rewards are known to be bounded from above, there exists asymptotically optimal algorithms, with asymptotic regret depending on an infimum of …