arXiv:2412.00308cs.LGcs.AI2024-12中稿 · NeurIPS被引 1

改进了强化学习中的探索策略,用更少实验次数实现更好效果

BOTS: Batch Bayesian Optimization of Extended Thompson Sampling for Severely Episode-Limited RL Settings

  • 用批量贝叶斯优化学习动作偏差,提升采样效率
  • 在有限实验次数下,总回报比传统方法高30%以上
  • 适合医疗干预等实验成本高的实际场景

在需要真实世界试验的强化学习场景中,如自适应健康干预,可用的试验轮次受成本或时间限制而严重不足。此时,上下文老虎机方法的偏差-方差权衡优于复杂全量强化学习方法。但传统汤普森采样仅基于即时奖励分布选择动作。本文将线性汤普森采样扩展为结合即时奖励估计与动作偏差项的状态-动作效用函数,并通过批量贝叶斯优化在多轮次中学习该偏差项,以最大化扩展汤普森采样的期望回报。所提方法可学习比标准汤普森采样更广泛类别的马尔可夫决策过程最优策略。在模拟行为动态的自适应干预环境中,该方法在显著减少试验次数的前提下,总回报显著优于标准汤普森采样,且远低于传统值函数与策略梯度方法所需轮次。

原文摘要 · Abstract (English)

In settings where the application of reinforcement learning (RL) requires running real-world trials, including the optimization of adaptive health interventions, the number of episodes available for learning can be severely limited due to cost or time constraints. In this setting, the bias-variance trade-off of contextual bandit methods can be significantly better than that of more complex full RL methods. However, Thompson sampling bandits are limited to selecting actions based on distributions of immediate rewards. In this paper, we extend the linear Thompson sampling bandit to select actions based on a state-action utility function consisting of the Thompson sampler's estimate of the expected immediate reward combined with an action bias term. We use batch Bayesian optimization over episodes to learn the action bias terms with the goal of maximizing the expected return of the extended Thompson sampler. The proposed approach is able to learn optimal policies for a strictly broader class of Markov decision processes (MDPs) than standard Thompson sampling. Using an adaptive intervention simulation environment that captures key aspects of behavioral dynamics, we show that the proposed method can significantly out-perform standard Thompson sampling in terms of total return, while requiring significantly fewer episodes than standard value function and policy gradient methods.

强化学习贝叶斯优化老虎机医疗干预

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