arXiv:2510.16208cs.LGcs.SY2025-10被引 1

针对动态环境下的动作-收益关系,提出分阶段优化算法,实现近最优后悔值。

Explore-then-Commit for Nonstationary Linear Bandits with Latent Dynamics

  • 先探索后决策:用随机动作估计系统动态参数
  • 在有限时长内达到约T^{2/3}的后悔上界
  • 适合需长期策略优化的非平稳强化学习场景

我们研究一种非平稳多臂老虎机问题,其中收益同时依赖于动作和隐状态,而隐状态由未知的线性动态系统驱动。关键的是,状态动态也受动作影响,导致短期与长期收益之间存在张力。我们为有限时长$T$设计了一种探索-然后-承诺算法。在探索阶段,采用随机Rademacher动作以估计线性动态系统的马尔可夫参数,这些参数刻画了动作与收益的关系。在承诺阶段,算法利用估计参数设计出最大化长期收益的动作序列。所提算法实现了$ ilde{oldsymbol{ ext{O}}}(T^{2/3})$的后悔上界。分析解决了两个核心挑战:从时间相关的收益中学习,以及设计具有最优长期收益的动作序列。我们通过提供基于双线性收益的系统辨识的近最优样本复杂度和误差界来应对第一个挑战;通过证明其等价于超立方体上的不定二次优化(已知为NP难问题),并给出该问题的次优性保证,从而实现后悔上界。最后,我们提出了基于半定松弛与Goemans-Williamson舍入的实用方法。

原文摘要 · Abstract (English)

We study a nonstationary bandit problem where rewards depend on both actions and latent states, the latter governed by unknown linear dynamics. Crucially, the state dynamics also depend on the actions, resulting in tension between short-term and long-term rewards. We propose an explore-then-commit algorithm for a finite horizon $T$. During the exploration phase, random Rademacher actions enable estimation of the Markov parameters of the linear dynamics, which characterize the action-reward relationship. In the commit phase, the algorithm uses the estimated parameters to design an optimized action sequence for long-term reward. Our proposed algorithm achieves $\tilde{\mathcal{O}}(T^{2/3})$ regret. Our analysis handles two key challenges: learning from temporally correlated rewards, and designing action sequences with optimal long-term reward. We address the first challenge by providing near-optimal sample complexity and error bounds for system identification using bilinear rewards. We address the second challenge by proving an equivalence with indefinite quadratic optimization over a hypercube, a known NP-hard problem. We provide a sub-optimality guarantee for this problem, enabling our regret upper bound. Lastly, we propose a semidefinite relaxation with Goemans-Williamson rounding as a practical approach.

强化学习非平稳在线优化动态系统

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