解决自适应数据下SGD的收敛性问题,适用于动态环境中的在线优化。
Stochastic Gradient Descent with Adaptive Data
- 提出自适应数据流收敛的简单判定条件
- 证明收敛速度与独立同分布情形相近,仅需考虑策略动态混合时间
- 适用于库存、排队等运筹学场景,可分析强化学习样本复杂度
随机梯度下降(SGD)是一种强大的优化方法,尤其适用于在线学习。其在独立同分布(iid)数据假设下的收敛性已有较充分研究。然而,在运筹学中的策略优化问题中,策略会改变环境,从而影响后续数据,导致数据流非平稳、非独立且受历史决策影响。这种依赖关系引入梯度估计偏差,可能引发传统iid设定下不存在的在线学习不稳定性。本文提出简单条件,确保自适应数据流下SGD的收敛性。我们证明,只要考虑策略诱导动态的混合时间,其收敛速度与经典iid情形基本相当。通过李雅普诺夫函数分析,可将运筹学中已有的随机系统稳定性结果转化为SGD的收敛速率,并应用于排队和库存管理问题。此外,展示了该结果如何用于分析演员-评论家策略梯度算法的样本复杂度。
原文摘要 · Abstract (English)
Stochastic gradient descent (SGD) is a powerful optimization technique that is particularly useful in online learning scenarios. Its convergence analysis is relatively well understood under the assumption that the data samples are independent and identically distributed (iid). However, applying SGD to policy optimization problems in operations research involves a distinct challenge: the policy changes the environment and thereby affects the data used to update the policy. The adaptively generated data stream involves samples that are non-stationary, no longer independent from each other, and affected by previous decisions. The influence of previous decisions on the data generated introduces bias in the gradient estimate, which presents a potential source of instability for online learning not present in the iid case. In this paper, we introduce simple criteria for the adaptively generated data stream to guarantee the convergence of SGD. We show that the convergence speed of SGD with adaptive data is largely similar to the classical iid setting, as long as the mixing time of the policy-induced dynamics is factored in. Our Lyapunov-function analysis allows one to translate existing stability analysis of stochastic systems studied in operations research into convergence rates for SGD, and we demonstrate this for queueing and inventory management problems. We also showcase how our result can be applied to study the sample complexity of an actor-critic policy gradient algorithm.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。