论文标题

超越最坏的对手的甲骨文有效的在线学习

Oracle-Efficient Online Learning for Beyond Worst-Case Adversaries

论文作者

Haghtalab, Nika, Han, Yanjun, Shetty, Abhishek, Yang, Kunhe

论文摘要

在本文中,我们研究了甲骨文效率的算法,以超越对在线学习的最坏情况分析。我们专注于两个设置。首先,[rst11,hrs22]的平滑分析设置,其中对手受到限制,从而从密度上限的分布中生成样品,其上限为$ 1/σ$乘以均匀密度的乘以。其次,设置$ k $ hint trandductive学习,在该学习中,学习者可以访问每个时间步骤的$ k $提示,保证包含真实实例。我们为这两种设置提供了第一个已知的Oracle效率算法,仅取决于类和参数的伪(或VC)尺寸$σ$和$ k $,从而捕获了对手的力量。特别是,我们实现了$ \ widetilde {o}(\ sqrt {tdσ^{ - 1}})$和$ \ widetilde {o}(\ sqrt {t dk})$的$ \ widetilde {o}(\ sqrt { dσ^{ - \ frac {1} {2}}}})$用于学习二进制值函数。对于平滑的分析设置,我们的结果为使用平滑的对手提供了第一种用于在线学习的Oracle效率算法[HRS22]。这与[HK16]建立的最差的对手和离线学习之间的在线学习之间的计算分离对比。我们的算法还可以在带有小域的最坏情况下达到改善的界限。特别是,我们给出了$ o(\ sqrt {t(d | \ Mathcal {x} |)^{1/2}})$的遗憾的甲骨文算法,这是对早期$ o(\ sqrt {\ sqrt {

In this paper, we study oracle-efficient algorithms for beyond worst-case analysis of online learning. We focus on two settings. First, the smoothed analysis setting of [RST11,HRS22] where an adversary is constrained to generating samples from distributions whose density is upper bounded by $1/σ$ times the uniform density. Second, the setting of $K$-hint transductive learning, where the learner is given access to $K$ hints per time step that are guaranteed to include the true instance. We give the first known oracle-efficient algorithms for both settings that depend only on the pseudo (or VC) dimension of the class and parameters $σ$ and $K$ that capture the power of the adversary. In particular, we achieve oracle-efficient regret bounds of $ \widetilde{O} ( \sqrt{T dσ^{-1}} ) $ and $ \widetilde{O} ( \sqrt{T dK} ) $ for learning real-valued functions and $ O ( \sqrt{T dσ^{-\frac{1}{2}} } )$ for learning binary-valued functions. For the smoothed analysis setting, our results give the first oracle-efficient algorithm for online learning with smoothed adversaries [HRS22]. This contrasts the computational separation between online learning with worst-case adversaries and offline learning established by [HK16]. Our algorithms also achieve improved bounds for worst-case setting with small domains. In particular, we give an oracle-efficient algorithm with regret of $O ( \sqrt{T(d |\mathcal{X}|)^{1/2} })$, which is a refinement of the earlier $O ( \sqrt{T|\mathcal{X}|})$ bound by [DS16].

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