arXiv:2503.15294cs.LG2025-03被引 7

揭示高维大间隔半空间的可复制性极限,解决多个开放问题。

Borsuk-Ulam and Replicable Learning of Large-Margin Halfspaces

  • 基于局部Borsuk-Ulam定理证明下界,拓扑方法突破传统分析。
  • 在d维空间中,最大可复制列表长度为d,与维度线性相关。
  • 适用于学习理论、通信复杂性研究者,尤其关注随机与伪确定性差异。

我们证明了d维γ-边缘半空间的列表可复制性数满足 $ \frac{d}{2}+1 \le \mathrm{LR}(H^d_γ) \le d $,且随维度增长。该结果解决了多个开放问题: • 任意将无限维大边缘半空间消歧为全概念类时,其Littlestone维数无界,回应Alon等(FOCS '21)之问; • 大间隙情形下Gap Hamming距离问题的公共随机通信复杂度无界,回答Fang等(STOC '25)之问; • 随机与伪确定性通信复杂度存在O(1)与ω(1)的分离; • 任意有限点集与齐次半空间在d维欧氏空间中的最大列表可复制性为d,解决Chase、Moran、Yehudayoff(FOCS '23)之题; • 存在Littlestone维数为1的偏概念类,其所有消歧均具无穷Littlestone维数,回应Cheung等(ICALP '23)之问。下界由局部Borsuk-Ulam定理导出,上界通过SVM泛化性质构造可复制学习规则。

原文摘要 · Abstract (English)

We prove that the list replicability number of $d$-dimensional $γ$-margin half-spaces satisfies \[ \frac{d}{2}+1 \le \mathrm{LR}(H^d_γ) \le d, \] which grows with dimension. This resolves several open problems: $\bullet$ Every disambiguation of infinite-dimensional large-margin half-spaces to a total concept class has unbounded Littlestone dimension, answering an open question of Alon, Hanneke, Holzman, and Moran (FOCS '21). $\bullet$ Every disambiguation of the Gap Hamming Distance problem in the large gap regime has unbounded public-coin randomized communication complexity. This answers an open question of Fang, Göös, Harms, and Hatami (STOC '25). $\bullet$ There is a separation of $O(1)$ vs $ω(1)$ between randomized and pseudo-deterministic communication complexity. $\bullet$ The maximum list-replicability number of any finite set of points and homogeneous half-spaces in $d$-dimensional Euclidean space is $d$, resolving a problem of Chase, Moran, and Yehudayoff (FOCS '23). $\bullet$ There exists a partial concept class with Littlestone dimension $1$ such that all its disambiguations have infinite Littlestone dimension. This resolves a problem of Cheung, H. Hatami, P. Hatami, and Hosseini (ICALP '23). Our lower bound follows from a topological argument based on a local Borsuk-Ulam theorem. For the upper bound, we construct a list-replicable learning rule using the generalization properties of SVMs.

学习理论拓扑学习通信复杂性

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