arXiv:2504.10139stat.MLcs.LG2025-04NeurIPS被引 1

提出新方法直接压缩带标签数据的条件分布,效果优于传统联合分布压缩。

Conditional Distribution Compression via the Kernel Conditional Mean Embedding

  • 基于核条件均值嵌入,提出线性时间的条件分布压缩算法ACKH
  • ACKIP在条件分布保留上显著优于联合分布压缩和贪心算法
  • 适合需要精准条件建模的任务,如个性化推荐与因果推断

现有分布压缩方法(如核采样,KH)最初针对无标签数据设计。然而,尚无方法能直接压缩带标签数据的条件分布。为此,本文首先引入平均最大条件均值差异(AMCMD)作为比较条件分布的度量,并推导出闭式估计器。关键发现:在分布压缩场景下,基于AMCMD构建压缩集的计算复杂度可从立方级降至线性级。据此,我们扩展KH,提出平均条件核采样(ACKH),一种线性时间的贪心算法,用于构造目标为AMCMD的压缩集。为进一步对比,引入联合核采样(JKH),即适应于压缩标签数据联合分布的KH变体。尽管采样方法具有简单可解释的优点,但依赖贪心策略。为此,我们还提出联合核诱导点(JKIP)与平均条件核诱导点(ACKIP),在保持线性复杂度的同时联合优化压缩集。实验表明,直接保留条件分布的ACKIP优于联合分布压缩及ACKH的贪心选择;同时,JKIP始终优于JKH。

原文摘要 · Abstract (English)

Existing distribution compression methods, like Kernel Herding (KH), were originally developed for unlabelled data. However, no existing approach directly compresses the conditional distribution of \textit{labelled} data. To address this gap, we first introduce the Average Maximum Conditional Mean Discrepancy (AMCMD), a metric for comparing conditional distributions, and derive a closed form estimator. Next, we make a key observation: in the context of distribution compression, the cost of constructing a compressed set targeting the AMCMD can be reduced from cubic to linear. Leveraging this, we extend KH to propose Average Conditional Kernel Herding (ACKH), a linear-time greedy algorithm for constructing compressed sets that target the AMCMD. To better understand the advantages of directly compressing the conditional distribution rather than doing so via the joint distribution, we introduce Joint Kernel Herding (JKH), an adaptation of KH designed to compress the joint distribution of labelled data. While herding methods provide a simple and interpretable selection process, they rely on a greedy heuristic. To explore alternative optimisation strategies, we also propose Joint Kernel Inducing Points (JKIP) and Average Conditional Kernel Inducing Points (ACKIP), which jointly optimise the compressed set while maintaining linear complexity. Experiments show that directly preserving conditional distributions with ACKIP outperforms both joint distribution compression and the greedy selection used in ACKH. Moreover, we see that JKIP consistently outperforms JKH.

分布压缩条件分布核方法线性算法

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