Le Cam's method, Fano's inequality, and Assouad's lemma are three widely used
techniques to prove lower bounds for statistical estimation tasks. We propose
their analogues under central differential privacy. Our results are simple,
easy to apply and we use them to establish sample complexity bounds in several
estimation tasks. We establish the optimal sample complexity of discrete
distribution estimation under total variation distance and $\ell_2$ distance.
We also provide lower bounds for several other distribution classes, including
product distributions and Gaussian mixtures that are tight up to logarithmic
factors. The technical component of our paper relates coupling between
distributions to the sample complexity of estimation under differential
privacy.

本文使用中心差分隐私提出了 Le Cam 方法、Fano 不等式和 Assouad 引理的类似物，并且通过该方法在多个统计估计任务中建立了样本复杂性边界，包括离散分布估计和 l2 距离评估。我们还提供了针对几个其他分布类别的下界，包括产品分布和高斯混合分布，这些下界在对数因子上是精确的。我们的技术贡献在于将分布之间的耦合与基于差分隐私的估计的样本复杂度相关联。