提出一种高精度流形采样方法,理论保证收敛快,适合复杂几何结构数据采样。
Riemannian Proximal Sampler for High-accuracy Sampling on Manifolds
- 基于黎曼近似点法构建采样器,依赖布朗增量与热核两个核心算子。
- 理论上在KL散度下仅需O(log(1/ε))次迭代即可达到ε精度,变体在总变差下为O(log²(1/ε))。
- 通过热核截断和渐近公式实现可计算的算子,适用于流形上概率分布采样任务。
我们提出黎曼近似点采样器(Riemannian Proximal Sampler),用于从定义在黎曼流形上的概率密度采样。该采样器性能依赖于两个关键算子:流形布朗增量(MBI)和黎曼热核(RHK)。我们建立了高精度采样保证:在使用精确算子时,达到ε-精度的样本只需O(log(1/ε))次迭代(以KL散度衡量);使用足够精确的近似算子时,在总变差距离下需要O(log²(1/ε))次迭代。我们通过热核截断和Varadhan渐近公式实现了这两个算子的实用化。在此基础上,将采样器解释为熵正则化黎曼近似点法在相应Wasserstein空间中的离散化。初步数值实验验证了该方法的有效性。
原文摘要 · Abstract (English)
We introduce the Riemannian Proximal Sampler, a method for sampling from densities defined on Riemannian manifolds. The performance of this sampler critically depends on two key oracles: the Manifold Brownian Increments (MBI) oracle and the Riemannian Heat-kernel (RHK) oracle. We establish high-accuracy sampling guarantees for the Riemannian Proximal Sampler, showing that generating samples with $\varepsilon$-accuracy requires $O(\log(1/\varepsilon))$ iterations in Kullback-Leibler divergence assuming access to exact oracles and $O(\log^2(1/\varepsilon))$ iterations in the total variation metric assuming access to sufficiently accurate inexact oracles. Furthermore, we present practical implementations of these oracles by leveraging heat-kernel truncation and Varadhan's asymptotics. In the latter case, we interpret the Riemannian Proximal Sampler as a discretization of the entropy-regularized Riemannian Proximal Point Method on the associated Wasserstein space. We provide preliminary numerical results that illustrate the effectiveness of the proposed methodology.
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