论文标题
投影稳健的Wasserstein距离和Riemannian优化
Projection Robust Wasserstein Distance and Riemannian Optimization
论文作者
论文摘要
投影强大的Wasserstein(PRW)距离或Wasserstein投影追踪(WPP)是Wasserstein距离的强大变体。最近的工作表明,该数量比标准的Wasserstein距离更强大,特别是在比较高维度的概率度量时。但是,它被排除在实际应用中,因为优化模型本质上是非凸面和非平滑型,这使计算棘手。我们在本文中的贡献是要重新审视WPP/PRW背后的原始动机,但是要以艰难的途径表明,尽管具有毫无疑问和非平滑度,尽管〜\ citet {Niles-2019-2019-启示证明了一些硬度的结果,但在prw/wpp的原始效果中,可以使用prw/wpp \ textian的效率{优化,在相关情况下的行为比其凸松弛更好。更具体地说,我们在其复杂性结合(在附录中的一个)上提供了三种简单的算法,并提供了可靠的理论保证,并通过对合成和真实数据进行广泛的实验来证明它们的有效性和效率。本文提供了PRW距离的计算理论的第一步,并提供了最佳运输与Riemannian优化之间的联系。
Projection robust Wasserstein (PRW) distance, or Wasserstein projection pursuit (WPP), is a robust variant of the Wasserstein distance. Recent work suggests that this quantity is more robust than the standard Wasserstein distance, in particular when comparing probability measures in high-dimensions. However, it is ruled out for practical application because the optimization model is essentially non-convex and non-smooth which makes the computation intractable. Our contribution in this paper is to revisit the original motivation behind WPP/PRW, but take the hard route of showing that, despite its non-convexity and lack of nonsmoothness, and even despite some hardness results proved by~\citet{Niles-2019-Estimation} in a minimax sense, the original formulation for PRW/WPP \textit{can} be efficiently computed in practice using Riemannian optimization, yielding in relevant cases better behavior than its convex relaxation. More specifically, we provide three simple algorithms with solid theoretical guarantee on their complexity bound (one in the appendix), and demonstrate their effectiveness and efficiency by conducing extensive experiments on synthetic and real data. This paper provides a first step into a computational theory of the PRW distance and provides the links between optimal transport and Riemannian optimization.