Exactly or Approximately Wasserstein Distributionally Robust Estimation According to Wasserstein Radii Being Small or Large

Fuente: arXiv
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Main Authors: Ding, Xiao, Song, Enbin, Niu, Dunbiao, Cao, Zhujun, Shi, Qingjiang
Format: Preprint
Published: 2025
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author Ding, Xiao
Song, Enbin
Niu, Dunbiao
Cao, Zhujun
Shi, Qingjiang
author_facet Ding, Xiao
Song, Enbin
Niu, Dunbiao
Cao, Zhujun
Shi, Qingjiang
contents This paper primarily considers the robust estimation problem under Wasserstein distance constraints on the parameter and noise distributions in the linear measurement model with additive noise, which can be formulated as an infinite-dimensional nonconvex minimax problem. We prove that the existence of a saddle point for this problem is equivalent to that for a finite-dimensional minimax problem, and give a counterexample demonstrating that the saddle point may not exist. Motivated by this observation, we present a verifiable necessary and sufficient condition whose parameters can be derived from a convex problem and its dual. Additionally, we also introduce a simplified sufficient condition, which intuitively indicates that when the Wasserstein radii are small enough, the saddle point always exists. In the absence of the saddle point, we solve an finite-dimensional nonconvex minimax problem, obtained by restricting the estimator to be linear. Its optimal value establishes an upper bound on the robust estimation problem, while its optimal solution yields a robust linear estimator. Numerical experiments are also provided to validate our theoretical results.
format Preprint
id arxiv_https___arxiv_org_abs_2510_01763
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exactly or Approximately Wasserstein Distributionally Robust Estimation According to Wasserstein Radii Being Small or Large
Ding, Xiao
Song, Enbin
Niu, Dunbiao
Cao, Zhujun
Shi, Qingjiang
Signal Processing
Optimization and Control
Statistics Theory
This paper primarily considers the robust estimation problem under Wasserstein distance constraints on the parameter and noise distributions in the linear measurement model with additive noise, which can be formulated as an infinite-dimensional nonconvex minimax problem. We prove that the existence of a saddle point for this problem is equivalent to that for a finite-dimensional minimax problem, and give a counterexample demonstrating that the saddle point may not exist. Motivated by this observation, we present a verifiable necessary and sufficient condition whose parameters can be derived from a convex problem and its dual. Additionally, we also introduce a simplified sufficient condition, which intuitively indicates that when the Wasserstein radii are small enough, the saddle point always exists. In the absence of the saddle point, we solve an finite-dimensional nonconvex minimax problem, obtained by restricting the estimator to be linear. Its optimal value establishes an upper bound on the robust estimation problem, while its optimal solution yields a robust linear estimator. Numerical experiments are also provided to validate our theoretical results.
title Exactly or Approximately Wasserstein Distributionally Robust Estimation According to Wasserstein Radii Being Small or Large
topic Signal Processing
Optimization and Control
Statistics Theory
url https://arxiv.org/abs/2510.01763