On the Convergence Rate of Sinkhorn's Algorithm

Fuente: arXiv
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Hauptverfasser: Ghosal, Promit, Nutz, Marcel
Format: Preprint
Veröffentlicht: 2022
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author Ghosal, Promit
Nutz, Marcel
author_facet Ghosal, Promit
Nutz, Marcel
contents We study Sinkhorn's algorithm for solving the entropically regularized optimal transport problem. Its iterate $π_{t}$ is shown to satisfy $H(π_{t}|π_{*})+H(π_{*}|π_{t})=O(t^{-1})$ where $H$ denotes relative entropy and $π_{*}$ the optimal coupling. This holds for a large class of cost functions and marginals, including quadratic cost with subgaussian marginals. We also obtain the rate $O(t^{-1})$ for the dual suboptimality and $O(t^{-2})$ for the marginal entropies. More precisely, we derive non-asymptotic bounds, and in contrast to previous results on linear convergence that are limited to bounded costs, our estimates do not deteriorate exponentially with the regularization parameter. We also obtain a stability result for $π_{*}$ as a function of the marginals, quantified in relative entropy.
format Preprint
id arxiv_https___arxiv_org_abs_2212_06000
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle On the Convergence Rate of Sinkhorn's Algorithm
Ghosal, Promit
Nutz, Marcel
Optimization and Control
Analysis of PDEs
Probability
90C25, 49N05
We study Sinkhorn's algorithm for solving the entropically regularized optimal transport problem. Its iterate $π_{t}$ is shown to satisfy $H(π_{t}|π_{*})+H(π_{*}|π_{t})=O(t^{-1})$ where $H$ denotes relative entropy and $π_{*}$ the optimal coupling. This holds for a large class of cost functions and marginals, including quadratic cost with subgaussian marginals. We also obtain the rate $O(t^{-1})$ for the dual suboptimality and $O(t^{-2})$ for the marginal entropies. More precisely, we derive non-asymptotic bounds, and in contrast to previous results on linear convergence that are limited to bounded costs, our estimates do not deteriorate exponentially with the regularization parameter. We also obtain a stability result for $π_{*}$ as a function of the marginals, quantified in relative entropy.
title On the Convergence Rate of Sinkhorn's Algorithm
topic Optimization and Control
Analysis of PDEs
Probability
90C25, 49N05
url https://arxiv.org/abs/2212.06000