Accelerated Sinkhorn Algorithms for Partial Optimal Transport
Nghia Thu Truong, Qui Phu Pham, Quang Nguyen, Dung Luong, Mai Tran
TL;DR
Partial Optimal Transport (POT) enables robust mass transport under unequal marginals by capping transported mass. The paper introduces ASPOT, an accelerated Sinkhorn-based POT method that achieves a near-linear dependence on the problem size via Nesterov-style momentum and Greenkhorn updates, yielding a complexity of $\mathcal{O}(n^{7/3}\varepsilon^{-5/3})$, and it analyzes a Tuned Sinkhorn variant that further improves rates through a data-driven choice of $\gamma$. Theoretical results provide dual-progress bounds, iteration complexity, and approximation guarantees, while experiments on color transfer and point-cloud registration demonstrate faster convergence and higher-quality transport maps than existing baselines. Together, these findings offer practical guidelines for parameter tuning and show the potential of momentum-based acceleration to scale POT to larger and multi-marginal problems.
Abstract
Partial Optimal Transport (POT) addresses the problem of transporting only a fraction of the total mass between two distributions, making it suitable when marginals have unequal size or contain outliers. While Sinkhorn-based methods are widely used, their complexity bounds for POT remain suboptimal and can limit scalability. We introduce Accelerated Sinkhorn for POT (ASPOT), which integrates alternating minimization with Nesterov-style acceleration in the POT setting, yielding a complexity of $\mathcal{O}(n^{7/3}\varepsilon^{-5/3})$. We also show that an informed choice of the entropic parameter $γ$ improves rates for the classical Sinkhorn method. Experiments on real-world applications validate our theories and demonstrate the favorable performance of our proposed methods.
