Quantitative contraction rates for Sinkhorn's algorithm: beyond bounded costs and compact marginals
Pith reviewed 2026-05-24 08:59 UTC · model grok-4.3
The pith
Sinkhorn's algorithm converges exponentially to Schrödinger potentials for entropic optimal transport on R^d under a log-concavity profile condition on the marginals.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We show non-asymptotic exponential convergence of Sinkhorn iterates to the Schrödinger potentials, solutions of the quadratic Entropic Optimal Transport problem on R^d, under the assumption that the marginal inputs admit an asymptotically positive log-concavity profile. These are the first such results without assuming bounded cost functions or compactly supported marginals.
What carries the argument
The asymptotically positive log-concavity profile of the marginal inputs, which is used to derive contraction estimates for the Sinkhorn map.
Load-bearing premise
The marginal inputs must admit an asymptotically positive log-concavity profile.
What would settle it
A pair of marginal distributions without an asymptotically positive log-concavity profile for which the Sinkhorn iterates fail to converge at an exponential rate.
read the original abstract
We show non-asymptotic exponential convergence of Sinkhorn iterates to the Schr\"odinger potentials, solutions of the quadratic Entropic Optimal Transport problem on $\mathbb{R}^ d$. Our results hold under mild assumptions on the marginal inputs: in particular, we only assume that they admit an asymptotically positive log-concavity profile, covering as special cases log-concave distributions and bounded smooth perturbations of quadratic potentials. Up to the authors' knowledge, these are the first results which establish exponential convergence of Sinkhorn's algorithm in a general setting without assuming bounded cost functions or compactly supported marginals.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper claims to establish non-asymptotic exponential convergence of the Sinkhorn iterates to the Schrödinger potentials solving the quadratic entropic optimal transport problem on R^d. The results rely on the assumption that the input marginals admit an asymptotically positive log-concavity profile; this condition is shown to cover log-concave distributions as well as bounded smooth perturbations of quadratic potentials, thereby dispensing with the classical requirements of bounded cost functions and compactly supported marginals.
Significance. If the derivation holds, the work supplies the first quantitative, non-asymptotic convergence guarantees for Sinkhorn’s algorithm on unbounded domains in Euclidean space. The asymptotically positive log-concavity profile is a mild, explicitly verifiable condition that meaningfully enlarges the set of admissible marginals; the explicit (non-vacuous) constants and the removal of compactness hypotheses constitute a clear technical advance for the analysis of entropic optimal transport.
minor comments (3)
- [Abstract] The abstract states that the constants are explicit, yet the dependence on dimension d and on the parameters of the log-concavity profile is not displayed; a short display of the leading constants in the main theorem would improve readability.
- Notation for the log-concavity profile (Definition 2.3 or equivalent) should be introduced before its first use in the statement of the main convergence theorem.
- Figure captions and axis labels in any numerical illustrations should explicitly indicate the marginals and the value of the profile parameter used.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of the manuscript, accurate summary of the contributions, and recommendation of minor revision. The report raises no specific major comments.
Circularity Check
No significant circularity; derivation is self-contained analytic argument
full rationale
The paper claims non-asymptotic exponential convergence of Sinkhorn iterates to Schrödinger potentials under the explicit assumption that marginals admit an asymptotically positive log-concavity profile. This assumption is positioned as the minimal condition removing bounded-cost and compact-support hypotheses, and the result is derived directly from it via analytic estimates. No quoted step reduces a prediction to a fitted parameter by construction, invokes a self-citation as the sole justification for a uniqueness theorem, or renames an empirical pattern. The provided abstract and claim structure contain no load-bearing self-referential definitions or ansatzes smuggled via prior work. This is the normal case of an independent derivation.
Axiom & Free-Parameter Ledger
Forward citations
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Reference graph
Works this paper leans on
-
[1]
Learning to solve inverse problems using Wasserstein loss
Jonas Adler, Axel Ringh, Ozan ¨Oktem, and Johan Karlsson. Learning to solve inverse problems using Wasserstein loss. arXiv preprint arXiv:1710.10898 , 2017
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[2]
Wassers tein generative adversarial networks
Martin Arjovsky, Soumith Chintala, and L´ eon Bottou. Wassers tein generative adversarial networks. In International conference on machine learning , pages 214–223. PMLR, 2017
work page 2017
-
[3]
Julio Backhoff, Giovanni Conforti, Ivan Gentil, and Christian L´ eo nard. The mean field Schr¨ odinger problem: ergodic behavior, entropy estimates and func- tional inequalities. Probability Theory and Related Fields , 178(1):475–530, 2020
work page 2020
-
[4]
Analysis and geometry of Markov diffusion operators , volume 348
Dominique Bakry, Ivan Gentil, and Michel Ledoux. Analysis and geometry of Markov diffusion operators , volume 348. Springer Science & Business Media, 2013
work page 2013
-
[5]
Optimal transportation, modelling and num erical sim- ulation
Jean-David Benamou. Optimal transportation, modelling and num erical sim- ulation. Acta Numerica, 30:249–325, 2021
work page 2021
-
[6]
Iterative Bregman projections for regularized t ransportation problems
Jean-David Benamou, Guillaume Carlier, Marco Cuturi, Luca Nenna , and Gabriel Peyr´ e. Iterative Bregman projections for regularized t ransportation problems. SIAM Journal on Scientific Computing , 37(2):A1111–A1138, 2015
work page 2015
-
[7]
An entropy minimization approach to second-order variational mea n-field games
Jean-David Benamou, Guillaume Carlier, Simone Di Marino, and Luca Nenna. An entropy minimization approach to second-order variational mea n-field games. Mathematical Models and Methods in Applied Sciences , 29(08):1553– 1583, 2019
work page 2019
-
[8]
The Sinkhorn algorithm, parabolic optimal tran sport and geometric Monge–Amp` ere equations
Robert J Berman. The Sinkhorn algorithm, parabolic optimal tran sport and geometric Monge–Amp` ere equations. Numerische Mathematik , 145(4):771– 836, 2020
work page 2020
-
[9]
Entropy minimization, DAD problems, and doubly stochastic kernels
Jonathan M Borwein, Adrian Stephen Lewis, and Roger Nussbaum . Entropy minimization, DAD problems, and doubly stochastic kernels. Journal of Func- tional Analysis , 123(2):264–307, 1994
work page 1994
-
[10]
On the Linear Convergence of the Multimarginal Sinkhorn Algorithm
Guillaume Carlier. On the Linear Convergence of the Multimarginal Sinkhorn Algorithm. SIAM Journal on Optimization , 32(2):786–794, 2022
work page 2022
-
[11]
A Differential Approach to t he Multi-Marginal Schr¨ odinger System
Guillaume Carlier and Maxime Laborde. A Differential Approach to t he Multi-Marginal Schr¨ odinger System. SIAM Journal on Mathematical Anal- ysis, 52(1):709–717, 2020
work page 2020
-
[12]
Entropic a nd Displace- ment Interpolation: A Computational Approach Using the Hilbert Me tric
Yongxin Chen, Tryphon Georgiou, and Michele Pavon. Entropic a nd Displace- ment Interpolation: A Computational Approach Using the Hilbert Me tric. SIAM Journal on Applied Mathematics , 76(6):2375–2396, 2016. EXPONENTIAL CONVERGENCE OF SINKHORN’S ALGORITHM 31
work page 2016
-
[13]
Yongxin Chen, Tryphon Georgiou, and Michele Pavon. On the rela tion between optimal transport and Schr¨ odinger bridges: A stochastic contr ol viewpoint. Journal of Optimization Theory and Applications , 169(2):671–691, 2016
work page 2016
-
[14]
Stochast ic control liaisons: Richard Sinkhorn meets Gaspard Monge on a Schr¨ odinger b ridge
Yongxin Chen, Tryphon Georgiou, and Michele Pavon. Stochast ic control liaisons: Richard Sinkhorn meets Gaspard Monge on a Schr¨ odinger b ridge. SIAM Review , 63(2):249–313, 2021
work page 2021
-
[15]
An entropic genera lization of Caffarelli’s contraction theorem via covariance inequalities
Sinho Chewi and Aram-Alexandre Pooladian. An entropic genera lization of Caffarelli’s contraction theorem via covariance inequalities. Comptes Rendus. Math´ ematique, 361:1471–1482, 2023
work page 2023
-
[16]
Alberto Chiarini, Giovanni Conforti, Giacomo Greco, and Luca Ta manini. Gra- dient estimates for the Schr¨ odinger potentials: convergence tothe Brenier map and quantitative stability. Communications in Partial Differential Equations , 48(6):895–943, 2023
work page 2023
-
[17]
Giovanni Conforti. A second order equation for Schr¨ odinger bridges with appli- cations to the hot gas experiment and entropic transportation co st. Probability Theory and Related Fields , 174(1):1–47, 2019
work page 2019
-
[18]
Giovanni Conforti. Weak semiconvexity estimates for Schr¨ od inger potentials and logarithmic Sobolev inequality for Schr¨ odinger bridges. accepted in Prob- ability Theory and Related Fields , 2024
work page 2024
-
[19]
Around the entropic Talagr and inequal- ity
Giovanni Conforti and Luigia Ripani. Around the entropic Talagr and inequal- ity. Bernoulli, 26(2):1431–1452, 2020
work page 2020
-
[20]
Sinkhorn distances: Lightspeed computation of optimal trans- port
Marco Cuturi. Sinkhorn distances: Lightspeed computation of optimal trans- port. In Advances in Neural Information Processing Systems , pages 2292–2300, 2013
work page 2013
-
[21]
Dif- fusion Schr¨ odinger bridge with applications to score-based gener ative model- ing
Valentin De Bortoli, James Thornton, Jeremy Heng, and Arnaud Doucet. Dif- fusion Schr¨ odinger bridge with applications to score-based gener ative model- ing. Advances in Neural Information Processing Systems , 34, 2021
work page 2021
-
[22]
Qua ntitative uniform stability of the iterative proportional fitting procedure
George Deligiannidis, Valentin de Bortoli, and Arnaud Doucet. Qua ntitative uniform stability of the iterative proportional fitting procedure. The Annals of Applied Probability , 34(1A):501 – 516, 2024
work page 2024
-
[23]
Simone Di Marino and Augusto Gerolin. An Optimal Transport App roach for the Schr¨ odinger Bridge Problem and Convergence of Sinkhorn Algorithm. Journal of Scientific Computing , 85(2):27, 2020
work page 2020
-
[24]
Texture mapping via optima l mass transport
Ayelet Dominitz and Allen Tannenbaum. Texture mapping via optima l mass transport. IEEE transactions on visualization and computer graphics , 16(3):419–433, 2009
work page 2009
-
[25]
Reflection couplings and contraction rates fo r diffusions
Andreas Eberle. Reflection couplings and contraction rates fo r diffusions. Prob- ability Theory and Related Fields , 166(3-4):851–886, 2016
work page 2016
-
[26]
Stephan Eckstein. Hilbert’s projective metric for functions of bounded growth and exponential convergence of Sinkhorn’s algorithm. arXiv preprint arXiv:2311.04041, 2023
-
[27]
Quantitative Stability of Re gularized Op- timal Transport and Convergence of Sinkhorn’s Algorithm
Stephan Eckstein and Marcel Nutz. Quantitative Stability of Re gularized Op- timal Transport and Convergence of Sinkhorn’s Algorithm. SIAM Journal on Mathematical Analysis, 54(6):5922–5948, 2022
work page 2022
-
[28]
A proof of t he Caffarelli contraction theorem via entropic regularization
Max Fathi, Nathael Gozlan, and Maxime Prodhomme. A proof of t he Caffarelli contraction theorem via entropic regularization. Calculus of Variations and Partial Differential Equations , 59(96), 2020. 32 GIOV ANNI CONFORTI, ALAIN OLIVIERO DURMUS, AND GIACOMO GR ECO
work page 2020
-
[29]
On the scaling of multidimensional matrices
Joel Franklin and Jens Lorenz. On the scaling of multidimensional matrices. Linear Algebra and its Applications , 114-115:717–735, 1989
work page 1989
-
[30]
Ivan Gentil, Christian L´ eonard, and Luigia Ripani. Dynamical asp ects of the generalized Schr¨ odinger problem via Otto calculus–A heuristic point of view. Revista Matem´ atica Iberoamericana, 36(4):1071–1112, 2020
work page 2020
-
[31]
An en- tropic interpolation proof of the HWI inequality
Ivan Gentil, Christian L´ eonard, Luigia Ripani, and Luca Tamanini. An en- tropic interpolation proof of the HWI inequality. Stochastic Processes and their Applications, 130(2):907–923, 2020
work page 2020
-
[32]
On the Convergence Rate of S inkhorn’s Algorithm
Promit Ghosal and Marcel Nutz. On the Convergence Rate of S inkhorn’s Algorithm. arXiv preprint arXiv:2212.06000 , 2022
-
[33]
Benamou-Brenier and duality formu las for the entropic cost on RCD ∗ (K,N ) spaces
Nicola Gigli and Luca Tamanini. Benamou-Brenier and duality formu las for the entropic cost on RCD ∗ (K,N ) spaces. Probability Theory and Related Fields , pages 1–34, 2019
work page 2019
-
[34]
Second order differentiation formu la on RCD ∗ (K,N ) spaces
Nicola Gigli and Luca Tamanini. Second order differentiation formu la on RCD ∗ (K,N ) spaces. Journal of the European Mathematical Society , 23(5):1727–1795, 2021
work page 2021
-
[35]
The Schr¨ odinger problem: where analysis meets stochastic s
Giacomo Greco. The Schr¨ odinger problem: where analysis meets stochastic s. Phd Thesis (Graduation TU/e), Mathematics and Computer Science , May
-
[36]
Non- asymptotic convergence bounds for Sinkhorn iterates and their g radients: a coupling approach
Giacomo Greco, Maxence Noble, Giovanni Conforti, and Alain Dur mus. Non- asymptotic convergence bounds for Sinkhorn iterates and their g radients: a coupling approach. In Gergely Neu and Lorenzo Rosasco, editors, Proceedings of Thirty Sixth Conference on Learning Theory , volume 195 of Proceedings of Machine Learning Research, pages 716–746. PMLR, 12–15 Jul 2023
work page 2023
-
[37]
Foundations of Modern Probability, volume 293 of Probability Theory and Stochastic Modelling
Olav Kallenberg. Foundations of Modern Probability, volume 293 of Probability Theory and Stochastic Modelling . Springer Cham, 3 edition, 2021
work page 2021
-
[38]
Optimal mass transport: Signal processing and machine-le arning ap- plications
Soheil Kolouri, Se Rim Park, Matthew Thorpe, Dejan Slepcev, an d Gustavo K Rohde. Optimal mass transport: Signal processing and machine-le arning ap- plications. IEEE signal processing magazine , 34(4):43–59, 2017
work page 2017
-
[39]
From word embeddings to document distances
Matt Kusner, Yu Sun, Nicholas Kolkin, and Kilian Weinberger. From word embeddings to document distances. In Francis Bach and David Blei, e ditors, Proceedings of the 32nd International Conference on Machin e Learning , vol- ume 37 of Proceedings of Machine Learning Research , pages 957–966, Lille, France, 07–09 Jul 2015. PMLR
work page 2015
-
[40]
A gradient descent perspective on Sinkhorn
Flavien L´ eger. A gradient descent perspective on Sinkhorn. Applied Mathe- matics & Optimization , 84(2):1843–1855, 2021
work page 2021
-
[41]
A survey of the Schr¨ odinger problem and some of its con- nections with optimal transport
Christian L´ eonard. A survey of the Schr¨ odinger problem and some of its con- nections with optimal transport. Discrete and Continuous Dynamical Systems , 34(4):1533–1574, 2014
work page 2014
-
[42]
Jonathan C. Mattingly, Andrew M. Stuart, and Desmond J. High am. Ergodic- ity for SDEs and approximations: locally Lipschitz vector fields and de generate noise. Stochastic Processes and their Applications , 102(2):185–232, 2002
work page 2002
-
[43]
Sean P. Meyn and R. L. Tweedie. Stability of Markovian Processe s III: Foster- Lyapunov Criteria for Continuous-Time Processes. Advances in Applied Prob- ability, 25(3):518–548, 1993
work page 1993
-
[44]
Duality theorem for the stoc hastic opti- mal control problem
Toshio Mikami and Mich` ele Thieullen. Duality theorem for the stoc hastic opti- mal control problem. Stochastic processes and their applications, 116(12):1815– 1835, 2006. EXPONENTIAL CONVERGENCE OF SINKHORN’S ALGORITHM 33
work page 2006
-
[45]
The dynami- cal Schr¨ odinger problem in abstract metric spaces
L´ eonard Monsaingeon, Luca Tamanini, and Dmitry Vorotnikov. The dynami- cal Schr¨ odinger problem in abstract metric spaces. Advances in Mathematics , 426:109100, 2023
work page 2023
-
[46]
Introduction to Entropic Optimal Transport
Marcel Nutz. Introduction to Entropic Optimal Transport. http: // www. math. columbia. edu/~ mnutz/ docs/ EOT_ lecture_ notes. pdf, 2021
work page 2021
-
[47]
Entropic optimal transport : convergence of potentials
Marcel Nutz and Johannes Wiesel. Entropic optimal transport : convergence of potentials. Probability Theory and Related Fields , 184(1):401–424, 2022
work page 2022
-
[48]
Stability of Schr¨ odinger pot entials and convergence of Sinkhorn’s algorithm
Marcel Nutz and Johannes Wiesel. Stability of Schr¨ odinger pot entials and convergence of Sinkhorn’s algorithm. The Annals of Probability , 51(2):699 – 722, 2023
work page 2023
-
[49]
Multiplicative Schr¨ odinger problem and the Dirichlet transport
Soumik Pal and Ting-Kam Leonard Wong. Multiplicative Schr¨ odinger problem and the Dirichlet transport. Probability Theory and Related Fields , 178(1- 2):613–654, 2020
work page 2020
-
[50]
Entropic Approximation of Wasserstein Gradient Flows
Gabriel Peyr´ e. Entropic Approximation of Wasserstein Gradient Flows. SIAM Journal on Imaging Sciences , 8(4):2323–2351, 2015
work page 2015
-
[51]
Computational Optimal Tran sport
Gabriel Peyr´ e and Marco Cuturi. Computational Optimal Tran sport. Foun- dations and Trends in Machine Learning , 11(5-6):355–607, 2019
work page 2019
-
[52]
Entropic e stimation of optimal transport maps
Aram-Alexandre Pooladian and Jonathan Niles-Weed. Entropic e stimation of optimal transport maps. arXiv preprint arXiv:2109.12004 , 2021
-
[53]
Daniel Revuz and Marc Yor. Continuous Martingales and Brownian Motion , volume 293 of Grundlehren der mathematischen Wissenschaften . Springer Berlin, Heidelberg, 3 edition, 1999
work page 1999
-
[54]
Gareth O. Roberts and Richard L. Tweedie. Exponential conve rgence of Langevin distributions and their discrete approximations. Bernoulli, 2(4):341– 363, 1996
work page 1996
-
[55]
Convergence of the iterative proport ional fitting proce- dure
Ludger Ruschendorf. Convergence of the iterative proport ional fitting proce- dure. The Annals of Statistics , pages 1160–1174, 1995
work page 1995
-
[56]
La th´ eorie relativiste de l’´ electron et l’ interpr´ etation de la m´ ecanique quantique.Ann
Erwin Schr¨ odinger. La th´ eorie relativiste de l’´ electron et l’ interpr´ etation de la m´ ecanique quantique.Ann. Inst Henri Poincar´ e, (2):269 – 310, 1932
work page 1932
-
[57]
A Relationship Between Arbitrary Positive Mat rices and Doubly Stochastic Matrices
Richard Sinkhorn. A Relationship Between Arbitrary Positive Mat rices and Doubly Stochastic Matrices. The Annals of Mathematical Statistics , 35(2):876– 879, 1964
work page 1964
-
[58]
Concerning nonnegative mat rices and doubly stochastic matrices
Richard Sinkhorn and Paul Knopp. Concerning nonnegative mat rices and doubly stochastic matrices. Pacific Journal of Mathematics , 21(2):343–348, 1967
work page 1967
-
[59]
Convolution al wasser- stein distances: Efficient optimal transportation on geometric dom ains
Justin Solomon, Fernando De Goes, Gabriel Peyr´ e, Marco Cut uri, Adrian Butscher, Andy Nguyen, Tao Du, and Leonidas Guibas. Convolution al wasser- stein distances: Efficient optimal transportation on geometric dom ains. ACM Transactions on Graphics (ToG) , 34(4):1–11, 2015. 34 GIOV ANNI CONFORTI, ALAIN OLIVIERO DURMUS, AND GIACOMO GR ECO ´Ecole Polytechniq...
work page 2015
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