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arxiv: 2605.24937 · v1 · pith:Q46DFTVHnew · submitted 2026-05-24 · 🧮 math.PR · cs.NA· math.NA· math.OC· stat.CO· stat.ML

Error estimates for tamed Euler and Randomized Euler schemes for SDEs with locally Lipschitz drift with applications to non-logconcave sampling and optimization

Pith reviewed 2026-06-29 23:52 UTC · model grok-4.3

classification 🧮 math.PR cs.NAmath.NAmath.OCstat.COstat.ML
keywords tamed Euler schemeslocally Lipschitz driftSDE discretizationnon-logconcave samplinglogarithmic Sobolev inequalityLangevin Monte Carloerror estimatesnon-convex optimization
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The pith

Tamed Euler schemes deliver near-optimal sampling complexities for distributions with superlinear drift under logarithmic Sobolev inequalities.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper develops local error frameworks for tamed and randomized Euler discretizations of SDEs whose drift is locally Lipschitz with superlinear growth. These frameworks produce non-asymptotic bounds on the discretization error in KL divergence for the KL-accelerated tamed unadjusted Langevin algorithm and in total variation for the new tamed randomized midpoint scheme. Under the assumption that the invariant measure satisfies a logarithmic Sobolev inequality, the bounds translate into iteration complexities of order tilde O of epsilon to the minus one half for the first scheme and tilde O of epsilon to the minus one for the second. The same results also supply non-asymptotic guarantees for non-convex optimization problems. Readers care because these rates are near-optimal and the schemes remain stable where classical Euler-Maruyama fails.

Core claim

The paper claims that two new local-error frameworks, built on the shifted-composition method, give finite-time non-asymptotic error estimates for kTULA in KL divergence and for tRLMC in total variation that hold for arbitrary locally Lipschitz drifts; specializing to targets obeying a logarithmic Sobolev inequality produces the near-optimal iteration complexities in sampling and corresponding bounds for optimization.

What carries the argument

The shifted-composition approach applied to tamed schemes, which controls the local truncation error despite the absence of global Lipschitz continuity.

If this is right

  • kTULA achieves tilde O of epsilon to the minus one half complexity in KL, TV, and Wasserstein metrics for sampling.
  • tRLMC achieves tilde O of epsilon to the minus one complexity in total variation and Wasserstein for the first time under super-linear growth.
  • Non-asymptotic excess risk bounds follow for non-convex optimization via both schemes.
  • The frameworks apply to general SDE approximation beyond the sampling setting.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Similar taming techniques could be combined with other acceleration methods to improve the complexity further.
  • The results suggest that randomized midpoint schemes may be preferable when total variation guarantees are required.
  • Explicit dependence on the log-Sobolev constant could guide parameter tuning in applications.

Load-bearing premise

The target distribution obeys a logarithmic Sobolev inequality, allowing conversion of local discretization errors into global iteration counts.

What would settle it

Running the schemes on a low-dimensional test SDE with known log-Sobolev constant and superlinear drift, then checking whether the measured error after the predicted number of steps stays below the stated bound.

read the original abstract

In this paper, we study the numerical discretization of stochastic differential equations with locally Lipschitz, super-linearly growing drift, and the resulting implications for sampling from non-log-concave distributions satisfying a logarithmic Sobolev inequality. In this regime, the classical Euler--Maruyama scheme underlying the unadjusted Langevin algorithm (ULA) is known to be unstable. We analyze the KL-accelerated tamed unadjusted Langevin algorithm (kTULA) and introduce a new tamed randomized midpoint scheme, termed tRLMC. Building on the shifted-composition approach of \cite{chewi2024local}, we develop two new local-error frameworks that yield finite-time, non-asymptotic error estimates against the underlying SDE -- in KL divergence for kTULA, and in total variation for tRLMC -- valid for general locally Lipschitz drift. Specializing these frameworks to the sampling problem under a logarithmic Sobolev inequality, we obtain a near-optimal $\widetilde{O}(\varepsilon^{-1/2})$ iteration complexity for kTULA in KL divergence, with corresponding guarantees in total variation and Wasserstein distance. We further establish, for the first time, a non-asymptotic guarantee in total variation for a tamed randomized Langevin scheme under super-linear drift growth, together with the corresponding Wasserstein-distance bound, both with $\widetilde{O}(\varepsilon^{-1})$ complexity for tRLMC. As a consequence, both schemes yield non-asymptotic bounds for a non-convex excess-risk optimization problem.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 3 minor

Summary. The manuscript develops two local-error frameworks for discretizations of SDEs with locally Lipschitz super-linear drift, using a shifted-composition argument. For the KL-accelerated tamed ULA (kTULA) it obtains non-asymptotic KL error bounds against the continuous process; for the new tamed randomized midpoint scheme (tRLMC) it obtains total-variation bounds. Specializing under a logarithmic Sobolev inequality on the target yields iteration complexities ilde O(ε^{-1/2}) for kTULA in KL (with TV and W_2 corollaries) and ilde O(ε^{-1}) for tRLMC in TV (with W_2 corollary). The same bounds are applied to a non-convex excess-risk optimization problem.

Significance. If the local-error frameworks are valid, the work supplies the first non-asymptotic TV guarantee for a tamed randomized Langevin scheme under super-linear growth and near-optimal sampling rates for kTULA. The explicit dependence on the LSI constant and the extension of shifted composition to these schemes are concrete contributions to the analysis of non-log-concave sampling.

minor comments (3)
  1. §3.2, Definition 3.3: the precise statement of the 'shifted composition' operator should be restated verbatim from Chewi et al. (2024) so that the subsequent error propagation lemmas are self-contained.
  2. Theorem 4.5 (tRLMC TV bound): the dependence on the step-size restriction h ≤ c / (L^2 + M^2) is stated only in the proof; moving the explicit constant into the theorem statement would improve readability.
  3. Table 1: the row for 'tRLMC (this work)' lists TV complexity ilde O(ε^{-1}); it would be helpful to add a footnote clarifying that this is the first such guarantee under super-linear growth.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive assessment, the recognition of the local-error frameworks and complexity results, and the recommendation of minor revision. No specific major comments were raised in the report.

Circularity Check

0 steps flagged

No significant circularity; new frameworks independent of inputs

full rationale

The paper cites an external reference (chewi2024local) for the shifted-composition approach and then develops two new local-error frameworks for KL and TV that apply to general locally Lipschitz super-linear drift. These frameworks are specialized under an explicit LSI assumption to obtain the iteration complexities. No derivation step reduces by construction to a fitted parameter, self-definition, or self-citation chain; the central non-asymptotic guarantees are presented as novel analysis rather than re-labeling of inputs. The LSI is stated as an additional ingredient required only for the sampling rates, not smuggled via citation. This is a standard self-contained derivation with external support.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claims rest on the logarithmic Sobolev inequality for the target measure and the local Lipschitz plus superlinear growth condition on the drift; both are standard domain assumptions rather than new postulates.

axioms (2)
  • domain assumption The target probability measure satisfies a logarithmic Sobolev inequality.
    Invoked to specialize the general KL and TV error bounds to concrete iteration complexities for sampling.
  • domain assumption The drift coefficient is locally Lipschitz and exhibits super-linear growth.
    Defines the regime in which classical Euler-Maruyama is unstable and the tamed schemes are analyzed.

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discussion (0)

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Works this paper leans on

36 extracted references · 11 canonical work pages · 1 internal anchor

  1. [1]

    Diffusions hypercontractives

    Dominique Bakry and Michel ´Emery. Diffusions hypercontractives. InS ´eminaire de Probabilit´es XIX 1983/84: Proceedings, pages 177–206. Springer, 2006

  2. [2]

    Geometric ergodicity of modified euler schemes for sdes with super-linearity.arXiv preprint arXiv:2412.19377, 2024

    Jianhai Bao, Mateusz B Majka, and Jian Wang. Geometric ergodicity of modified euler schemes for sdes with super-linearity.arXiv preprint arXiv:2412.19377, 2024

  3. [3]

    The tamed unadjusted Langevin algorithm.Stochastic Processes and their Applications, 129(10):3638–3663, 2019

    Nicolas Brosse, Alain Durmus, ´Eric Moulines, and Sotirios Sabanis. The tamed unadjusted Langevin algorithm.Stochastic Processes and their Applications, 129(10):3638–3663, 2019

  4. [4]

    Complexity of randomized algorithms for underdamped langevin dynamics.arXiv preprint arXiv:2003.09906, 2020

    Yu Cao, Jianfeng Lu, and Lihan Wang. Complexity of randomized algorithms for underdamped langevin dynamics.arXiv preprint arXiv:2003.09906, 2020

  5. [5]

    Shifted composition: A local error framework for kl analysis of sampling algorithms.Journal of Machine Learning Research, 25(123):1–42, 2024

    Sinho Chewi, Jason Altschuler, and Holden Lu. Shifted composition: A local error framework for kl analysis of sampling algorithms.Journal of Machine Learning Research, 25(123):1–42, 2024

  6. [6]

    Erdogdu, Mufan Bill Li, Ruoqi Shen, and Matthew Zhang

    Sinho Chewi, Murat A. Erdogdu, Mufan Bill Li, Ruoqi Shen, and Matthew Zhang. Analysis of langevin monte carlo from poincar´e to log-sobolev, 2024

  7. [7]

    Dalalyan

    Arnak S. Dalalyan. Theoretical guarantees for approximate sampling from smooth and log-concave densities, 2016. 37

  8. [8]

    Arnak S Dalalyan. Theoretical guarantees for approximate sampling from smooth and log-concave densities.Journal of the Royal Statistical Society: Series B (Statistical Methodology), 79(3): 651–676, 2017

  9. [9]

    Nonasymptotic convergence analysis for the unadjusted Langevin algorithm.The Annals of Applied Probability, 27(3):1551–1587, 2017

    Alain Durmus, Eric Moulines, et al. Nonasymptotic convergence analysis for the unadjusted Langevin algorithm.The Annals of Applied Probability, 27(3):1551–1587, 2017

  10. [10]

    High-dimensional Bayesian inference via the unadjusted Langevin algorithm.Bernoulli, 25(4A):2854–2882, 2019

    Alain Durmus, Eric Moulines, et al. High-dimensional Bayesian inference via the unadjusted Langevin algorithm.Bernoulli, 25(4A):2854–2882, 2019

  11. [11]

    On the convergence of langevin monte carlo: The interplay between tail growth and smoothness

    Murat A Erdogdu and Rasa Hosseinzadeh. On the convergence of langevin monte carlo: The interplay between tail growth and smoothness. InConference on Learning Theory, pages 1776–

  12. [12]

    Erdogdu, Rasa Hosseinzadeh, and Shunshi Zhang

    Murat A. Erdogdu, Rasa Hosseinzadeh, and Shunshi Zhang. Convergence of langevin monte carlo in chi-squared and r ´enyi divergence. InInternational Conference on Artificial Intelligence and Statistics, pages 8151–8175. PMLR, 2022

  13. [13]

    Martin Hutzenthaler, Arnulf Jentzen, and Peter E. Kloeden. Strong convergence of an explicit numerical method for sdes with nonglobally lipschitz continuous coefficients.Ann. Appl. Probab., 22(4):1611–1641, 08 2012

  14. [14]

    Laplace’s method revisited: Weak convergence of probability measures.The Annals of Probability, 8(6):1177–1182, 1980

    Chii-Ruey Hwang. Laplace’s method revisited: Weak convergence of probability measures.The Annals of Probability, 8(6):1177–1182, 1980

  15. [15]

    Johnston, I

    T. Johnston, I. Lytras, and S. Sabanis. Kinetic langevin mcmc sampling without gradient lipschitz continuity—the strongly convex case.J. Complex., 85, 2024

  16. [16]

    Convergence rate of randomized midpoint langevin monte carlo.arXiv preprint arXiv:2511.13093, 2025

    Ruinan Li, Tian Shen, and Zhonggen Su. Convergence rate of randomized midpoint langevin monte carlo.arXiv preprint arXiv:2511.13093, 2025

  17. [17]

    Dong-Young Lim, Ariel Neufeld, Sotirios Sabanis, and Ying Zhang. Non-asymptotic estimates for TUSLA algorithm for non-convex learning with applications to neural networks with ReLU activation function.IMA Journal of Numerical Analysis, page drad038, 2023

  18. [18]

    Non-asymptotic estimates for tusla algorithm for non-convex learning with applications to neural networks with relu activation function, 2023

    Dong-Young Lim, Ariel Neufeld, Sotirios Sabanis, and Ying Zhang. Non-asymptotic estimates for tusla algorithm for non-convex learning with applications to neural networks with relu activation function, 2023. URLhttps://arxiv.org/abs/2107.08649

  19. [19]

    Taming neural networks with tusla: Nonconvex learning via adaptive stochastic gradient langevin algorithms.SIAM Journal on Mathematics of Data Science, 5(2):323–345, 2023

    Attila Lovas, Iosif Lytras, Mikl ´os R´asonyi, and Sotirios Sabanis. Taming neural networks with tusla: Nonconvex learning via adaptive stochastic gradient langevin algorithms.SIAM Journal on Mathematics of Data Science, 5(2):323–345, 2023

  20. [20]

    Lytras and S

    I. Lytras and S. Sabanis. Taming under isoperimetry.Stochastic Process. Appl., 188, 2025

  21. [21]

    Contractive kinetic langevin samplers beyond global lipschitz continuity.arXiv preprint arXiv: 2509.12031, 2025

    Iosif Lytras and Panagiotis Mertikopoulos. Contractive kinetic langevin samplers beyond global lipschitz continuity.arXiv preprint arXiv: 2509.12031, 2025

  22. [22]

    Lytras and P

    Iosif Lytras and Panayotis Mertikopoulos. Tamed langevin sampling under weaker conditions.arXiv preprint arXiv:2405.17693, 2024

  23. [23]

    ktula: A langevin sampling algorithm with improved kl bounds under super-linear log-gradients.arXiv preprint arXiv:2506.04878, 2025

    Iosif Lytras, Sotirios Sabanis, and Ying Zhang. ktula: A langevin sampling algorithm with improved kl bounds under super-linear log-gradients.arXiv preprint arXiv:2506.04878, 2025

  24. [24]

    Non-asymptotic bounds for sampling algorithms without log-concavity.arXiv preprint arXiv:1808.07105, 2018

    Mateusz B Majka, Aleksandar Mijatovi´c, and Lukasz Szpruch. Non-asymptotic bounds for sampling algorithms without log-concavity.arXiv preprint arXiv:1808.07105, 2018

  25. [25]

    Towards a complete analysis of langevin monte carlo: Beyond poincar´e inequality

    Alireza Mousavi-Hosseini, Tyler K Farghly, Ye He, Krishna Balasubramanian, and Murat A Erdogdu. Towards a complete analysis of langevin monte carlo: Beyond poincar´e inequality. InThe Thirty Sixth Annual Conference on Learning Theory, pages 1–35. PMLR, 2023

  26. [26]

    Non-asymptotic convergence bounds for modified tamed unadjusted langevin algorithm in non-convex setting, 2024

    Ariel Neufeld, Matthew Ng Cheng En, and Ying Zhang. Non-asymptotic convergence bounds for modified tamed unadjusted langevin algorithm in non-convex setting, 2024. URL https: //arxiv.org/abs/2207.02600

  27. [27]

    Non-convex learning via stochastic gradient langevin dynamics: a nonasymptotic analysis

    Maxim Raginsky, Alexander Rakhlin, and Matus Telgarsky. Non-convex learning via stochastic gradient langevin dynamics: a nonasymptotic analysis. InConference on Learning Theory, pages 1674–1703, 2017

  28. [28]

    A note on tamed euler approximations.Electron

    Sotirios Sabanis. A note on tamed euler approximations.Electron. Commun. Probab., 18(47):1–10, 2013

  29. [29]

    Euler approximations with varying coefficients: the case of superlinearly growing diffusion coefficients.The Annals of Applied Probability, 26(4):2083–2105, 2016

    Sotirios Sabanis. Euler approximations with varying coefficients: the case of superlinearly growing diffusion coefficients.The Annals of Applied Probability, 26(4):2083–2105, 2016

  30. [30]

    The randomized midpoint method for log-concave sampling.Advances in Neural Information Processing Systems, 32, 2019

    Ruoqi Shen and Yin Tat Lee. The randomized midpoint method for log-concave sampling.Advances in Neural Information Processing Systems, 32, 2019. 38 I. LYTRAS AND A. NTOUSIS

  31. [31]

    Rapid convergence of the unadjusted langevin algorithm: Isoperimetry suffices.Advances in neural information processing systems, 32, 2019

    Santosh Vempala and Andre Wibisono. Rapid convergence of the unadjusted langevin algorithm: Isoperimetry suffices.Advances in neural information processing systems, 32, 2019

  32. [32]

    Harnack inequality for sde with multiplicative noise and extension to neumann semigroup on nonconvex manifolds.The Annals of Probability, 39(4), 2011

    Feng-Yu Wang. Harnack inequality for sde with multiplicative noise and extension to neumann semigroup on nonconvex manifolds.The Annals of Probability, 39(4), 2011

  33. [33]

    When Langevin Monte Carlo Meets Randomization: New Sampling Algorithms with Non-asymptotic Error Bounds beyond Log-Concavity and Gradient Lipschitzness

    Xiaojie Wang and Bin Yang. When langevin monte carlo meets randomization: Non-asymptotic error bounds beyond log-concavity and gradient lipschitzness.arXiv preprint arXiv:2509.25630, 2025

  34. [34]

    Non-asymptotic error bounds in w2-distance with sqrt(d) dimen- sion dependence and first order convergence for langevin monte carlo beyond log-concavity

    Bin Yang and Xiaojie Wang. Non-asymptotic error bounds in w2-distance with sqrt(d) dimen- sion dependence and first order convergence for langevin monte carlo beyond log-concavity. In Proceedings of the 42nd International Conference on Machine Learning, pages 71358–71382, 2025

  35. [35]

    Error analysis of time-discrete random batch method for interacting particle systems and associated mean-field limits.IMA Journal of Numerical Analysis, 44(3): 1660–1698, 2024

    Xuda Ye and Zhennan Zhou. Error analysis of time-discrete random batch method for interacting particle systems and associated mean-field limits.IMA Journal of Numerical Analysis, 44(3): 1660–1698, 2024

  36. [36]

    Langevin monte carlo for strongly log-concave distributions: Randomized midpoint revisited.arXiv preprint arXiv:2306.08494, 2023

    Lu Yu, Avetik Karagulyan, and Arnak Dalalyan. Langevin monte carlo for strongly log-concave distributions: Randomized midpoint revisited.arXiv preprint arXiv:2306.08494, 2023. ARCHIMEDES, ATHENARESEARCHCENTER, GREECE ANDNATIONALTECHNICALUNIVERSITY OFATHENS, ATHENS,GREECE. Email address:i.lytras@athenarc.gr ∗ ARCHIMEDES, ATHENARESEARCHCENTER, GREECE Email ...