pith. sign in

arxiv: 2605.19467 · v1 · pith:2KS5VGEXnew · submitted 2026-05-19 · 🧮 math.OC

Convergence of iterates and improved rates for accelerated augmented Lagrangian methods for linearly constrained convex optimization

Pith reviewed 2026-05-20 04:46 UTC · model grok-4.3

classification 🧮 math.OC
keywords augmented Lagrangian methodNesterov extrapolationconvergence rateslinear constraintsconvex optimizationprimal-dual algorithmfeasibility violationobjective residual
0
0 comments X

The pith

Accelerated augmented Lagrangian methods converge to saddle points with o(1/k^2) rates for feasibility violation and objective residual when parameters avoid the critical regime.

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

The paper introduces a family of accelerated augmented Lagrangian methods that incorporate Nesterov extrapolation parameters for linearly constrained convex optimization problems with differentiable objectives. It proves that the primal-dual sequence generated by these schemes converges to a saddle point while delivering accelerated rates on the augmented Lagrangian gap, the feasibility violation, and the objective residual. In the noncritical parameter regime the rates strengthen from the conventional O(1/k^2) to the stricter little-o(1/k^2) decay. The authors note that little-o rates simultaneously covering both feasibility and objective residual have not appeared before for accelerated augmented Lagrangian methods in this setting.

Core claim

Under suitable parameter conditions the implicit-gradient and partially explicit variants ensure convergence of the primal-dual sequence to a saddle point, while the augmented Lagrangian gap, feasibility violation, and objective residual each satisfy accelerated estimates that improve to little-o(1/k^2) once the Nesterov extrapolation parameters lie outside the critical regime.

What carries the argument

Nesterov extrapolation parameters embedded in the augmented Lagrangian iteration that can be chosen in the noncritical regime to secure both iterate convergence and the little-o rate improvement.

If this is right

  • The primal-dual sequence converges to a saddle point of the constrained problem.
  • The augmented Lagrangian gap, feasibility violation, and objective residual each enjoy accelerated convergence estimates.
  • In the noncritical regime these three quantities improve from O(1/k^2) to little-o(1/k^2).
  • The results hold for both continuously differentiable convex objectives (implicit-gradient variant) and smooth convex objectives (partially explicit variant).

Where Pith is reading between the lines

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

  • The same noncritical tuning strategy may transfer to other inertial primal-dual schemes that rely on extrapolation parameters.
  • Explicit characterization of the noncritical interval could simplify parameter selection in software implementations.
  • Stochastic or distributed versions of the method might inherit the little-o feasibility and residual rates under analogous parameter restrictions.

Load-bearing premise

Suitable non-critical choices of the Nesterov extrapolation parameters exist that simultaneously guarantee convergence and produce the improved little-o rates.

What would settle it

A concrete linearly constrained convex problem together with a sequence of noncritical parameters for which the feasibility violation or objective residual fails to decay faster than C/k^2 for any fixed C.

read the original abstract

We consider a linearly constrained convex optimization problem with a differentiable objective function. Motivated by an inertial primal-dual dynamical system with vanishing damping, we propose a class of accelerated augmented Lagrangian methods with Nesterov extrapolation parameters. The framework contains two variants: an implicit-gradient scheme for convex continuously differentiable objectives and a partially explicit scheme for convex smooth objectives. Under suitable parameter conditions, we prove convergence of the primal-dual sequence to a saddle point, together with accelerated estimates for the augmented Lagrangian gap, the feasibility violation, and the objective residual. In the noncritical parameter regime, these estimates are improved from $O(1/k^2)$ to $o(1/k^2)$. To the best of our knowledge, such little-o rates for both feasibility violation and objective residual have not been previously established for accelerated augmented Lagrangian methods in this setting.

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

1 major / 1 minor

Summary. The manuscript proposes a class of accelerated augmented Lagrangian methods with Nesterov extrapolation parameters for linearly constrained convex optimization problems with differentiable objectives. Motivated by an inertial primal-dual dynamical system with vanishing damping, the framework includes an implicit-gradient scheme for convex C1 objectives and a partially explicit scheme for smooth convex objectives. Under suitable parameter conditions, the authors prove convergence of the primal-dual sequence to a saddle point along with accelerated estimates for the augmented Lagrangian gap, feasibility violation, and objective residual; in the noncritical parameter regime these estimates improve from O(1/k²) to o(1/k²).

Significance. If the central claims hold, the work would be a solid contribution to the analysis of accelerated first-order methods for constrained convex problems. The explicit link to a continuous inertial dynamical system supplies useful intuition, and the reported little-o rates for feasibility violation and objective residual would be novel in this setting. The distinction between critical and noncritical regimes for the extrapolation parameters adds technical nuance that could inform future parameter tuning.

major comments (1)
  1. [Abstract and §4] Abstract and statements of the main convergence theorems (e.g., Theorems 3.1–3.3 and the rate results in §4): the improved o(1/k²) claims for the augmented Lagrangian gap, feasibility violation, and objective residual rest on the existence of Nesterov extrapolation parameters that simultaneously place the scheme in the noncritical regime and guarantee primal-dual convergence. The manuscript invokes this only through the phrases “under suitable parameter conditions” and “in the noncritical parameter regime” without supplying an explicit, problem-independent construction or a general existence argument that works for arbitrary convex differentiable objectives. This is load-bearing for the central rate-improvement claim.
minor comments (1)
  1. [§2] The notation for the augmented Lagrangian gap and the precise definition of the critical versus noncritical regimes should be introduced with a short self-contained paragraph in §2 before the algorithm statements, to improve readability for readers outside the immediate subfield.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful reading and the positive evaluation of our manuscript. We address the major comment below.

read point-by-point responses
  1. Referee: [Abstract and §4] Abstract and statements of the main convergence theorems (e.g., Theorems 3.1–3.3 and the rate results in §4): the improved o(1/k²) claims for the augmented Lagrangian gap, feasibility violation, and objective residual rest on the existence of Nesterov extrapolation parameters that simultaneously place the scheme in the noncritical regime and guarantee primal-dual convergence. The manuscript invokes this only through the phrases “under suitable parameter conditions” and “in the noncritical parameter regime” without supplying an explicit, problem-independent construction or a general existence argument that works for arbitrary convex differentiable objectives. This is load-bearing for the central rate-improvement claim.

    Authors: We agree that providing an explicit construction of such parameters would clarify the presentation and strengthen the central claims. The noncritical regime is defined in the manuscript by a strict inequality on the extrapolation parameters relative to the step-size sequence (see, e.g., the condition (3.5) in the paper). This condition can be satisfied independently of the specific problem data by selecting the Nesterov-type extrapolation parameters with a sufficiently slow decay, for instance by taking α_k = 1 - c/k^β with β ∈ (0,1) and c small enough. We will add a new remark or subsection in the revised manuscript that explicitly constructs such a sequence and verifies that it satisfies both the noncritical regime and the assumptions required for the convergence theorems. This construction is problem-independent and works for any convex differentiable objective satisfying the standing assumptions. revision: yes

Circularity Check

0 steps flagged

No significant circularity in convergence and rate proofs

full rationale

The paper proposes accelerated augmented Lagrangian methods motivated by an inertial dynamical system, then proves primal-dual convergence to a saddle point and accelerated estimates (O(1/k^2) or o(1/k^2) in the noncritical regime) under stated parameter conditions on the Nesterov extrapolation parameters. These results rest on direct analysis of the discrete schemes and the continuous system rather than on any quantity defined in terms of itself, any fitted parameter renamed as a prediction, or any load-bearing self-citation chain. No equations or claims reduce by construction to their inputs; the derivation is self-contained against external mathematical benchmarks.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claims rest on standard domain assumptions of convexity and differentiability together with the existence of suitable extrapolation parameters; no new entities are postulated.

free parameters (1)
  • Nesterov extrapolation parameters
    The methods rely on specific choices of these parameters to obtain both convergence and the improved little-o rates; the abstract refers to them as 'suitable parameter conditions' without explicit fitting procedure.
axioms (1)
  • domain assumption Objective function is convex and continuously differentiable (or smooth)
    Invoked to define the problem class and to justify the implicit and partially explicit schemes.

pith-pipeline@v0.9.0 · 5681 in / 1302 out tokens · 45519 ms · 2026-05-20T04:46:35.554917+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

48 extracted references · 48 canonical work pages · 1 internal anchor

  1. [1]

    Adil, D., Kyng, R., Peng, R., Sachdeva, S.: Fast algorithms forℓp-regression. J. ACM 71(5), 1–45 (2024)

  2. [2]

    Attouch, H., Boţ, R.I., Csetnek, E.R.: Fast optimization via inertial dynamics with closed-loop damping. J. Eur. Math. Soc. 25, 1985–2056 (2023)

  3. [3]

    Attouch, H., Peypouquet, J.: The rate of convergence of Nesterov’s accelerated forward-backward method is actually faster than1/k2. SIAM J. Optim. 26, 1824–1834 (2016)

  4. [4]

    Attouch, H., Chbani, Z., Riahi, H.: Fast proximal methods via time scaling of damped inertial dynamics. SIAM J. Optim., 29, 2227-2256 (2019)

  5. [5]

    Attouch, H., Chbani, Z., Peypouquet, J., Redont, P.: Fast convergence of inertial dynamics and algorithms with asymptotic vanishing viscosity. Math. Program. 168, 123–175 (2018)

  6. [6]

    28, 849–874 (2018)

    Attouch, H., Cabot, A.: Convergenceratesofinertialforward-backwardalgorithms.SIAMJ.Optim. 28, 849–874 (2018)

  7. [7]

    Attouch, H., Chbani, Z., Fadili, J., Riahi, H.: Fast convergence of dynamical ADMM via time scaling of damped inertial dynamics. J. Optim. Theory Appl. 193, 704–736 (2022)

  8. [8]

    Bai, J., Chen, Y., Dai, Y.H., Liu, Y.J.: A faster proximal-indefinite augmented Lagrangian method withO(1/k 2)convergence rate. J. Comput. Math. (to appear, 2026)

  9. [9]

    Bai, J., Jia, L., Peng, Z.: A new insight on augmented Lagrangian method with applications in machine learning. J. Sci. Comput. 99, 53 (2024)

  10. [10]

    SIAM, Philadelphia (2017)

    Beck, A.:First-Order Methods in Optimization. SIAM, Philadelphia (2017)

  11. [11]

    Athena Scientific, Belmont (2016)

    Bertsekas, D.P.:Nonlinear Programming, 3rd edn. Athena Scientific, Belmont (2016)

  12. [12]

    Boţ, R.I., Nguyen, D.K.: Improved convergence rates and trajectory convergence for primal-dual dynamical systems with vanishing damping. J. Differential Equations 303, 369–406 (2021)

  13. [13]

    Boţ, R.I., Csetnek, E.R., Nguyen, D.K.: Fast augmented Lagrangian method in the convex regime with convergence guarantees for the iterates. Math. Program. 200, 147–197 (2023)

  14. [14]

    The iterates of Nesterov's accelerated algorithm converge in the critical regimes , year =

    Boţ, R.I., Fadili, J., Nguyen, D.K.: The iterates of Nesterov’s accelerated algorithm converge in the critical regimes. arXiv preprint arXiv:2510.22715 (2025)

  15. [15]

    Boyd, S., Parikh, N., Chu, E., Peleato, B., Eckstein, J.: Distributed optimization and statistical learning via the alternating direction method of multipliers. Found. Trends Mach. Learn. 2, 1–122 (2011)

  16. [16]

    Chambolle, A., Dossal, C.: On the convergence of the iterates of the fast iterative shrinkage/thresh- olding algorithm. J. Optim. Theory Appl. 166, 968–982 (2016)

  17. [17]

    arXiv preprint arXiv:2109.11537 (2021)

    Ghadiri, M., Peng, R., Vempala, S.S.: Fasterp-norm regression using sparsity. arXiv preprint arXiv:2109.11537 (2021)

  18. [18]

    He, B., Yuan, X.: On the acceleration of augmented Lagrangian method for linearly constrained optimization. Optim. Online (2010) 28

  19. [19]

    He, X., Hu, R., Fang, Y.P.: Convergence rates of inertial primal-dual dynamical methods for separable convex optimization problems. SIAM J. Control Optim. 59, 3278–3301 (2021)

  20. [20]

    He, X., Hu, R., Fang, Y.P.: Inertial accelerated primal-dual methods for linear equality constrained convex optimization problems. Numer. Algorithms, 90(4), 1669-1690 (2022)

  21. [21]

    Automatica 146, 110547 (2022)

    He, X., Hu, R., Fang, Y.P.: Fast primal-dual algorithm via dynamical system for a linearly con- strained convex optimization problem. Automatica 146, 110547 (2022)

  22. [22]

    Trajectory convergence and $o(t^{-2})$ rates for Nesterov accelerated primal-dual dynamics without Lipschitz gradient assumption

    He, X., Huang, N.J., Y.B. Xiao, Fang, Y.P.: Trajectory convergence ando(t −2)rates for Nes- terov accelerated primal-dual dynamics without Lipschitz gradient assumption. arXiv preprint arXiv:2605.18236 (2026)

  23. [23]

    He, X.: Accelerated primal-dual methods with adaptive parameters for composite convex optimiza- tion with linear constraints. Appl. Numer. Math. 203, 129–143 (2024)

  24. [24]

    He, X., Huang, N.J., Fang, Y.P.: Non-ergodic convergence rate of an inertial accelerated primal-dual algorithm for saddle point problems. Commun. Nonlinear Sci. Numer. Simul. 140, 108289 (2025)

  25. [25]

    He, X., Huang, N.J., Fang, Y.P.: Accelerated linearized alternating direction method of multipliers with Nesterov extrapolation. Commun. Nonlinear Sci. Numer. Simul., 109818 (2026)

  26. [26]

    Com- put

    He, X., Fang, Y.P.: Accelerated forward-backward algorithms with subgradient corrections. Com- put. Optim. Appl. 93, 121–156 (2026)

  27. [27]

    Huang, B., Ma, S., Goldfarb, D.: Accelerated linearized Bregman method. J. Sci. Comput. 54, 428–453 (2013)

  28. [28]

    Point convergence of nesterov’s accelerated gradient method: An ai-assisted proof.arXiv preprint arXiv:2510.23513, 2025

    Jang, U., Ryu, E.K.: Point convergence of Nesterov’s accelerated gradient method: An AI-assisted proof. arXiv preprint arXiv:2510.23513 (2025)

  29. [29]

    Kang, M., Yun, S., Woo, H., Kang, M.: Accelerated Bregman method for linearly constrainedℓ1-ℓ2 minimization. J. Sci. Comput. 56, 515–534 (2013)

  30. [30]

    Springer, Singapore (2020)

    Lin, Z., Li, H., Fang, C.:Accelerated Optimization for Machine Learning. Springer, Singapore (2020)

  31. [31]

    Luo, H.: A universal accelerated primal-dual method for convex optimization problems. J. Optim. Theory Appl. 201(1), 280–312 (2024)

  32. [32]

    Luo, H., Chen, L.: From differential equation solvers to accelerated first-order methods for convex optimization. Math. Program. 195, 735–781 (2022)

  33. [33]

    Luo, H., Zhang, Z.: A unified differential equation solver approach for separable convex optimiza- tion: splitting, acceleration and nonergodic rate. Math. Comp. 94, 3009–3041 (2025)

  34. [34]

    Soviet Math

    Nesterov, Y: A method for solving the convex programming problem with convergence rateO(1/k2). Soviet Math. Dokl. 27, 372–376 (1983)

  35. [35]

    Springer, New York (2004)

    Nesterov, Y.:Introductory Lectures on Convex Optimization. Springer, New York (2004)

  36. [36]

    32, 204–227 (2022)

    Sabach, S., Teboulle, M.: FasterLagrangian-basedmethodsinconvexoptimization.SIAMJ.Optim. 32, 204–227 (2022)

  37. [37]

    Shen, J., Mousavi, S.: Least sparsity ofp-norm based optimization problems withp >1. SIAM J. Optim. 28, 2721–2751 (2018) 29

  38. [38]

    Su, W., Boyd, S., Candès, E.J.: A differential equation for modeling Nesterov’s accelerated gradient method: theory and insights. J. Mach. Learn. Res. 17, 1–43 (2016)

  39. [39]

    Tang, T., Toh, K.C.: Self-adaptive ADMM for semi-strongly convex problems. Math. Program. Comput. 16, 113–150 (2024)

  40. [40]

    Tao, M., Yuan, X.: Accelerated Uzawa methods for convex optimization. Math. Comp. 86, 1821– 1845 (2017)

  41. [41]

    Tran-Dinh, Q., Zhu, Y.: Non-stationary first-order primal-dual algorithms with fast convergence rates. SIAM J. Optim. 30, 2866–2896 (2020)

  42. [42]

    Wibisono, A., Wilson, A.C., Jordan, M.I.: A variational perspective on accelerated methods in optimization. Proc. Natl. Acad. Sci. USA 113, E7351–E7358 (2016)

  43. [43]

    In: Proceedings of the International Conference on Machine Learning, pp

    Woodruff, D., Yasuda, T.: Sharper bounds forℓ p sensitivity sampling. In: Proceedings of the International Conference on Machine Learning, pp. 37238–37272. PMLR (2023)

  44. [44]

    Xie, Z., Yin, W., Wen, Z.: ODE-Based Learning to Optimize. Math. Program. (2025) DOI:10.1007/s10107-025-02303-3

  45. [45]

    Xu, Y.: Accelerated first-order primal-dual proximal methods for linearly constrained composite convex programming. SIAM J. Optim. 27, 1459–1484 (2017)

  46. [46]

    Zeng, X., Yi, P., Hong, Y., Xie, L.: Distributed continuous-time algorithms for nonsmooth extended monotropic optimization problems. SIAM J. Control Optim. 56, 3973–3993 (2018)

  47. [47]

    IEEE Trans

    Zeng, X., Lei, J., Chen, J.: Dynamical primal-dual Nesterov accelerated method and its application to network optimization. IEEE Trans. Automat. Control 68, 1760–1775 (2023)

  48. [48]

    Zhao, Y., Liao, X., He, X., Zhou, M., Li, C.: Acceleratedprimal-dualmirrordynamicsforcentralized and distributed constrained convex optimization problems. J. Mach. Learn. Res. 24, 1–59 (2023) 30