Lipschitz regularity for fractional p-Laplacian with coercive gradients
Pith reviewed 2026-05-10 17:11 UTC · model grok-4.3
The pith
Viscosity solutions to fractional p-Laplacian equations with coercive gradient nonlinearities are locally Lipschitz continuous under bounds on p.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Any viscosity solution u to the equation (-Δ_p)^s u(x) + H(x, ∇u) = f is locally Lipschitz continuous when p belongs to (1, 2/(1-s)) ∪ (1, m+1), with f Lipschitz continuous and H coercive. Subsolutions satisfy Hölder continuity, and when f vanishes and H does not depend on x the only bounded solution is identically zero for all m, p > 1.
What carries the argument
Viscosity solution framework for the fractional p-Laplacian with coercive gradient perturbation, relying on comparison principles and oscillation estimates to control the gradient.
If this is right
- Solutions to the equation acquire local Lipschitz regularity directly from the structure without additional assumptions on u.
- In the homogeneous case with x-independent H the equation forces every bounded solution to be zero.
- Subsolutions satisfy interior Hölder continuity estimates that hold independently of the full Lipschitz conclusion.
- The admissible range for p enlarges or shrinks according to the fractional order s and the growth exponent m of H.
Where Pith is reading between the lines
- The same comparison techniques might adapt to other nonlocal operators that possess a similar coercivity structure in the gradient term.
- The Liouville-type result for bounded solutions suggests possible extensions to entire-space problems or long-time asymptotics.
- Relaxing coercivity of H would likely produce counterexamples to Lipschitz regularity, testing the necessity of that hypothesis.
Load-bearing premise
The gradient term H must be coercive, the right-hand side f must be Lipschitz continuous, and p must lie inside the stated range relative to s and m so that the comparison and oscillation arguments close.
What would settle it
Construction of a non-Lipschitz viscosity solution for some p outside the given intervals, or for a non-coercive H, would disprove the Lipschitz claim.
read the original abstract
In this article, we study nonlinear nonlocal equations with coercive gradient nonlinearity of the form \[ (-\Delta_p)^s u(x) + H(x, \nabla u) = f, \] where $f$ is Lipschitz continuous. We show that any viscosity solution $u$ is locally Lipschitz continuous, provided \[ p \in \left(1, \frac{2}{1-s}\right) \cup (1, m+1). \] We also establish H\"older continuity of subsolutions. Furthermore, in the case $f=0$ and $H$ is independent of $x$, we prove that the equation admits only the trivial solution in the class of bounded solutions, for all $m, p \in (1,\infty)$.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript establishes local Lipschitz continuity for viscosity solutions of the nonlocal equation (-Δ_p)^s u + H(x, ∇u) = f, where f is Lipschitz continuous, under the explicit restriction p ∈ (1, 2/(1-s)) ∪ (1, m+1). It further proves Hölder continuity for subsolutions and shows that the homogeneous problem (f = 0, H independent of x) admits only the trivial bounded solution for all m, p > 1.
Significance. If the proofs are correct, the results extend regularity theory for fractional p-Laplacian equations to include coercive gradient nonlinearities, with explicit parameter ranges that indicate where comparison and oscillation estimates close. The uniqueness statement for the homogeneous case is notably broad, holding without further restrictions on m or p. These contributions would be useful for analyzing nonlocal equations with nonlinear drift terms.
minor comments (3)
- The abstract and introduction state the parameter restrictions clearly, but a brief remark on why the estimates fail for p outside the given range would improve readability.
- The definition of viscosity solutions should explicitly address how the nonlocal tail is controlled in the comparison principle arguments.
- Notation for the fractional p-Laplacian operator and the coercivity assumption on H could be recalled in the statement of the main theorems for self-contained reading.
Simulated Author's Rebuttal
We thank the referee for the positive assessment of our work and the recommendation for minor revision. No specific major comments appear in the report.
Circularity Check
No significant circularity; derivation self-contained via comparison principles
full rationale
The paper establishes Lipschitz regularity for viscosity solutions of the nonlocal equation via comparison principles and oscillation estimates that close under the stated restrictions on p relative to s and m. These restrictions are explicitly required for the estimates to hold and do not reduce any claimed result to a fitted parameter or self-defined quantity. The uniqueness result for the homogeneous case follows directly from the coercivity assumption on H without invoking self-citations as load-bearing premises. No step equates a prediction to its input by construction, and the central claims remain independent of any prior self-citation chain.
Axiom & Free-Parameter Ledger
axioms (2)
- domain assumption Viscosity solution definition for the fractional p-Laplacian with gradient nonlinearity
- domain assumption Coercivity of the gradient term H(x, ∇u)
Reference graph
Works this paper leans on
-
[1]
A. Arapostathis, A. Biswas, and L. Caffarelli. On uniqueness of solutions to viscous HJB equations with a subquadratic nonlinearity in the gradient. Comm. Partial Differential Equations, 44(12):1466–1480, 2019
work page 2019
-
[2]
G. Barles. A weak Bernstein method for fully nonlinear elliptic equations,Diff. and Integral Equations4(2), 241–262, 1991
work page 1991
- [3]
- [4]
-
[5]
Guy Barles, Shigeaki Koike, Olivier Ley, and Erwin Topp. Regularity results and large time behavior for integro- differential equations with coercive Hamiltonians. Calc. Var. Partial Differential Equations, 54(1):539–572, 2015
work page 2015
-
[6]
Guy Barles, Olivier Ley, and Erwin Topp. Lipschitz regularity for integro-differential equations with coercive Hamiltonians and application to large time behavior. Nonlinearity, 30(2):703–734, 2017
work page 2017
-
[7]
On unbounded solutions of ergodic problems inRm for viscous Hamilton-Jacobi equations
Guy Barles and Joao Meireles. On unbounded solutions of ergodic problems inRm for viscous Hamilton-Jacobi equations. Comm. Partial Differential Equations, 41(12):1985–2003, 2016
work page 1985
-
[8]
Guy Barles and Erwin Topp. Lipschitz regularity for censored subdiffusive integro-differential equations with superfractional gradient terms. Nonlinear Anal., 131:3–31, 2016
work page 2016
-
[9]
A. Bensoussan and J. Frehse. On Bellman equations of ergodic control inRn. J. Reine Angew. Math., 429:125– 160, 1992
work page 1992
-
[10]
Sur la généralisation du problème de Dirichlet
Serge Bernstein. Sur la généralisation du problème de Dirichlet. Math. Ann., 62(2):253–271, 1906
work page 1906
-
[11]
Sur la géenéralisation du problème de Dirichlet
Serge Bernstein. Sur la géenéralisation du problème de Dirichlet. Math. Ann., 69(1):82–136, 1910
work page 1910
- [12]
-
[13]
M.F. Bidaut-Véron, M. García-Huidobro, L. Véron. Local and global properties of solutions of quasilinear Hamilton-Jacobi equations, J. Func. Anal. 267: 3294-3331, 2014
work page 2014
-
[14]
M.F. Bidaut-Véron, M. García-Huidobro, L. Véron. Estimates of solutions of elliptic equations with a source reaction term involving the product of the function and its gradient, Duke Math. J. 168: 1487–1537, 2019
work page 2019
- [15]
-
[16]
A. Biswas and A. Sen. Improved Hölder regularity of fractionalpp, qq-Poisson equation with regular data, 2025
work page 2025
-
[17]
A. Biswas and E. Topp. Nonlocal ergodic control problem inRd,Math. Annalen390, 45–94, 2024
work page 2024
-
[18]
A. Biswas and E. Topp. Lipschitz regularity of fractionalp-Laplacian,Annals of PDE11, no. 27, 2025
work page 2025
-
[19]
V. Bögelein, F. Duzaar, N. Liao, and K. Moring. Gradient estimates for the fractionalp-Poisson equation,J. Math. Pures et Appl.204, appeared online, 2025 arXiv:2503.05903, 2025
-
[20]
V. Bögelein, F. Duzaar, N. Liao, G. Molica Bisci, and R. Servadei. Regularity for the fractionalp-Laplace equation,J. Func. Anal.289(9), 2025
work page 2025
-
[21]
Gradient regularity for (s,p) -harmonic functions, 2024
V. Bögelein, F. Duzaar, N. Liao, G. Molica Bisci, and R. Servadei. Gradient regularity ofps, pq-harmonic func- tions,Calc. Var. Partial Differential Equations, to appear, arXiv:2409.02012, 2024
-
[22]
L. Brasco and E. Lindgren. Higher Sobolev regularity for the fractionalp-Laplace equation in the superquadratic case,Adv. Math.304, 300–354, 2017
work page 2017
- [23]
-
[24]
I. Capuzzo Dolcetta, F. Leoni ,and A. Porretta. Hölder estimates for degenerate elliptic equations with coercive Hamiltonians,Trans. Am. Math. Soc., 362(9):4511–4536, 2010
work page 2010
-
[25]
A. Ciomaga, D. Ghilli, and E. Topp. Periodic homogenization for weakly elliptic Hamilton-Jacobi- Bellman equations with critical fractional diffusion,Comm. Partial Differential Equations, 47(1):1–38, 2022
work page 2022
-
[26]
M. Cirant and A. Goffi. On the Liouville property for fully nonlinear equations with superlinear first-order terms, “Proceedings of the Conference on Geometric and Functional Inequalities and Recent Topics in Nonlinear PDEs", Contemporary Mathematics, American Mathematical Society, 781 (2023)
work page 2023
-
[27]
M. Cirant and G. Verzini. Local Hölder and maximal regularity of solutions of elliptic equations with su- perquadratic gradient terms,Advances in Mathematics, Vol. 409, Part B, 2022, 108700
work page 2022
-
[28]
M. Cozzi. Regularity results and Harnack inequalities for minimizers and solutions of nonlocal problems: a unified approach via fractional De Giorgi classes,J. Func. Anal.272 , 4762–4837, 2017
work page 2017
-
[29]
L. M. Del Pezzo and A. Quaas, The fundamental solution of the fractionalp´Laplacian,NoDEA Nonlinear Differential Equations Appl.33, no. 3, Paper No. 62, 2026
work page 2026
-
[30]
A. Di Castro, T. Kuusi, and G. Palatucci. Nonlocal Harnack inequalities,J. Funct. Anal.267 (6), 1807–1836, 2014 24 ANUP BISW AS, ANIKET SEN, AND ER WIN TOPP
work page 2014
-
[31]
A. Di Castro, T. Kuusi, and G. Palatucci. Local behavior of fractionalp-minimizers,Ann. Inst. H. Poincaré Anal. Non Linéaire33 , 1279–1299, 2016
work page 2016
-
[32]
L. Diening, K. Kim, H.-S. Lee and S. Nowak. Higher differentiability for the fractionalp-Laplacian,Math. Annalen391, 5631–5693, 2025
work page 2025
-
[33]
L. Diening and S. Nowak. Calderón-Zygmund estimates for the fractionalp-Laplacian,Annals of PDE11, no. 6, 2025
work page 2025
-
[34]
R. Filippucci. Nonexistence of positive weak solutions of elliptic inequalities, Nonlinear Anal., 70 2903–2916, 2009
work page 2009
-
[35]
P. Garain and E. Lindgren. Higher Hölder regularity for the fractionalp-Laplace equation in the subquadratic case.Math. Annalen390, 5753–5792, 2024
work page 2024
-
[36]
D. Giovagnoli, D. Jesus and L. Silvestre.C1`α regularity for fractionalp-harmonic functions. ArXiv:2509.26565, 2025
-
[37]
A.Iannizzotto, S.Mosconi, andM.Squassina.Fineboundaryregularityforthedegeneratefractionalp-Laplacian, J. Funct. Anal.279, no. 8, 108659, 54 pp., 2020
work page 2020
-
[38]
H. Ishii and P. L. Lions. Viscosity solutions of fully non-linear second-order elliptic partial differential equations, J. Differential Equations83, No.1, 26–78, 1990
work page 1990
- [39]
-
[40]
J. Korvenpää, T. Kuusi and E Lindgren. Equivalence of solutions to fractionalp-Laplace type equations,J. Math. Pures Appl.132, 1–26, 2019
work page 2019
-
[41]
J. Korvenpää, T. Kuusi, and G. Palatucci. Hölder continuity up to the boundary for a class of fractional obstacle problems,Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl.27, no. 3, 355–367, 2016
work page 2016
-
[42]
P. L. Lions, Quelques remarques sur les problèmes elliptiques quasilinéaires du second ordre,J. Anal. Math.45: 234–254,1985
work page 1985
-
[43]
È. Mitidieri and S. I. Pokhozhaev. Absence of positive solutions for quasilinear elliptic problems inRN, Tr. Mat. Inst. Steklova, 227:192–222, 1999
work page 1999
-
[44]
È. Mitidieri and S. I. Pokhozhaev. A priori estimates and the absence of solutions of nonlinear partial differential equations and inequalities, Tr. Mat. Inst. Steklova, 234:1–384, 2001 Indian Institute of Science Education and Research-Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, INDIA. Emails:anup@iiserpune.ac.in, aniket.sen@students.iiserpune.ac.in...
work page 2001
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.