REVIEW 2 major objections 4 minor 1 cited by
New Homogeneous Solutions for the One-Phase Free Boundary Problem
T0 review · 2 major / 4 minor · reviewed 2026-08-04 · deepseek-v4-flash
Pith's one-line read For every large integer m, the paper constructs a domain on S^2 with m+2 boundary components whose first Laplace eigenvalue is exactly 2 and whose boundary satisfies the constant-gradient condition of the one-phase free boundary problem, br
desk verdict Serious construction paper: the 3D theorem is detailed and likely correct, the 4D theorem is deferred and needs more detail, but this deserves peer review. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The key mechanism is the LD solution φ = τ_0 Φ_0 + τ_2 Φ_2, a symmetric eigenfunction with logarithmic singularities at m equator points and two poles, whose singularity strengths are fixed by the vanishing-mismatch equations. The paper proves a bounded right inverse for the shifted Dirichlet-to-Neumann operator B on the oscillation subspace of boundary functions; this operator controls the dominant linear term in the normal derivative of the eigenfunction under domain perturbations, allowing a Schauder fixed point to close the nonlinear iteration uniformly in m.
What would settle it
For a specific moderately large m (say m=12), solve the linearized-doubling equation numerically to high precision, compute the mismatch vector M_Lφ, and check whether the radii τ_0, τ_2 given by equations (3.9)-(3.10) actually make both components vanish to the predicted order O(m^2 τ_0^3). A failure of the mismatch to vanish would invalidate the starting configuration.
Extended reading notes
Core claim
The central discovery is that minimal-surface 'doublings' of the equator in S^3 carry canonical solutions to the overdetermined eigenvalue problem when pulled back to the sphere. Specifically, the authors show that linearized-doubling (LD) solutions — singular eigenfunctions with logarithmic blow-up at prescribed points — provide approximate solutions whose mismatch can be tuned to zero, and that a perturbative scheme based on a shifted Dirichlet-to-Neumann operator turns these into exact solutions on domains that are small geodesic disks removed from S^2. The resulting domains are invariant under D_m x Z_2, have m+2 real-analytic boundary components, and are not rotationally symmetric.
Load-bearing premise
The entire iteration depends on the bounded right inverse for the shifted Dirichlet-to-Neumann operator B having operator norm independent of the discrete parameter m; if that norm grew with m, the error terms would overwhelm the linear control and the fixed point would not close.
Editorial extensions
If this is right
- There exist infinitely many non-rotationally-symmetric extremal domains for the first Laplace eigenvalue on S^2, contradicting the previously conjectured classification.
- The domains provide homogeneous solutions to the one-phase free boundary problem in R^3 with finite symmetry groups and arbitrarily many free-boundary components.
- The same construction works in S^3, producing domains with m^2 boundary components and giving an infinite family of homogeneous solutions in R^4.
- The boundary components are not constant-mean-curvature spheres, disproving a related conjecture about the shape of extremal boundary components.
- The examples are necessarily unstable for the Alt-Caffarelli functional, so they probe the class of non-minimizing free-boundary solutions where few explicit examples are known.
Reading between the lines
- The connection to minimal doublings suggests a general dictionary: any family of LD solutions with tunable singularities could yield new extremal domains in higher dimensions or other space forms.
- Since the construction leaves one free parameter after scaling, there may be a one-parameter family of solutions for each large m, not just isolated domains.
- The method likely extends to other eigenvalue constraints by shifting the linear operator accordingly, potentially producing extremal domains for higher eigenvalues.
- A numerical implementation for moderate m (say 10–20) could test the predicted scaling τ ~ e^{-√m/2} and verify λ_1 = 2 to high precision, providing a concrete check of the construction.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper constructs, for each sufficiently large integer m, a domain Ω_m⊂S^2 with m+2 real-analytic boundary components, invariant under D_m×Z_2, that admits a solution to the overdetermined problem (1.4), i.e. an extremal domain for the first Laplace eigenvalue with eigenvalue 2. The construction starts from Kapouleas-type LD solutions with singular set L_0∪L_2, solves the matching equations to obtain an approximate solution φ, develops an m-uniform linear theory for the shifted Dirichlet-to-Neumann operator on S^2\D, and closes a Schauder fixed point. The same scheme is claimed in dimension four, producing domains in S^3 with m^2 boundary components. The paper thereby answers a question of Jerison–Kamburov and disproves a conjecture of Souam and a related conjecture of Hong.
Significance. If the proofs are correct, Theorem 1.1 is a substantial result: it provides the first non-rotationally symmetric extremal domains in S^2 with finite isometry group, resolving an open question and a conjecture. The method connecting minimal-surface doublings to the one-phase free boundary problem is new and likely to be influential. The proof of Theorem 1.1 is largely self-contained and contains many explicit m-uniform estimates; in particular, the boundedness of the right inverse in Proposition 4.13 is supported by a detailed construction, contrary to the concern that it might hide m-dependence. The main weaknesses are an apparent error in the displayed matching equation (3.11), which is load-bearing for the asymptotic sizes of τ_0 and τ_2, and the abbreviated proof of the dimension-four theorem in Section 6.
major comments (2)
- [§3.4, Eq. (3.11)] As printed, equation (3.11) cannot be the correct matching equation. Substituting r=√(m/2)−(1/4)log m, the regime claimed in (i)(b), gives m/2−r^2≈(1/2)√(m/2)log m while the logarithmic term is ≈−(3/2)√(m/2)log m, so the left-hand side is ≈−√(m/2)log m, not zero. Deriving from (3.9)–(3.10) yields instead m/2−r^2+r log(e r/(2m e^{Φ'_0(p0)}))=0, or an equivalent form. The subsequent expression for ζ in (3.12) is consistent with the corrected equation but not with the printed one. Since the sizes of τ_0 and τ_2 feed into every later estimate, this must be corrected and the cancellation leading to (3.12) displayed.
- [§6 / Theorem 6.28] Theorem 1.2 is a central advertised result, but its proof is not written: the paper says it is 'essentially identical to that of Theorem 5.11', and several lemmas in Section 6 are deferred with 'obvious notational changes' (e.g. Lemma 6.18(iv), Proposition 6.19 Step 2, Proposition 6.20). The fixed-point argument is the heart of the construction; please provide the dimension-four analogue of Theorem 5.11's proof, or at least a precise point-by-point dictionary that verifies all constants are m-independent and that the operator B in (6.22) satisfies the same estimates used to close the Schauder argument.
minor comments (4)
- [§2.2, Lemma 2.6] The notation D_{2m} for a dihedral group of order 2m is nonstandard and conflicts with the use of D_m in Theorem 1.1. Please harmonize the notation (e.g. use D_m for the dihedral group of order 2m and G_m≅D_m×Z_2).
- [§4.2, Prop. 4.13 Step 2] Reference typo: '(6.23)' should be '(4.23)'. Similarly, in Prop. 5.10 the reference to '(6.31)' should be '(5.12)'.
- [§6] Several occurrences of S^2 should be S^3 in the dimension-four section: Prop. 6.19(i), Corollary 6.23(i), and Lemma 6.18's domain notation should be checked.
- [Introduction, §1 after Thm 1.1] The assertion that 'there is no solution of (1.4) arising in this way' for the simpler equator-only candidate is stated without proof or reference. Either supply a proof or mark it as a heuristic/observation.
Circularity Check
No significant circularity: the construction solves genuine matching equations and a fixed-point problem; reliance on prior LD solutions is an external dependency, not an assumed conclusion.
full rationale
The paper's central claim (Theorem 1.1) is an existence result for λ1-extremal domains in S^2 with m+2 boundary components. The derivation does not assume this conclusion. The approximate solution φ is obtained in Lemma 3.12 by solving the mismatch equations M_iφ = 0, which are nonlinear equations determining the radii τ0,τ2; these are not fitted parameters renamed as predictions. The final solution is obtained in Theorem 5.11 by a Schauder fixed point applied to the map N(w), with the operator B carrying the dominant linear term; Proposition 4.13 constructs the right inverse R via R = R̃(BR̃)^{-1} after proving ∥BR̃−I∥ ≤ C/√m in (4.24). This is a standard perturbation argument, not a definitional identity. The dependencies on Kapouleas/McGrath LD solutions [28,29,30] and Kapouleas–Zou [31] supply linear singular solutions of the Jacobi equation and are not equivalent to the extremal-domain conclusion. Some of these references are self-citations by the authors, but they are used for background linear elliptic facts (existence/uniqueness of LD solutions, estimates) that do not contain the theorem being proved. The skeptical concern about uniformity in m of the right-inverse bound is a genuine technical condition, but it is a correctness/verification issue, not circularity. Section 6 omits proofs for Theorem 6.28 with 'we don't repeat the details'; this is an omitted-detail concern, not circular reasoning. Overall, no circular step is exhibited; the proof is a genuine gluing/perturbation construction.
Assumptions & free parameters
assumptions (5)
- domain assumption Existence and uniqueness of G_m-symmetric LD solutions with prescribed configuration (Lemma 3.2)
- standard math Green's function estimates for L=Δ+2 on S^2 (Lemma 2.10) and for L=Δ+3 on S^3 (Lemma 6.7)
- standard math ODE facts for rotationally invariant solutions on S^3 (Lemma 6.9)
- standard math Schauder fixed point theorem and standard elliptic regularity / Fredholm alternative
- domain assumption Symmetry group G_m acts transitively on L_0 and L_2, forcing the eigenspace decomposition in Lemma 2.8
Cite this review
Pith. "Pith review of New Homogeneous Solutions for the One-Phase Free Boundary Problem." pith.science (2026). https://pith.science/paper/4THZ7ZY3
@misc{pith2026250909409,
author = {Pith},
title = {Pith review of: New Homogeneous Solutions for the One-Phase Free Boundary Problem},
year = {2026},
howpublished = {\url{https://pith.science/paper/4THZ7ZY3}},
note = {Machine review of arXiv:2509.09409}
}
abstract
For each sufficiently large integer $k$, we construct a domain in the round $2$-sphere with $k$ boundary components which is the link of a cone in $\mathbb{R}^3$ admitting a homogeneous solution to the one-phase free boundary problem. This answers a question of Jerison-Kamburov, and also disproves a conjecture of Souam left open in earlier work. The method exploits a new connection with minimal surfaces, which we also use to construct an infinite family of homogeneous solutions in dimension four.
Forward citations
Cited by 1 Pith paper
-
Topology of minimal surfaces in the sphere from capillarity
A capillary interpolation framework produces new minimal surfaces in spheres as non-trivial sphere bundles over base spaces including Stiefel manifolds, projective planes over division algebras, and Lie group quotient...
Reference graph
Works this paper leans on
-
[1]
Agmon, A
S. Agmon, A. Douglis, and L. Nirenberg. Estimates near the boundary for solutions of elliptic partial differential equations satisfying general boundary conditions. I.Comm. Pure Appl. Math., 12:623–727, 1959
1959
-
[2]
H. W. Alt and L. A. Caffarelli. Existence and regularity for a minimum problem with free boundary.J. Reine Angew. Math., 325:105–144, 1981
1981
-
[3]
Basulto and N
J. Basulto and N. Kamburov. One-phase free boundary solutions of finite Morse index. J. Differential Equations, 410:319–345, 2024
2024
-
[4]
Berestycki, L
H. Berestycki, L. A. Caffarelli, and L. Nirenberg. Monotonicity for elliptic equations in unbounded Lipschitz domains.Comm. Pure Appl. Math., 50(11):1089–1111, 1997. NEW SOLUTIONS FOR THE FREE BOUNDARY PROBLEM 43
1997
-
[5]
M. Berger. Sur les premi` eres valeurs propres des vari´ et´ es riemanniennes.Compositio Math., 26:129–149, 1973
1973
-
[6]
Bombieri, E
E. Bombieri, E. De Giorgi, and E. Giusti. Minimal cones and the Bernstein problem. Invent. Math., 7:243–268, 1969
1969
-
[7]
Brock and J
F. Brock and J. Prajapat. Some new symmetry results for elliptic problems on the sphere and in Euclidean space.Rend. Circ. Mat. Palermo (2), 49(3):445–462, 2000
2000
-
[8]
L. A. Caffarelli, D. Jerison, and C. E. Kenig. Global energy minimizers for free bound- ary problems and full regularity in three dimensions. InNoncompact problems at the intersection of geometry, analysis, and topology, volume 350 ofContemp. Math., pages 83–97. Amer. Math. Soc., Providence, RI, 2004
2004
Show all 55 references
-
[9]
Ciraolo and L
G. Ciraolo and L. Vezzoni. On Serrin’s overdetermined problem in space forms. Manuscripta Math., 159(3-4):445–452, 2019
2019
-
[10]
Dai and Y
G. Dai and Y. Zhang. Sign-changing solution for an overdetermined elliptic problem on unbounded domain.J. Reine Angew. Math., 803:267–293, 2023
2023
-
[11]
De Silva and D
D. De Silva and D. Jerison. A singular energy minimizing free boundary.J. Reine Angew. Math., 635:1–21, 2009
2009
-
[12]
Delay and P
E. Delay and P. Sicbaldi. Extremal domains for the first eigenvalue in a general compact Riemannian manifold.Discrete Contin. Dyn. Syst., 35(12):5799–5825, 2015
2015
-
[13]
El Soufi and S
A. El Soufi and S. Ilias. Domain deformations and eigenvalues of the Dirichlet Lapla- cian in a Riemannian manifold.Illinois J. Math., 51(2):645–666, 2007
2007
-
[14]
Enciso, A
A. Enciso, A. J. Fern´ andez, D. Ruiz, and P. Sicbaldi. A Schiffer-type problem for annuli with applications to stationary planar Euler flows.Duke Mathematical Journal, 174(6):1151 – 1208, 2025
2025
-
[15]
Engelstein, X
M. Engelstein, X. Fern´ andez-Real, and H. Yu. Graphical solutions to one-phase free boundary problems.J. Reine Angew. Math., 804:155–195, 2023
2023
-
[16]
Engelstein, L
M. Engelstein, L. Spolaor, and B. Velichkov. Uniqueness of the blowup at isolated singularities for the Alt-Caffarelli functional.Duke Math. J., 169(8):1541–1601, 2020
2020
-
[17]
J. M. Espinar and D. A. Mar ´ ın. An overdetermined eigenvalue problem and the critical catenoid conjecture.To appear, JEMS, arXiv:2310.06705, 2023
2023 arXiv
-
[18]
M. M. Fall, I. A. Minlend, and T. Weth. Unbounded periodic solutions to Serrin’s overdetermined boundary value problem.Arch. Ration. Mech. Anal., 223(2):737–759, 2017
2017
-
[19]
M. M. Fall, I. A. Minlend, and T. Weth. Serrin’s overdetermined problem on the sphere.Calc. Var. Partial Differential Equations, 57(1):Paper No. 3, 24, 2018
2018
-
[20]
M. M. Fall, I. A. Minlend, and T. Weth. The schiffer problem on the cylinder and on the 2-sphere.J. Eur. Math. Soc., 2025
2025
-
[21]
Gilbarg and N
D. Gilbarg and N. S. Trudinger.Elliptic partial differential equations of second order. Classics in Mathematics. Springer-Verlag, Berlin, 2001. Reprint of the 1998 edition
2001
-
[22]
Hauswirth, F
L. Hauswirth, F. H´ elein, and F. Pacard. On an overdetermined elliptic problem. Pacific J. Math., 250(2):319–334, 2011
2011
-
[23]
G. Hong. The singular homogeneous solutions to one phase free boundary problem. Proc. Amer. Math. Soc., 143(9):4009–4015, 2015
2015
-
[24]
Jerison and N
D. Jerison and N. Kamburov. Structure of one-phase free boundaries in the plane. Int. Math. Res. Not. IMRN, (19):5922–5987, 2016
2016
-
[25]
Jerison and N
D. Jerison and N. Kamburov. Free boundaries subject to topological constraints. Discrete Contin. Dyn. Syst., 39(12):7213–7248, 2019
2019
-
[26]
Jerison and O
D. Jerison and O. Savin. Some remarks on stability of cones for the one-phase free boundary problem.Geom. Funct. Anal., 25(4):1240–1257, 2015
2015
-
[27]
Kamburov and L
N. Kamburov and L. Sciaraffia. Nontrivial solutions to Serrin’s problem in annular domains.Ann. Inst. H. Poincar´ e C Anal. Non Lin´ eaire, 38(1):1–22, 2021
2021
-
[28]
Kapouleas
N. Kapouleas. Minimal surfaces in the round three-sphere by doubling the equatorial two-sphere, I.J. Differential Geom., 106(3):393–449, 2017. 44 C. HINES, J. KOLESAR, AND P. MCGRATH
2017
-
[29]
Kapouleas and P
N. Kapouleas and P. McGrath. Minimal surfaces in the round three-sphere by dou- bling the equatorial two-sphere, II.Comm. Pure Appl. Math., 72(10):2121–2195, 2019
2019
-
[30]
Kapouleas and P
N. Kapouleas and P. McGrath. Generalizing the linearized doubling approach, I: Gen- eral theory and new minimal surfaces and self-shrinkers.Camb. J. Math., 11(2):299– 439, 2023
2023
-
[31]
Kapouleas and J
N. Kapouleas and J. Zou. Minimal hypersurfaces inS 4(1) by doubling the equatorial S3.arXiv preprint arXiv:2405.18283, 2024
2024 arXiv
-
[32]
M. A. Karlovitz.Some solutions to overdetermined boundary value problems on sub- sets of spheres. ProQuest LLC, Ann Arbor, MI, 1990. Thesis (Ph.D.)–University of Maryland, College Park
1990
-
[33]
Karpukhin, R
M. Karpukhin, R. Kusner, P. McGrath, and D. Stern. Embedded minimal surfaces in S3 andB 3 via equivariant eigenvalue optimization.arXiv preprint arXiv:2402.13121, 2024
2024 arXiv
-
[34]
Kinderlehrer and L
D. Kinderlehrer and L. Nirenberg. Regularity in free boundary problems.Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4), 4(2):373–391, 1977
1977
-
[35]
Kriventsov and G
D. Kriventsov and G. S. Weiss. Rectifiability, finite Hausdorff measure, and com- pactness for non-minimizing Bernoulli free boundaries.Comm. Pure Appl. Math., 78(3):545–591, 2025
2025
-
[36]
Kumaresan and J
S. Kumaresan and J. Prajapat. Serrin’s result for hyperbolic space and sphere.Duke Math. J., 91(1):17–28, 1998
1998
-
[37]
Kusner and P
R. Kusner and P. McGrath. On the Canham problem: bending energy minimizers for any genus and isoperimetric ratio.Arch. Ration. Mech. Anal., 247(1):Paper No. 10, 14, 2023
2023
-
[38]
Lee and E
J. Lee and E. Yeon. A new approach to the Fraser-Li conjecture with the Weierstrass representation formula.Proc. Amer. Math. Soc., 149(12):5331–5345, 2021
2021
-
[39]
R. Molzon. Symmetry and overdetermined boundary value problems.Forum Math., 3(2):143–156, 1991
1991
-
[40]
Morabito
F. Morabito. Serrin’s overdetermined problem onS N ×R.J. Geom. Anal., 33(10):Pa- per No. 327, 17, 2023
2023
-
[41]
N. S. Nadirashvili and A. V. Penskoi. Free boundary minimal surfaces and overde- termined boundary value problems.J. Anal. Math., 141(1):323–329, 2020
2020
-
[42]
Pacard and P
F. Pacard and P. Sicbaldi. Extremal domains for the first eigenvalue of the Laplace- Beltrami operator.Ann. Inst. Fourier (Grenoble), 59(2):515–542, 2009
2009
-
[43]
A. G. Reznikov. Linearization and explicit solutions of the minimal surface equation. Publ. Mat., 36(1):39–46, 1992
1992
-
[44]
A. Ros, D. Ruiz, and P. Sicbaldi. Solutions to overdetermined elliptic problems in nontrivial exterior domains.J. Eur. Math. Soc. (JEMS), 22(1):253–281, 2020
2020
-
[45]
Schlenk and P
F. Schlenk and P. Sicbaldi. Bifurcating extremal domains for the first eigenvalue of the Laplacian.Adv. Math., 229(1):602–632, 2012
2012
-
[46]
D.-H. Seo. Sufficient symmetry conditions for free boundary minimal annuli to be the critical catenoid.arXiv preprint arXiv:2112.11877, 2021
2021 arXiv
-
[47]
J. Serrin. A symmetry problem in potential theory.Arch. Rational Mech. Anal., 43:304–318, 1971
1971
-
[48]
V. E. Shklover. Schiffer problem and isoparametric hypersurfaces.Rev. Mat. Iberoamericana, 16(3):529–569, 2000
2000
-
[49]
Sicbaldi
P. Sicbaldi. New extremal domains for the first eigenvalue of the Laplacian in flat tori.Calc. Var. Partial Differential Equations, 37(3-4):329–344, 2010
2010
-
[50]
Sicbaldi
P. Sicbaldi. Extremal domains of big volume for the first eigenvalue of the Laplace- Beltrami operator in a compact manifold.Ann. Inst. H. Poincar´ e C Anal. Non Lin´ eaire, 31(6):1231–1265, 2014
2014
-
[51]
J. Simons. Minimal varieties in riemannian manifolds.Ann. of Math. (2), 88:62–105, 1968. NEW SOLUTIONS FOR THE FREE BOUNDARY PROBLEM 45
1968
-
[52]
R. Souam. Schiffer’s problem and an isoperimetric inequality for the first buckling eigenvalue of domains onS 2.Ann. Global Anal. Geom., 27(4):341–354, 2005
2005
-
[53]
M. Traizet. Classification of the solutions to an overdetermined elliptic problem in the plane.Geom. Funct. Anal., 24(2):690–720, 2014
2014
-
[54]
G. S. Weiss. Partial regularity for a minimum problem with free boundary.J. Geom. Anal., 9(2):317–326, 1999
1999
-
[55]
D. Wiygul. Minimal surfaces in the 3-sphere by stacking Clifford tori.J. Differential Geom., 114(3):467–549, 2020. Department of Mathematics, North Carolina State University, Raleigh NC 27695 Email address:cthines@ncsu.edu Email address:pjmcgrat@ncsu.edu Email address:jnkolesa...
2020
Reviewed August 4, 2026 · model on record in the stance chip above.
Discussion (0). Sign in to comment.