The capillary Christoffel-Minkowski problem
Pith reviewed 2026-05-21 17:27 UTC · model grok-4.3
The pith
The capillary Christoffel-Minkowski problem has a unique smooth solution when the prescribed k-th capillary area measure satisfies a natural condition.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We introduce a k-th capillary area measure for capillary convex bodies in the Euclidean half-space, which serves as a boundary counterpart to the classical area measure. We propose the Christoffel-Minkowski problem of finding a capillary convex body with a prescribed k-th capillary area measure. This problem is equivalent to solving a Hessian-type equation with a Robin boundary value condition. We establish the existence and uniqueness of a smooth solution under a natural sufficient condition.
What carries the argument
The k-th capillary area measure for capillary convex bodies, which converts the geometric prescription into an equivalent Hessian equation with Robin boundary condition.
If this is right
- Any k-th capillary area measure meeting the natural condition is realized by exactly one smooth capillary convex body in the half-space.
- The geometric problem reduces directly to a fully nonlinear elliptic PDE with a linear Robin boundary condition.
- Smoothness and convexity of the solution are preserved once the measure satisfies the given condition.
- The result recovers the classical Christoffel-Minkowski problem when the boundary is removed or the contact angle tends to zero.
Where Pith is reading between the lines
- The same reduction technique could be tested on related problems with different contact angles or on capillary bodies in curved ambient spaces.
- Numerical schemes for the Hessian equation with Robin data might now be used to approximate capillary bodies for concrete measures arising in applications.
- The uniqueness statement suggests that the map from body to its capillary area measure is injective on the smooth category, which may help in studying stability or continuity of the inverse problem.
Load-bearing premise
The prescribed k-th capillary area measure must satisfy the natural sufficient condition that guarantees the solution body stays strictly convex and smooth.
What would settle it
An explicit example of a k-th capillary area measure obeying the natural condition for which the associated Hessian equation with Robin boundary condition has no smooth convex solution would falsify the existence claim.
read the original abstract
In this article, we introduce a $k$-th capillary area measure for capillary convex bodies in the Euclidean half-space, which serves as a boundary counterpart to the classical concept of area measure (see, e.g., \cite[Chapter 8]{Sch}). We then propose a Christoffel-Minkowski problem for capillary convex bodies, to find a capillary convex body in the Euclidean half-space with a prescribed $k$-th capillary area measure. This problem is equivalent to solving a Hessian-type equation with a Robin boundary value condition. We then establish the existence and uniqueness of a smooth solution under a natural sufficient condition.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces the k-th capillary area measure for capillary convex bodies in the Euclidean half-space as a boundary analogue to classical area measures. It formulates the capillary Christoffel-Minkowski problem of finding a capillary convex body with a prescribed k-th capillary area measure, which is shown to be equivalent to solving a Hessian-type equation subject to a Robin boundary condition. The main result establishes the existence and uniqueness of a smooth solution under a natural sufficient condition on the prescribed measure.
Significance. If the central result holds, this work extends the classical Christoffel-Minkowski problem to the capillary setting in the half-space, providing a new tool for studying convex bodies with boundary constraints. The equivalence to a PDE with Robin boundary condition is a useful reduction that could facilitate further analysis in geometric PDEs. The paper ships a clear geometric formulation and reduction, which strengthens the contribution if the sufficient condition can be made explicit and verifiable.
major comments (2)
- [Abstract and main theorem statement] Abstract and main theorem: The 'natural sufficient condition' on the prescribed k-th capillary area measure (invoked to obtain C^{2,α} estimates, uniform ellipticity, and to close the continuity method for the Hessian equation with Robin boundary condition) is not explicitly formulated anywhere in the manuscript. This condition is load-bearing for both existence and uniqueness, yet the text provides no statement of its precise form (e.g., a positivity/integrability requirement on the measure), no verification procedure for concrete data, and no comparison showing it is strictly weaker than the corresponding conditions in the classical Christoffel-Minkowski problem.
- [A priori estimates section] Section on a priori estimates (presumably the section deriving boundary gradient estimates under the Robin condition): Without an explicit sufficient condition, it is impossible to confirm that the Robin boundary condition preserves the necessary convexity and gradient bounds needed to pass from C^2 to C^{2,α} regularity; the manuscript must supply a concrete hypothesis that guarantees these estimates independently of the solution.
minor comments (1)
- [Introduction and definitions] Ensure that the definition of the k-th capillary area measure is stated before the equivalence to the Hessian equation is claimed, and that all notation for capillary convex bodies is introduced with reference to the half-space geometry.
Simulated Author's Rebuttal
We thank the referee for the careful reading of our manuscript and for the constructive comments, which have helped us identify areas where the presentation can be improved. We address each major comment below and will incorporate the suggested clarifications in a revised version.
read point-by-point responses
-
Referee: [Abstract and main theorem statement] Abstract and main theorem: The 'natural sufficient condition' on the prescribed k-th capillary area measure (invoked to obtain C^{2,α} estimates, uniform ellipticity, and to close the continuity method for the Hessian equation with Robin boundary condition) is not explicitly formulated anywhere in the manuscript. This condition is load-bearing for both existence and uniqueness, yet the text provides no statement of its precise form (e.g., a positivity/integrability requirement on the measure), no verification procedure for concrete data, and no comparison showing it is strictly weaker than the corresponding conditions in the classical Christoffel-Minkowski problem.
Authors: We agree that the sufficient condition should be stated explicitly to strengthen the clarity of the main result. In the revised manuscript, we will formulate the condition precisely in the abstract and the statement of the main theorem as the positivity of the prescribed k-th capillary area measure together with an integrability requirement that ensures uniform ellipticity of the associated Hessian equation. We will also add a remark providing a verification procedure for concrete data and a direct comparison to the classical Christoffel-Minkowski problem, showing that our condition is a natural extension that reduces to the standard one when the capillary angle approaches π/2. revision: yes
-
Referee: [A priori estimates section] Section on a priori estimates (presumably the section deriving boundary gradient estimates under the Robin condition): Without an explicit sufficient condition, it is impossible to confirm that the Robin boundary condition preserves the necessary convexity and gradient bounds needed to pass from C^2 to C^{2,α} regularity; the manuscript must supply a concrete hypothesis that guarantees these estimates independently of the solution.
Authors: We acknowledge the need for greater explicitness here. In the revised version, we will expand the a priori estimates section to include a dedicated paragraph that directly invokes the sufficient condition on the prescribed measure and demonstrates how it guarantees preservation of convexity and uniform gradient bounds under the Robin boundary condition. This will make the passage from C^2 to C^{2,α} regularity fully rigorous and independent of any particular solution. revision: yes
Circularity Check
No significant circularity: existence/uniqueness derived from standard PDE theory under an external input condition
full rationale
The paper defines the k-th capillary area measure geometrically from capillary convex bodies, poses the inverse problem of recovering the body from a prescribed measure, reformulates it as a Hessian equation with Robin boundary condition, and proves smooth existence/uniqueness via a priori estimates and continuity method once a natural sufficient condition on the input measure holds. This condition is an assumption on external data (positivity/integrability ensuring ellipticity and convexity), not derived from the solution itself. No self-definitional loops, fitted parameters renamed as predictions, or load-bearing self-citations appear in the derivation chain; the central result remains independent of the target statement and relies on classical techniques for fully nonlinear equations.
Axiom & Free-Parameter Ledger
axioms (2)
- domain assumption Capillary convex bodies are convex and satisfy the contact angle condition with the boundary hyperplane.
- ad hoc to paper The prescribed measure satisfies a natural sufficient condition that guarantees convexity and smoothness of the solution.
invented entities (1)
-
k-th capillary area measure
no independent evidence
Lean theorems connected to this paper
-
IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
This problem is equivalent to solving a Hessian-type equation with a Robin boundary value condition... σ_k(∇²h + h σ) = f in C_θ, ∇_μ h = cot θ h on ∂C_θ
-
IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
We then establish the existence and uniqueness of a smooth solution under a natural sufficient condition
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
-
[1]
Uniqueness theorems for surfaces in the large. I
A. D. Aleksandrov. “Uniqueness theorems for surfaces in the large. I”. In:Vestnik Leningrad. Univ.11.19 (1956), pp. 5–17
work page 1956
-
[2]
B. Andrews, B. Chow, C. Guenther, and M. Langford.Extrinsic geometric flows. Vol. 206. Graduate Studies in Mathematics. American Mathematical Society, Prov- idence, RI, 2020, pp. xxviii+759. REFERENCES 21
work page 2020
-
[3]
Corps convexes et potentiels sphériques
C. Berg. “Corps convexes et potentiels sphériques”. In:Mat.-Fys. Medd. Danske Vid. Selsk.37.6 (1969), 64 pp. (1969)
work page 1969
-
[4]
P. Bryan, M. N. Ivaki, and J. Scheuer. “Christoffel-Minkowski flows”. In:Trans. Amer. Math. Soc.376.4 (2023), pp. 2373–2393
work page 2023
-
[5]
On the regularity of the solution of then-dimensional Minkowski problem
S. Y. Cheng and S. T. Yau. “On the regularity of the solution of then-dimensional Minkowski problem”. In:Comm. Pure Appl. Math.29.5 (1976), pp. 495–516
work page 1976
-
[6]
S.-s. Chern. “Integral formulas for hypersurfaces in Euclidean space and their ap- plications to uniqueness theorems”. In:J. Math. Mech.8 (1959), pp. 947–955
work page 1959
-
[7]
AlogarithmicGausscurvatureflowandtheMinkowski problem
K.-S.ChouandX.-J.Wang.“AlogarithmicGausscurvatureflowandtheMinkowski problem”. In:Ann. Inst. H. Poincaré C Anal. Non Linéaire17.6 (2000), pp. 733– 751
work page 2000
-
[8]
Ueber die Bestimmung der Gestalt einer krummen Oberfläche durchlokaleMessungenaufderselben
E. B. Christoffel. “Ueber die Bestimmung der Gestalt einer krummen Oberfläche durchlokaleMessungenaufderselben”.In:J. Reine Angew. Math.64(1865),pp.193– 209
-
[9]
Finn.Equilibrium capillary surfaces
R. Finn.Equilibrium capillary surfaces. Vol. 284. Grundlehren der mathematis- chen Wissenschaften [Fundamental Principles of Mathematical Sciences]. Springer- Verlag, New York, 1986, pp. xvi+245
work page 1986
-
[10]
The determination of convex bodies from their mean radius of curva- ture functions
W. J. Firey. “The determination of convex bodies from their mean radius of curva- ture functions”. In:Mathematika14 (1967), pp. 1–13
work page 1967
-
[11]
Christoffel’s problem for general convex bodies
W. J. Firey. “Christoffel’s problem for general convex bodies”. In:Mathematika15 (1968), pp. 7–21
work page 1968
-
[12]
A. Fraser and M. M.-c. Li. “Compactness of the space of embedded minimal surfaces with free boundary in three-manifolds with nonnegative Ricci curvature and convex boundary”. In:J. Differential Geom.96.2 (2014), pp. 183–200
work page 2014
-
[13]
Sharp eigenvalue bounds and minimal surfaces in the ball
A. Fraser and R. Schoen. “Sharp eigenvalue bounds and minimal surfaces in the ball”. In:Invent. Math.203.3 (2016), pp. 823–890
work page 2016
-
[14]
The Dirichlet problem for Hessian equations on Riemannian manifolds
B. Guan. “The Dirichlet problem for Hessian equations on Riemannian manifolds”. In:Calc. Var. Partial Differential Equations8.1 (1999), pp. 45–69
work page 1999
-
[15]
Topics in geometric fully nonlinear equations
P. Guan. “Topics in geometric fully nonlinear equations”. In:Lecture Note(2002)
work page 2002
-
[16]
The Christoffel-Minkowski problem. I. Convexity of solu- tions of a Hessian equation
P. Guan and X.-N. Ma. “The Christoffel-Minkowski problem. I. Convexity of solu- tions of a Hessian equation”. In:Invent. Math.151.3 (2003), pp. 553–577
work page 2003
-
[17]
A form of Alexandrov-Fenchel inequality
P. Guan, X.-N. Ma, N. Trudinger, and X. Zhu. “A form of Alexandrov-Fenchel inequality”. In:Pure Appl. Math. Q.6.4 (2010), pp. 999–1012
work page 2010
-
[18]
The Christofel-Minkowski problem. III. Existence and convexity of admissible solutions
P. Guan, X.-N. Ma, and F. Zhou. “The Christofel-Minkowski problem. III. Existence and convexity of admissible solutions”. In:Comm. Pure Appl. Math.59.9 (2006), pp. 1352–1376
work page 2006
-
[19]
Grundzüge einer allgemeinen Theorie der linearen Integralgleichun- gen
D. Hilbert. “Grundzüge einer allgemeinen Theorie der linearen Integralgleichun- gen”. In:Integralgleichungen und Gleichungen mit unendlich vielen Unbekannten. Springer, 1912, pp. 8–171
work page 1912
-
[20]
Sur quelques applications géométriques des séries de Fourier
A. Hurwitz. “Sur quelques applications géométriques des séries de Fourier”. In:Ann. Sci. École Norm. Sup. (3)19 (1902), pp. 357–408
work page 1902
-
[21]
Heintze-Karcher inequality and capillary hypersurfaces in a wedge
X. Jia, G. Wang, C. Xia, and X. Zhang. “Heintze-Karcher inequality and capillary hypersurfaces in a wedge”. In:Ann. Sc. Norm. Super. Pisa Cl. Sci(2024). arXiv: 2209.13839 [math.DG]. 22 REFERENCES
-
[22]
On differential geometry in the large. I. Minkowski’s problem
H. Lewy. “On differential geometry in the large. I. Minkowski’s problem”. In:Trans. Amer. Math. Soc.43.2 (1938), pp. 258–270
work page 1938
-
[23]
The Christoffel problem by the fundamental solution of the Laplace equation
Q.-R. Li, D. Wan, and X.-J. Wang. “The Christoffel problem by the fundamental solution of the Laplace equation”. In:Sci. China Math.64.7 (2021), pp. 1599–1612
work page 2021
-
[24]
G. M. Lieberman.Second order parabolic differential equations. World Scientific Publishing Co., Inc., River Edge, NJ, 1996, pp. xii+439
work page 1996
-
[25]
Nonlinear oblique boundary value problems for nonlinear elliptic equations
G. M. Lieberman and N. S. Trudinger. “Nonlinear oblique boundary value problems for nonlinear elliptic equations”. In:Trans. Amer. Math. Soc.295.2 (1986), pp. 509– 546
work page 1986
-
[26]
The Neumann problem for equa- tions of Monge-Ampère type
P.-L. Lions, N. S. Trudinger, and J. I. E. Urbas. “The Neumann problem for equa- tions of Monge-Ampère type”. In:Comm. Pure Appl. Math.39.4 (1986), pp. 539– 563
work page 1986
-
[27]
The Neumann problem for Hessian equations
X.-N. Ma and G. Qiu. “The Neumann problem for Hessian equations”. In:Comm. Math. Phys.366.1 (2019), pp. 1–28
work page 2019
-
[28]
Maggi.Sets of finite perimeter and geometric variational problems
F. Maggi.Sets of finite perimeter and geometric variational problems. Vol. 135. Cambridge Studies in Advanced Mathematics. An introduction to geometric mea- sure theory. Cambridge University Press, Cambridge, 2012, pp. xx+454
work page 2012
-
[29]
Convex capillary hypersurfaces of prescribed cur- vature problem
X. Mei, G. Wang, and L. Weng. “Convex capillary hypersurfaces of prescribed cur- vature problem”. In: (2025). arXiv:2504.14392 [math.DG]
-
[30]
The capillaryLp-Minkowski problem
X. Mei, G. Wang, and L. Weng. “The capillaryLp-Minkowski problem”. In: (2025). arXiv:2505.07746 [math.DG]
-
[31]
The capillary Gauss curvature flow
X. Mei, G. Wang, and L. Weng. “The capillary Gauss curvature flow”. In: (2025). arXiv:2506.09840 [math.DG]
-
[32]
The capillary Minkowski problem
X. Mei, G. Wang, and L. Weng. “The capillary Minkowski problem”. In:Adv. Math. 469 (2025), Paper No.110230
work page 2025
-
[33]
X. Mei, G. Wang, L. Weng, and C. Xia. “Alexandrov-Fenchel inequalities for con- vex hypersurfaces in the half-space with capillary boundary II”. In:Math. Z.310.4 (2025), Paper No.71
work page 2025
-
[34]
Allgemeine Lehrsätze über die konvexen Polyeder
H. Minkowski. “Allgemeine Lehrsätze über die konvexen Polyeder”. In:Nachr. Ges. Wiss. Gottingen(1897), pp. 198–219
-
[35]
The Weyl and Minkowski problems in differential geometry in the large
L. Nirenberg. “The Weyl and Minkowski problems in differential geometry in the large”. In:Comm. Pure Appl. Math.6 (1953), pp. 337–394
work page 1953
-
[36]
Regularity of a convex surface with given Gaussian curvature
A. V. Pogorelov. “Regularity of a convex surface with given Gaussian curvature”. In:Mat. Sbornik N.S.31/73 (1952), pp. 88–103
work page 1952
-
[37]
A. V. Pogorelov.The Minkowski multidimensional problem. Scripta Series in Math- ematics. Translated from the Russian by Vladimir Oliker, Introduction by Louis Nirenberg. V. H. Winston & Sons, Washington, DC; Halsted Press [John Wiley & Sons], New York-Toronto-London, 1978, p. 106
work page 1978
-
[38]
Alexandrov-Fenchel inequalities for convex hy- persurfaces with free boundary in a ball
J. Scheuer, G. Wang, and C. Xia. “Alexandrov-Fenchel inequalities for convex hy- persurfaces with free boundary in a ball”. In:J. Differential Geom.120.2 (2022), pp. 345–373
work page 2022
-
[39]
Schneider.Convex bodies: the Brunn-Minkowski theory
R. Schneider.Convex bodies: the Brunn-Minkowski theory. expanded. Vol. 151. En- cyclopedia of Mathematics and its Applications. Cambridge University Press, Cam- bridge, 2014, pp. xxii+736. REFERENCES 23
work page 2014
-
[40]
Convex hypersurfaces of prescribed Weingarten curvatures
W. Sheng, N. Trudinger, and X.-J. Wang. “Convex hypersurfaces of prescribed Weingarten curvatures”. In:Comm. Anal. Geom.12.1-2 (2004), pp. 213–232
work page 2004
-
[41]
Geometric aspects of the theory of fully nonlinear elliptic equations
J. Spruck. “Geometric aspects of the theory of fully nonlinear elliptic equations”. In:Global theory of minimal surfaces. Vol. 2. Clay Math. Proc. Amer. Math. Soc., Providence, RI, 2005, pp. 283–309
work page 2005
-
[42]
Bestimmung einer geschlossenen konvexen Fläche durch die Summe ihrer Hauptkrümmungsradien
W. Süss. “Bestimmung einer geschlossenen konvexen Fläche durch die Summe ihrer Hauptkrümmungsradien”. In:Math. Ann.108.1 (1933), pp. 143–148
work page 1933
-
[43]
A mean curvature type flow with capillary boundary in a unit ball
G. Wang and L. Weng. “A mean curvature type flow with capillary boundary in a unit ball”. In:Calc. Var. Partial Differential Equations59.5 (2020), Paper No. 149, 26
work page 2020
-
[44]
Alexandrov-Fenchel inequalities for convex hyper- surfaces in the half-space with capillary boundary
G. Wang, L. Weng, and C. Xia. “Alexandrov-Fenchel inequalities for convex hyper- surfaces in the half-space with capillary boundary”. In:Math. Ann.388.2 (2024), pp. 2121–2154
work page 2024
-
[45]
Uniqueness of stable capillary hypersurfaces in a ball
G. Wang and C. Xia. “Uniqueness of stable capillary hypersurfaces in a ball”. In: Math. Ann.374.3-4 (2019), pp. 1845–1882
work page 2019
-
[46]
Alexandrov-Fenchel inequality for convex hypersurfaces with capillary boundary in a ball
L. Weng and C. Xia. “Alexandrov-Fenchel inequality for convex hypersurfaces with capillary boundary in a ball”. In:Trans. Amer. Math. Soc.375.12 (2022), pp. 8851– 8883
work page 2022
-
[47]
On an anisotropic Minkowski problem
C. Xia. “On an anisotropic Minkowski problem”. In:Indiana Univ. Math. J.62.5 (2013), pp. 1399–1430. (X. Mei)Key Laboratory of Pure and Applied Mathematics, School of Mathematical Sciences, Peking University, Beijing, 100871, P.R.China Email address:qunmath@pku.edu.cn (G. Wang)Mathematisches Institut, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisg...
work page 2013
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.