Some isoperimetric inequalities with respect to monomial weights
Pith reviewed 2026-05-25 00:58 UTC · model grok-4.3
The pith
Among smooth sets in the upper half-plane with fixed y^β measure, the y^α weighted perimeter is minimized by an explicit y-axis symmetric set.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We show that, among all smooth sets Ω in R²₊ with fixed weighted measure ∬_Ω y^β dx dy, the weighted perimeter ∫_{∂Ω} y^α ds achieves its minimum for a smooth set which is symmetric w.r.t. the y-axis, and is explicitly given.
What carries the argument
The explicit y-axis symmetric minimizer of the weighted perimeter under the weighted area constraint.
If this is right
- The minimizer is smooth and symmetric with respect to the y-axis.
- The construction yields an estimate for the weighted Cheeger constant.
- A lower bound follows for the first eigenvalue of a class of nonlinear problems.
Where Pith is reading between the lines
- The explicit form of the minimizer permits direct calculation of the optimal isoperimetric ratio under the stated exponent conditions.
- The symmetry conclusion may indicate how the same weighted perimeter behaves when the domain is restricted further or when the weights are applied in related variational problems.
Load-bearing premise
The result requires the sets to be smooth and the exponents to satisfy 0 ≤ α < β + 1 together with β ≤ 2α.
What would settle it
A smooth set in the upper half-plane whose weighted area equals that of the claimed minimizer but whose weighted perimeter is strictly smaller would falsify the minimality statement.
Figures
read the original abstract
We solve a class of isoperimetric problems on $\mathbb{R}^2_+ :=\left\{ (x,y)\in \mathbb{R} ^2 : y>0 \right\}$ with respect to monomial weights. Let $\alpha $ and $\beta $ be real numbers such that $0\le \alpha <\beta+1$, $\beta\le 2 \alpha$. We show that, among all smooth sets $\Omega$ in $\mathbb{R} ^2_+$ with fixed weighted measure $\iint_{\Omega } y^{\beta} dxdy$, the weighted perimeter $\int_{\partial \Omega } y^\alpha \, ds$ achieves its minimum for a smooth set which is symmetric w.r.t. to the $y$--axis, and is explicitly given. Our results also imply an estimate of a weighted Cheeger constant and a lower bound for the first eigenvalue of a class of nonlinear problems.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript solves a class of weighted isoperimetric problems in the upper half-plane R²₊. For real parameters satisfying 0 ≤ α < β + 1 and β ≤ 2α, it asserts that among all smooth sets Ω ⊂ R²₊ with fixed weighted measure ∬_Ω y^β dx dy, the weighted perimeter ∫_{∂Ω} y^α ds attains its minimum at an explicitly described smooth set that is symmetric with respect to the y-axis. The results are also used to bound the weighted Cheeger constant and to obtain a lower bound on the first eigenvalue of an associated class of nonlinear eigenvalue problems.
Significance. If the central claim holds, the explicit identification of the minimizer supplies a concrete, verifiable example of equality in a weighted isoperimetric inequality under monomial weights. The parameter restrictions are presented as the natural regime in which a smooth closed comparison curve exists, and the consequences for the Cheeger constant and nonlinear eigenvalues extend the utility of the result beyond the pure isoperimetric statement.
minor comments (2)
- The abstract states that the minimizer is 'explicitly given' but does not display the explicit form or the associated curvature equation; adding the explicit expression (or at least the ODE it satisfies) to the abstract or the first paragraph of the introduction would improve immediate readability.
- The restriction to smooth sets is stated clearly, yet the introduction could briefly indicate whether the same explicit set remains a minimizer (or at least a stationary point) in a larger class such as sets of finite weighted perimeter.
Simulated Author's Rebuttal
We thank the referee for the positive assessment and recommendation of minor revision. The referee's summary correctly reflects the scope and consequences of the results. No major comments appear in the report, so we have no points requiring rebuttal or clarification at this stage. Any minor suggestions will be incorporated in the revised manuscript.
Circularity Check
No significant circularity detected
full rationale
The paper proves a direct minimization theorem: among smooth sets of fixed weighted measure ∬_Ω y^β dx dy, the weighted perimeter ∫_{∂Ω} y^α ds is minimized by an explicitly described y-axis symmetric set, under the stated restrictions 0 ≤ α < β+1 and β ≤ 2α. This is a self-contained existence and characterization result in the calculus of variations; the minimizer is constructed independently (via the associated weighted curvature problem) rather than being defined in terms of the perimeter itself. No steps reduce by construction to fitted inputs, self-citations, or ansatzes smuggled from prior work by the same authors. The result stands as an independent theorem with explicit assumptions and does not rely on renaming known patterns or load-bearing self-references.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Existence of minimizers in the class of smooth sets for the weighted isoperimetric problem under the given parameter restrictions.
Reference graph
Works this paper leans on
-
[1]
E. Abreu, L.G. Fernandes , On existence and nonexistence of isoperimetric inequalities with different monomial weights. arXiv:1904.01441v2, 11 Apr 2019
- [2]
-
[3]
A. Alvino, F. Brock, F. Chiacchio, A. Mercaldo, M.R. Posteraro , On weighted isoperimetric inequalities with non-radial densities (2018), Appl. Anal. , to appear doi.org/10.1080/00036811.2018.1506106
- [4]
- [5]
- [6]
- [7]
- [8]
-
[9]
B. Brandolini, F. Della Pietra, C. Nitsch, C. Trombetti , Symmetry breaking in a constrained Cheeger type isoperimetric inequality. (English summary) ESAIM Control Optim. Calc. Var. 21 (2015), 359–371
work page 2015
- [10]
- [11]
- [12]
- [13]
- [14]
- [15]
-
[16]
A. Ca˜nete, M. Miranda Jr., D. Vittone , Some isoperimetric problems in planes with density. J. Geom. Anal. 20 (2010), no.2, 243–290
work page 2010
-
[17]
T. Carroll, A. Jacob, C. Quinn, R. Walters, The isoperimetric problem on planes with density. Bull. Aust. Math. Soc. 78 (2008), no.2, 177–197. SOME ISOPERIMETRIC INEQUALITIES WITH RESPECT TO MONOMIAL WEIGHTS 29
work page 2008
-
[18]
V. Caselles, M. Miranda jr, M. Novaga , Total variation and Cheeger sets in Gauss space. J. Funct. Anal. 259 (2010), 1491–1516
work page 2010
-
[19]
Castro, Hardy-Sobolev inequalities with monomial weights
H. Castro, Hardy-Sobolev inequalities with monomial weights. Ann. Mat. Pura Appl. (4) 196 (2017), no. 2, 579–598
work page 2017
-
[20]
G. R. Chambers, Proof of the Log-Convex Density Conjecture, arXiv:1311.4012v3, to appear in: Journal of the European Mathematics Society
work page internal anchor Pith review Pith/arXiv arXiv
-
[21]
J. Cheeger, A lower bound for the smallest eigenvalue of the Laplacian,Problems in analysis: A symposium in honor of Salomon Bochner (1970), 195–199
work page 1970
-
[22]
G. Csat´o, An isoperimetric problem with density and the Hardy Sobolev inequality in R2, Differential Integral Equations 28 (2015), no. 9-10, 971-988
work page 2015
-
[23]
J. Dahlberg, A. Dubbs, E. Newkirk, H. Tran , Isoperimetric regions in the plane with densityrp, New York J. Math. 16 (2010), 31-51
work page 2010
-
[24]
G. De Philippis, G. Franzina, A. Pratelli, Existence of isoperimetric sets with densities ”converging from below” on RN. J. Geom. Anal. 27 (2017), 1086–1105
work page 2017
-
[25]
Balls Isoperimetric in $\mathbb{R}^n$ with Volume and Perimeter Densities $r^m$ and $r^k$
L. Di Giosia, J. Habib, L. Kenigsberg, D. Pittman, W. Zhu , Balls Isoperimetric in Rn with Volume and Perimeter Densities rm and rk. (2019), arXiv:1610.05830v2
work page internal anchor Pith review Pith/arXiv arXiv 2019
-
[26]
A. Diaz, N. Harman, S. Howe, D. Thompson Isoperimetric problems in sectors with density. Adv. Geom. 12 (2012), 589-619
work page 2012
- [27]
- [28]
-
[29]
Howe, The Log-Convex Density Conjecture and vertical surface area in warped products
S. Howe, The Log-Convex Density Conjecture and vertical surface area in warped products. Adv. Geom. 15 (2015), 455-468
work page 2015
-
[30]
I.R. Ionescu, T. Lachand-Robert , Generalized Cheeger sets related to landslides. Calc. Var. Partial Differential Equations 23 (2005), 227–249
work page 2005
- [31]
-
[32]
A.V. Kolesnikov, R.I. Zhdanov , On isoperimetric sets of radially symmetric measures. Concentration, functional inequalities and isoperimetry, 123-154, Contemp. Math. 545, Amer. Math. Soc., Providence, RI, 2011
work page 2011
-
[33]
C. Maderna, S. Salsa , Sharp estimates for solutions to a certain type of singular elliptic boundary value problems in two dimensions. Applicable Analysis 12 (1981), no.4, 307–321
work page 1981
-
[34]
Maz’ja, Lectures on isoperimetric and isocapacitary inequalities in the theory of Sobolev spaces
V. Maz’ja, Lectures on isoperimetric and isocapacitary inequalities in the theory of Sobolev spaces. Heat kernels and analysis on manifolds, graphs, and metric spaces (Paris, 2002), 307– 340, Contemp. Math. 338, Amer. Math. Soc., Providence, RI, 2003
work page 2002
- [35]
-
[36]
Morgan, Manifolds with density
F. Morgan, Manifolds with density. Notices Amer. Math. Soc. 52 (2005), no.8, 853–858
work page 2005
-
[37]
Morgan, The Log-Convex Density Conjecture
F. Morgan, The Log-Convex Density Conjecture. Contemporary Mathematics 545 (2011), 209–211
work page 2011
- [38]
-
[39]
Parini, An introduction to the Cheeger problem
E. Parini, An introduction to the Cheeger problem. Surv. Math. Appl. 6 (2011), 9–21
work page 2011
-
[40]
A. Pratelli, G. Saracco , On the isoperimetric problem with double density. Nonlinear Anal. 177 (2018), 733–752. 30 A. AL VINO, F. BROCK, F. CHIACCHIO, A. MERCALDO, AND M.R. POSTERARO
work page 2018
-
[41]
Saracco, Weighted Cheeger sets are domains of isoperimetry
G. Saracco, Weighted Cheeger sets are domains of isoperimetry. Manuscripta Math. 156 (2018), no. 3-4, 371–381
work page 2018
discussion (0)
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