REVIEW 2 major objections 6 minor 29 references
On polynomial inequalities for cone-volumes of polytopes
T0 review · 2 major / 6 minor · reviewed 2026-08-15 · deepseek-v4-flash
Pith's one-line read For any fixed matrix of facet normals, the cone-volume set of a polytope family is path-connected and semialgebraic.
desk verdict Semialgebraicity of cone-volume sets is a genuine advance and the proof essentially works; a small missing-closure error in Proposition 3.6 is easy to fix. 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 carrying object is the type-cone subdivision of $\mathbb{R}^m_{\ge 0}$ together with the sets $W_k(U)$ defined by the polynomial equations $\gamma_i=f_{k,i}(b)b_i/n$ and $v_k(b)=1$. On each type-cone, the volume and facet volumes of $P(U,b)$ are polynomials in $b$ of degree at most $n$, so $W_k(U)$ is semialgebraic; the semialgebraic projection property turns the union of their closures into $C_{\rm cv}(U)$. The subspace concentration polytope $P_{\rm scc}(U)$, a scaled matroid base polytope, supplies the geometric comparison set whose relative interior is contained in $C_{\rm cv}(U)$.
What would settle it
For a small $U$ (for example the five-vector pentagon of Example 5.3), eliminate the $b$-variables from the polynomial equations defining $W_k(U)$ with a quantifier-elimination routine; if the resulting projection has a boundary that is not a finite union of sets defined by polynomial equations, then $C_{\rm cv}(U)$ is not semialgebraic and Theorem 1.3 is false.
Extended reading notes
Core claim
On the paper's own terms, the central discovery is Theorem 1.3 combined with Proposition 2.10: for any $U\in U(n,m)$, the cone-volume set $C_{\rm cv}(U)$ is a semialgebraic set and is path-connected. The proof partitions the parameter space $b\in\mathbb{R}^m_{\ge 0}$ into finitely many type-cones; on each cone, the polytope volume and facet volumes vary polynomially in $b$, so the pairs (cone-volume vector, $b$) form a semialgebraic set $W_k(U)$, and projecting these sets to the cone-volume coordinate gives $C_{\rm cv}(U)$. The paper also characterizes when $C_{\rm cv}(U)$ coincides with the subspace concentration polytope $P_{\rm scc}(U)$: this happens exactly for centrally symmetric $U$ with $m=2n$, that is, for parallelepipeds.
Load-bearing premise
The proof depends on Lemma 3.1's claim that the parameter space of right-hand sides splits into finitely many cones on which polytope volume and facet volumes are polynomial in the right-hand side; if that finite polynomial stratification fails, the semialgebraic conclusion is not established.
Editorial extensions
If this is right
- For every $U$, $C_{\rm cv}(U)$ is path-connected and semialgebraic, so the discrete logarithmic Minkowski existence problem for fixed $U$ reduces to checking membership in a semialgebraic subset of the standard simplex.
- The degree bound of Corollary 3.4 places an explicit ceiling on the number and degree of the polynomial inequalities needed to describe $C_{\rm cv}(U)$.
- For all non-parallelepiped $U$, the subspace concentration condition is necessary but not sufficient; the sets $C_{\rm cv}(U)$ and $P_{\rm scc}(U)$ fail to coincide even though the relative interior of $P_{\rm scc}(U)$ lies inside $C_{\rm cv}(U)$.
- The decomposition $C_{\rm cv}(U)=\bigoplus_j (\mathrm{rg}(S_j)/n)C_{\rm cv}(S_j)$ over irreducible components yields dimension $m-d$ and explains how cone-volume sets of smaller systems combine.
Reading between the lines
- Because semialgebraic sets are closed under quantifier elimination, the polynomial data defining $W_k(U)$ can in principle be converted algorithmically into explicit polynomial inequalities for $C_{\rm cv}(U)$; the paper's degree bound says this is finite, though for large $m$ it will be impractical.
- The equality characterization suggests a natural numerical probe: for non-parallelepiped $U$, measure the Hausdorff distance between $C_{\rm cv}(U)$ and $P_{\rm scc}(U)$ for small $n,m$ to quantify how much of the cone-volume set is missed by the subspace concentration condition.
- Conjecture 5.2, that $\dim^*(S(U,\gamma))=d-1$, implies that for irreducible $U$ the right-hand side realizing a fixed strictly positive cone-volume vector is finite; testing this on the pentagon example and other small irreducible systems would either support or refute the conjecture.
- The matroid-base-polytope description of $P_{\rm scc}(U)$ means the subspace concentration condition can be checked through matroid flats and separators; known matroid algorithms for base-polytope membership could make verification of the condition practical for large $m$.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper studies, for a fixed matrix U in U(n,m) of outer unit normals, the cone-volume set C_cv(U) of all cone-volume vectors of volume-one polytopes P(U,b)={x: U^T x <= b}, b>=0. It defines a subspace concentration polytope P_scc(U), shows that a discrete measure satisfies the subspace concentration condition exactly when its weight vector lies in relint P_scc(U), and proves structural results about C_cv(U): it is path-connected (Proposition 2.10), it decomposes according to irreducible matroid components (Proposition 2.7), and it coincides with P_scc(U) only in the centrally symmetric parallelepiped case (Theorem 2.11). The main result is Theorem 1.3, asserting that C_cv(U) is a semialgebraic set. The proof constructs finitely many type-cones A_k(U) on whose interiors the polytopes are simple and strongly isomorphic and on which volume and facet volumes are polynomial (Lemma 3.1); it then defines semialgebraic sets W_k(U), proves that the graph of the volume-normalized cone-volume map is the union of their closures (Lemma 3.2), and applies the Tarski-Seidenberg projection theorem. An additional section gives explicit polynomial descriptions for planar polygons, and a final section discusses non-uniqueness of right-hand sides giving the same cone-volume vector.
Significance. If Theorem 1.3 is correct, it is a substantial step for the discrete logarithmic Minkowski problem: it replaces an open existence question with the study of a semialgebraic subset of the simplex, and the path-connectedness result provides qualitative information that was previously known only in the plane or for special polytopes. The proof is a clean direct construction from the definition of C_cv(U), using Tarski-Seidenberg rather than any fitting or assumed target result; the paper also gives a degree bound for the polynomial description and connects the subspace concentration conditions to matroid base polytopes, which is a useful geometric reformulation. The main caveat is that the central stratification Lemma 3.1 is imported from the literature in a compressed form, and one later proposition (Proposition 3.6) is false as stated, although it is not needed for the main theorem.
major comments (2)
- [§3, Lemma 3.1] Lemma 3.1 is the load-bearing input to Theorem 1.3, but its proof is only a citation to McMullen's representation theorem together with Schneider's Lemma 5.1.3. The clause that the type-cones A_k(U) can be chosen as m-dimensional cones with simple polytopes on their interiors is not automatic and needs a precise justification: a non-simple polytope such as a regular octahedron with its eight facet-normal directions shows that non-simplicity is a codimension-at-least-one condition, and one must explain why such polytopes lie only on boundaries of the maximal cones rather than in their interiors. Please state the exact theorem from [21] being used and give the argument that the maximal cones have simple interiors; without this, the polynomial equations defining W_k(U) are not established and Theorem 1.3 is unsupported.
- [§3, Proposition 3.6] Proposition 3.6 as stated is false: C_cv(U) is not equal to the union over k in I(U) of Pi(W_k(U)) without taking closures. For a simplex U in general position, C_cv(U)=conv{e_1,...,e_{n+1}} contains the vertices e_i, but for the unique k in I(U) every vector in Pi(W_k(U)) has all coordinates strictly positive, because b lies in the interior of the type-cone and all facet volumes are positive. The proof itself only shows that (gamma(U,b),b) lies in cl W_k(U), which does not imply membership in Pi(W_k(U)). Since Section 4 correctly uses the closure version, this error does not affect Theorem 1.3, but the proposition and its proof need to be corrected.
minor comments (6)
- [§2, proof of Proposition 2.7] In the direct-sum formula (2.10), both summands are written as P(S,b_S); the second factor should be P(\bar S,b_{\bar S}) with \bar S=U\setminus S.
- [§4] The text refers to "Corollary 3.6" when the intended reference is Proposition 3.6; please fix the cross-reference.
- [Throughout] There are several typos, including "genreral", "diemnsions", "uniquness", and "Tothisendlet"; a careful proofreading pass is needed.
- [§3, proof of Lemma 3.1] Equation (3.1) contains a double equals sign ("=="); it should be a single equality.
- [§2, Example 2.6] The vector (0,0,1,1,) contains a stray comma and should be (0,0,1,1)^T.
- [§5, Example 5.3] The computation with MomentPolynomialOpt.jl is presented as an approximate numerical solution; please indicate whether a rigorous certificate of finiteness was obtained or explicitly label the finding as numerical evidence.
Circularity Check
No significant circularity: Theorem 1.3 is derived from external polynomial-volume stratification plus Tarski–Seidenberg; no fitted input or target result is used as input.
full rationale
The central claim, Theorem 1.3, is not circular. It follows from Lemma 3.1, which cites McMullen [21] and Schneider [24, Lemma 5.1.3] for the finite type-cone subdivision with polynomial volume and facet-volume functions; from the definition of the semialgebraic sets W_k(U) in (3.2); from Lemma 3.2 identifying the graph of the cone-volume map with the union of cl W_k(U); and from Tarski–Seidenberg projection. The cone-volume relation gamma_i = f_{k,i}(b) b_i / n is exactly the definition of a cone-volume vector, not a hidden input assumption equivalent to Ccv(U). No parameter is fitted to a data subset and then renamed a prediction. The only self-citation in the load-bearing vicinity is [15, Thm. I] in Proposition 2.10; it is used for path-connectedness, which is not required for Theorem 1.3, and it cites an independent published theorem rather than an assertion proved only in this paper. Thus it is not circular in the sense of the scoring rules. For completeness, I flag two non-circular correctness concerns that the manuscript itself or the derivation reveals: Lemma 3.1's claim that the interiors of full-dimensional type-cones consist of simple polytopes is the least explicit imported input and is not reproved here, and Proposition 3.6 appears to require closures, since boundary points such as simplex vertices lie in Ccv(U) but are not in the corresponding union of open projections. These are rigor issues, not circularity: the semialgebraic conclusion of Theorem 1.3 does not reduce to an equivalent of itself.
Assumptions & free parameters
assumptions (6)
- standard math McMullen's representation theorem: R^m_\ge 0 is subdivided into finitely many polyhedral type-cones A_k(U) such that on each interior the polytopes P(U,b) are strongly isomorphic, simple and n-dimensional.
- standard math Tarski-Seidenberg principle: the projection of a semialgebraic set is semialgebraic.
- standard math Schneider, Lemma 5.1.3: for a fixed combinatorial type, facet volumes are polynomials of degree n-1 in the support numbers.
- domain assumption Chen-Li-Zhu Theorem II: relint P_scc(U) is contained in C_cv(U) intersected with the positive simplex.
- domain assumption Henk-Linke Theorem I: a polytope with its centroid at the origin has a cone-volume vector in relint P_scc(U).
- standard math Positive basis theory: minimal positive bases of R^n have cardinality between n+1 and 2n, and maximal positive bases are of the form (V,-V) up to scaling.
Cite this review
Pith. "Pith review of On polynomial inequalities for cone-volumes of polytopes." pith.science (2026). https://pith.science/paper/NPPZICDS
@misc{pith2026250615370,
author = {Pith},
title = {Pith review of: On polynomial inequalities for cone-volumes of polytopes},
year = {2026},
howpublished = {\url{https://pith.science/paper/NPPZICDS}},
note = {Machine review of arXiv:2506.15370}
}
abstract
Motivated by the discrete logarithmic Minkowski problem we study for a given matrix $U\in\mathbb{R}^{n\times m}$ its cone-volume set $C_{\tt cv}(U)$ consisting of all the cone-volume vectors of polytopes $P(U,b)=\{ x\in\mathbb{R}^n : U^\intercal x\leq b\}$, $b\in\mathbb{R}^n_{\geq 0}$. We will show that $C_{\tt cv}(U)$ is a path-connected semialgebraic set which extends former results in the planar case or for particular polytopes. Moreover, we define a subspace concentration polytope $P_{\tt scc}(U)$ which represents geometrically the subspace concentration conditions for a finite discrete Borel measure on the sphere. This is up to a scaling the basis matroid polytope of $U$, and these two sets, $P_{\tt scc}(U)$ and $C_{\tt cv}(U)$, also offer a new geometric point of view to the discrete logarithmic Minkowski problem.
Figures
Reference graph
Works this paper leans on
-
[21]
Representations of polytopes and polyhedral sets
P. McMullen. “Representations of polytopes and polyhedral sets”.Ge- ometriae Dedicata2.1 (1973), 83–99.https://doi.org/10.1007/BF0 0149284
doi:10.1007/bf0 1973
-
[1]
M. Aigner. Combinatorial theory.Classics in Mathematics. Reprint of the 1979 original. Springer-Verlag, Berlin, 1997, viii+483.isbn: 3-540- 61787-6. https://doi.org/10.1007/978-3-642-59101-3
-
[2]
L. Baldi and B. Mourrain. MomentPolynomialOpt.jl. May 26, 2025. https://github.com/AlgebraicGeometricModeling/MomentPolyn omialOpt.jl?tab=readme-ov-file
work page 2025
-
[3]
An improved algorithm for quantifier elimination over real closed fields
S. Basu. “An improved algorithm for quantifier elimination over real closed fields”.Proceedings 38th Annual Symposium on Foundations of Computer Science. IEEE, 1997, 56–65. https://doi.org/10.1109 /SFCS.1997.646093
-
[4]
J.Bochnak,M.Coste,andM.-F.Roy.Realalgebraicgeometry.Springer,
-
[5]
The logarithmic Minkowski conjecture and theLp- Minkowski problem
K. J. Böröczky. “The logarithmic Minkowski conjecture and theLp- Minkowski problem”. Harmonic analysis and convexity. Berlin: De Gruyter, 2023, 83–118.isbn: 978-3-11-077537-2; 978-3-11-077538-9.h ttps://doi.org/10.1515/9783110775389-003 . real.mtak.hu/191 895/1/2210.00194v3.pdf
arXiv 2023
-
[6]
On the discrete logarith- mic Minkowski problem
K. J. Böröczky, P. Hegedus, and G. Zhu. “On the discrete logarith- mic Minkowski problem”.IMRN. International Mathematics Research Notices 2016.6 (2016), 1807–1838.issn: 1073-7928; 1687-0247/e.http s://doi.org/10.1093/imrn/rnv189
-
[7]
The cone volume measure of antipo- dal points
K. J. Böröczky and P. Hegedűs. “The cone volume measure of antipo- dal points”.Acta Mathematica Hungarica146.2 (2015), 449–465.issn: 0236-5294. https://doi.org/10.1007/s10474-015-0511-z
Show all 29 references
-
[8]
Cone-volume measure of general cen- tered convex bodies
K. J. Böröczky and M. Henk. “Cone-volume measure of general cen- tered convex bodies”.Advances in Mathematics286 (2016), 703–721. issn: 0001-8708. https://doi.org/10.1016/j.aim.2015.09.021
2016 doi
-
[10]
The logarithmic Minkowski problem for non-symmetricmeasures
S. Chen, Q. Li, and G. Zhu. “The logarithmic Minkowski problem for non-symmetricmeasures”. Transactions of the American Mathematical Society 371.4 (2019), 2623–2641. issn: 0002-9947. https://doi.org /10.1090/tran/7499. 22 REFERENCES
2019 doi
-
[11]
Submodular functions, matroids, and certain polyhe- dra
J. Edmonds. “Submodular functions, matroids, and certain polyhe- dra”. Combinatorial Structures and their Applications (Proc. Calgary Internat. Conf., Calgary, Alta., 1969). Gordon and Breach, New York- London-Paris, 1970, 69–87.https://doi.org/10.1007/3-540-3647 8-1_2
1969 doi
-
[12]
Matroid polytopes, nested sets and Bergman fans
E. Feichtner and B. Sturmfels. “Matroid polytopes, nested sets and Bergman fans”.Portugaliae Mathematica Nova Série62.4 (2005), 437–
2005
-
[13]
Shapes of polyhedra, mixed volumes and hyperbolic geometry
F. Fillastre and I. Izmestiev. “Shapes of polyhedra, mixed volumes and hyperbolic geometry”. Mathematika 63.1 (2017), 124–183. issn: 0025-5793. https://doi.org/10.1112/S002557931600019X
2017 doi
-
[14]
Grötschel, L
M. Grötschel, L. Lovasz, and A. Schrijver. Geometric algorithms and combinatorial optimization. Springer.Algorithms and Combinatorics. 2nd, 1993. isbn: 978-3-642-78242-8. https://doi.org/10.1007/978 -3-642-78240-4
1993 doi
-
[15]
Cone-volume measures of polytopes
M. Henk and E. Linke. “Cone-volume measures of polytopes”. Ad- vances in Mathematics253 (2014), 50–62.issn: 0001-8708.https://d oi.org/10.1016/j.aim.2013.11.015
2014 doi
- [16]
-
[17]
W. R. Inc. Mathematica, Version 14.0. Champaign, IL, 2024.https: //www.wolfram.com/mathematica
2024
-
[18]
The logarithmic Minkowski problem inR2
Y. Liu, X. Lu, Q. Sun, and G. Xiong. “The logarithmic Minkowski problem inR2”. Pure and Applied Mathematics Quarterly20.2 (2024), 869–902. https://doi.org/10.4310/PAMQ.2024.v20.n2.a5
2024 doi
-
[19]
A matroid polytope approach to sharp affine isoperimetric inequalities for volume decomposition functionals
Y. Liu, Q. Sun, and G. Xiong. “A matroid polytope approach to sharp affine isoperimetric inequalities for volume decomposition functionals” (2024). https://doi.org/10.48550/ARXIV.2404.09152
-
[20]
Sharp affine isoperimetric inequalities for the volume decomposition functionals of polytopes
Y. Liu, Q. Sun, and G. Xiong. “Sharp affine isoperimetric inequalities for the volume decomposition functionals of polytopes”.Advances in Mathematics 389 (2021), 107902. issn: 0001-8708. https://doi.org /10.1016/j.aim.2021.107902
2021
-
[22]
Subspace Concentration of Geometric Measures
H. Pollehn. “Subspace Concentration of Geometric Measures”. PhD thesis. Berlin, Feb. 2019
2019
-
[23]
On the properties of positive spanning sets and positive bases
R. G. Regis. “On the properties of positive spanning sets and positive bases”.Optimization and Engineering17.1(Sept.2015),229–262. issn: 1573-2924. https://doi.org/10.1007/s11081-015-9286-x
2015 doi
-
[24]
Schneider
R. Schneider. Convex bodies: the Brunn-Minkowski theory. expanded. Vol. 151. Encyclopedia of Mathematics and its Applications. Cam- bridge University Press, Cambridge, 2014, xxii+736.isbn: 978-1-107- 60101-7. https://doi.org/10.1017/CBO9781139003858. REFERENCES 23
2014 doi
-
[25]
The discrete planar L0-Minkowski problem
A. Stancu. “The discrete planar L0-Minkowski problem”.Advances in Mathematics 167.1 (2002), 160–174.issn: 0001-8708. https://doi.o rg/10.1006/aima.2001.2040
2002
-
[26]
The logarithmic Minkowski inequality for non-symmetric convex bodies
A. Stancu. “The logarithmic Minkowski inequality for non-symmetric convex bodies”.Advances in Applied Mathematics73.C (2016), 43–58. issn: 0196-8858. https://doi.org/10.1016/j.aam.2015.09.015
2016 doi
-
[27]
ThelogarithmicMinkowskiproblemforpolytopes
G.Zhu.“ThelogarithmicMinkowskiproblemforpolytopes”. Advances in Mathematics262 (2014), 909–931.issn: 0001-8708.https://doi.o rg/10.1016/j.aim.2014.06.004. Technische Universität Berlin, Institut für Mathematik, Sekr. MA4-1, Straße des 17. Juni 136, 10623 Berlin, Germany Email ...
2014 doi
-
[468]
https://doi.org/10.48550/arXiv.math/041 1260
issn: 0032-5155. https://doi.org/10.48550/arXiv.math/041 1260
-
[2013]
https://doi.org/10.1007/978-3-6 62-03718-8
isbn: 978-3-662-03718-8. https://doi.org/10.1007/978-3-6 62-03718-8
-
[2025]
org / 10
https : / / doi . org / 10 . 1090 / S0894 - 0347 - 2012 - 00741 - 3. https://arxiv.org/abs/2502.05430
2012 arXiv
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