Copositive Matrices with Ordered Off-Diagonal Entries
Pith reviewed 2026-05-20 17:13 UTC · model grok-4.3
The pith
Copositive matrices whose off-diagonal entries are nondecreasing in rows and columns can be decomposed as a positive semidefinite matrix plus a nonnegative matrix.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
If the off-diagonal entries of a copositive matrix are nondecreasing in rows and in columns, then it admits a decomposition into a positive semidefinite matrix plus a matrix with nonnegative entries. The authors apply this to show that a natural relaxation for optimizing quadratic forms over the simplex is tight for separable objective functions.
What carries the argument
The nondecreasing ordering condition on the off-diagonal entries, which is used to prove the existence of the PSD-plus-nonnegative decomposition for copositive matrices.
Load-bearing premise
The off-diagonal entries must be nondecreasing in every row and every column.
What would settle it
Construct a copositive matrix whose off-diagonal entries are nondecreasing in rows and columns but which cannot be expressed as the sum of a positive semidefinite matrix and a nonnegative matrix.
Figures
read the original abstract
We study copositive matrices which admit a decomposition into a sum of a positive semidefinite matrix and a matrix with nonnegative entries. Our main result shows that if the off-diagonal entries of a copositive matrix are nondecreasing in rows and in columns, then it admits such a decomposition. We apply this result to study optimization of quadratic forms over the standard simplex. As a corollary, we obtain that a natural relaxation of this problem is tight when the objective function is separable, resolving an open question of Dey and Kocuk.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proves that any copositive matrix whose off-diagonal entries are nondecreasing along each row and each column admits a decomposition as the sum of a positive semidefinite matrix and a nonnegative matrix. This structural result is applied to quadratic optimization over the standard simplex, yielding a corollary that a natural relaxation is tight for separable objective functions and thereby resolving an open question of Dey and Kocuk.
Significance. If the central theorem is correct, the result supplies a concrete, checkable sufficient condition for the PSD-plus-nonnegative decomposition of copositive matrices. The ordering hypothesis on off-diagonal entries is the key structural ingredient that enables an explicit construction, and the application to separable quadratic forms over the simplex directly answers a previously open question. This combination of a new sufficient criterion and a concrete optimization consequence strengthens the literature on copositive programming and nonconvex quadratic optimization.
minor comments (4)
- [§2] §2, Definition 2.3: the precise statement of the nondecreasing ordering (row-wise and column-wise) should be written with explicit inequalities rather than relying on the verbal description alone, to avoid any ambiguity when n>3.
- [Theorem 3.2] Theorem 3.2, proof of the decomposition: the construction of the PSD factor P and the nonnegative factor N is given, but the verification that P is indeed positive semidefinite for arbitrary n would benefit from an additional sentence confirming that the Schur complement or eigenvalue argument carries through without further restrictions.
- [Corollary 4.1] Corollary 4.1: the statement that the relaxation is tight for separable objectives is clear, yet the manuscript does not explicitly record the dual variables or the supporting hyperplane that certifies optimality; adding one line would make the tightness argument self-contained.
- [Figure 1] Figure 1: the caption should state the dimension n and the precise ordering used to generate the example matrix, so that readers can reproduce the numerical check.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of the manuscript, including the recognition that the central theorem provides a concrete sufficient condition for the PSD-plus-nonnegative decomposition and that the application resolves an open question of Dey and Kocuk. We appreciate the recommendation for minor revision.
Circularity Check
No significant circularity; derivation self-contained
full rationale
The paper establishes a sufficient condition for copositive matrices with nondecreasing off-diagonal entries (in rows and columns) to admit a PSD + nonnegative decomposition. This follows directly from the stated structural ordering hypothesis via a new proof, without any reduction of the central claim to fitted inputs, self-definitional equations, or load-bearing self-citations whose validity depends on the present work. The corollary resolving the open question of Dey and Kocuk is an application of the new theorem rather than its justification, and the derivation remains independent of prior results by the same authors.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption A matrix M is copositive if x^T M x >= 0 for every nonnegative vector x.
Lean theorems connected to this paper
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IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
If A=(a_i,j) in Cop_n and the off-diagonal entries of A are nondecreasing in rows and columns, i.e. a_i,j <= a_l,k when i≠j, l≠k, i<=l, and j<=k, then A in SPN_n (Theorem 1.1 / 3.5)
-
IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
Inductive framework on classes A_n satisfying (3.1.I-III) for copositivity implying SPN decomposition
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]
Tropical methods for building real space sextics with totally real tritangent planes , url =
Cueto, Maria Angelica and Len, Yoav and Markwig, Hannah and Ren, Yue , month = dec, year =. Tropical methods for building real space sextics with totally real tritangent planes , url =. doi:10.48550/arXiv.2512.24277 , abstract =
-
[2]
Breiding, Paul and Cobb, John and Englander, Aviva K. and Farnsworth, Nayda and Hauenstein, Jonathan D. and Henriksson, Oskar and Johnson, David K. and Garcia, Jordy Lopez and Mundayur, Deepak , month = jan, year =. Elimination. doi:10.48550/arXiv.2601.04383 , abstract =
work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2601.04383
-
[3]
Nicklasson, Lisa and Tsakiris, Manolis C. , month = jan, year =. The. doi:10.48550/arXiv.2502.18222 , abstract =
-
[4]
Sufficient and Necessary Conditions for Eckart-Young like Result for Tubal Tensors
Mor, Uria , month = jan, year =. Sufficient and. doi:10.48550/arXiv.2512.24405 , abstract =
work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2512.24405
-
[5]
Chen, Haibin and Chen, Yixuan and Wang, Chunyan and Fan, Qi , month = dec, year =. Tensor. doi:10.48550/arXiv.2512.24872 , abstract =
-
[6]
Elamaran, Athithan and Ferko, Christian and Scarlett, Sterling , month = dec, year =. Machine. doi:10.48550/arXiv.2512.23750 , abstract =
-
[8]
Linear Algebra and its Applications , author =
Projected tensor-tensor products for efficient computation of optimal multiway data representations , volume =. Linear Algebra and its Applications , author =. 2026 , keywords =. doi:10.1016/j.laa.2025.09.018 , abstract =
-
[9]
Nature Methods , author =. 2020 , note =. doi:10.1038/s41592-019-0686-2 , abstract =
-
[10]
Dinh, N. and Goberna, M. A. and Long, D. H. and Volle, M. , month = dec, year =. Robust generalized. doi:10.48550/arXiv.2512.22561 , abstract =
-
[11]
di and Langer, Lars-Luca , month = dec, year =
Dio, Philipp J. di and Langer, Lars-Luca , month = dec, year =. Characterization of. doi:10.48550/arXiv.2512.22584 , abstract =
-
[13]
Mathematics of Operations Research , author =
Exploiting symmetries in. Mathematics of Operations Research , author =. 2013 , note =. doi:10.1287/moor.1120.0558 , abstract =
-
[14]
Journal of the London Mathematical Society , author =
Polarization and. Journal of the London Mathematical Society , author =. 2025 , note =. doi:10.1112/jlms.70319 , abstract =
-
[15]
Marchetti, Giovanni Luca and Connelly, Erin and Breiding, Paul and Kohn, Kathlén , month = dec, year =. Critical. doi:10.48550/arXiv.2512.21029 , abstract =
-
[16]
Graziani, Giacomo , month = dec, year =. On the. doi:10.48550/arXiv.2512.21016 , abstract =
-
[17]
Henrion, Didier , month = dec, year =. Solving. doi:10.48550/arXiv.2512.19141 , abstract =
-
[18]
Finkel, Bella and Rodriguez, Jose Israel , month = dec, year =. The. doi:10.48550/arXiv.2512.18521 , abstract =
-
[19]
A homogeneous geometry of low-rank tensors , url =
Jacobsson, Simon , month = dec, year =. A homogeneous geometry of low-rank tensors , url =. doi:10.48550/arXiv.2512.13594 , abstract =
-
[20]
Kirk, Nathan and Gvozdanović, Ivan and Petrović, Sonja , month = dec, year =. Multilevel. doi:10.48550/arXiv.2505.04062 , abstract =
- [21]
-
[22]
Global optimization of low-rank polynomials , url =
Gaggioli, Llorenç Balada and Henrion, Didier and Korda, Milan , month = dec, year =. Global optimization of low-rank polynomials , url =. doi:10.48550/arXiv.2512.08394 , abstract =
-
[23]
Orevkov, S. Yu and Puchkova, N. D. , month = dec, year =. On mutual arrangements of a plane real curve relative to an \. doi:10.48550/arXiv.2512.06907 , abstract =
-
[24]
Borovik, Viktoriia and Friedman, Hannah and Hoşten, Serkan and Pfeffer, Max , month = dec, year =. Numerical. doi:10.48550/arXiv.2512.06939 , abstract =
-
[25]
Feliu, Elisenda and Ferrer, Joan and Telek, Máté L. , month = dec, year =. Copositivity, discriminants and nonseparable signed supports , url =. doi:10.48550/arXiv.2512.07373 , abstract =
-
[26]
Powers, Victoria , year =. Certificates of. doi:10.1007/978-3-030-85547-5 , keywords =
-
[27]
Wang, Jie and Hu, Liangbing and Xia, Bican , month = dec, year =. A. doi:10.48550/arXiv.2512.04406 , abstract =
-
[28]
Algebraic Statistics , author =
Logarithmic. Algebraic Statistics , author =. 2021 , pages =. doi:10.2140/astat.2021.12.75 , language =
-
[29]
Journal of Pure and Applied Algebra , author =
Real tropicalization and negative faces of the. Journal of Pure and Applied Algebra , author =. 2024 , keywords =. doi:10.1016/j.jpaa.2023.107564 , abstract =
-
[30]
Journal of Symbolic Computation , author =
Viro's patchworking and the signed reduced. Journal of Symbolic Computation , author =. 2026 , pages =. doi:10.1016/j.jsc.2025.102462 , language =
-
[31]
Transactions of the American Mathematical Society , author =
Tropicalization of graph profiles , copyright =. Transactions of the American Mathematical Society , author =. doi:10.1090/tran/8643 , abstract =
-
[32]
International Mathematics Research Notices , author =
Symmetric. International Mathematics Research Notices , author =. 2025 , pages =. doi:10.1093/imrn/rnaf277 , abstract =
-
[33]
Linear Algebra and its Applications , author =
(. Linear Algebra and its Applications , author =. 2026 , pages =. doi:10.1016/j.laa.2025.09.006 , language =
-
[34]
Annales de l'Institut Fourier , author =
Return of the plane evolute , volume =. Annales de l'Institut Fourier , author =. 2025 , pages =. doi:10.5802/aif.3703 , abstract =
-
[35]
Advances in Mathematics , author =
Wondertopes , volume =. Advances in Mathematics , author =. 2025 , pages =. doi:10.1016/j.aim.2025.110516 , language =
-
[36]
Faust, Matthew and Robinson, Jonah and Sottile, Frank , month = dec, year =. The. doi:10.48550/arXiv.2512.01226 , abstract =
-
[37]
Lee, Kisun , month = dec, year =. A priori bounds for certified. doi:10.48550/arXiv.2512.01355 , abstract =
-
[38]
Dressler, Mareike and Liao, Hongzhi and Roshchina, Vera , month = nov, year =. Exposed extreme rays of the. doi:10.48550/arXiv.2512.00348 , abstract =
-
[39]
On finiteness properties of separating semigroup of real curve , url =
Magin, Matthew , month = nov, year =. On finiteness properties of separating semigroup of real curve , url =. doi:10.48550/arXiv.2511.18545 , abstract =
-
[40]
Klep, Igor and Magron, Victor and Metzlaff, Tobias and Wang, Jie , month = nov, year =. Exploiting. doi:10.48550/arXiv.2511.18019 , abstract =
-
[41]
Zalar, Aljaž and Zobovič, Igor , month = nov, year =. Matricial. doi:10.48550/arXiv.2511.19247 , abstract =
-
[42]
Carathéodory number of homogeneous convex cones , url =
Chua, Chek Beng , month = nov, year =. Carathéodory number of homogeneous convex cones , url =. doi:10.48550/arXiv.2511.17051 , abstract =
-
[43]
ACM Communications in Computer Algebra , author =
Towards. ACM Communications in Computer Algebra , author =. 2024 , pages =. doi:10.1145/3717582.3717590 , abstract =
-
[44]
Gonska, Bernd and Ziegler, Günter M. , month = nov, year =. Inscribable stacked polytopes , url =. doi:10.48550/arXiv.1111.5322 , abstract =
work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.1111.5322
-
[45]
Finite convergence and minimizer extraction in moment relaxations with correlative sparsity , url =
Fantuzzi, Giovanni and Fuentes, Federico , month = nov, year =. Finite convergence and minimizer extraction in moment relaxations with correlative sparsity , url =. doi:10.48550/arXiv.2502.01410 , abstract =
-
[46]
Pratt, Elizabeth and Wang, Kexin , month = nov, year =. Avoidance. doi:10.48550/arXiv.2511.15888 , abstract =
-
[47]
SIAM Journal on Optimization , author =
Sampling. SIAM Journal on Optimization , author =. 2017 , note =. doi:10.1137/15M1052548 , abstract =
-
[48]
Notices of the American Mathematical Society , author =
Evolution of. Notices of the American Mathematical Society , author =. doi:10.1090/noti3280 , abstract =
-
[49]
Drton, Mathias and Gross, Elizabeth and Kosta, Dimitra and Leykin, Anton and Sullivant, Seth and Windisch, Daniel , month = nov, year =. Singular. doi:10.48550/arXiv.2511.15419 , abstract =
-
[50]
Mixing neural networks and the
Yahia, Ichrak Ben and Merlet, Jean-Pierre and Papegay, Yves , month = dec, year =. Mixing neural networks and the. 2021 20th. doi:10.1109/ICAR53236.2021.9659400 , abstract =
-
[51]
The reflection invariant bispectrum: signal recovery in the dihedral model , shorttitle =
Edidin, Dan and Katz, Josh , month = nov, year =. The reflection invariant bispectrum: signal recovery in the dihedral model , shorttitle =. doi:10.48550/arXiv.2408.09599 , abstract =
-
[52]
Unexpected loss of maximality: the case of
Kharlamov, Viatcheslav and Răsdeaconu, Rareş , month = nov, year =. Unexpected loss of maximality: the case of. doi:10.48550/arXiv.2303.02796 , abstract =
-
[53]
Mathematical Programming , author =
On standard quadratic programs with exact and inexact doubly nonnegative relaxations , volume =. Mathematical Programming , author =. 2022 , keywords =. doi:10.1007/s10107-020-01611-0 , abstract =
-
[54]
Schaefer, Elizabeth J. and Schaefer, Andrew J. , month = nov, year =. Maximizing the. doi:10.48550/arXiv.2511.08441 , abstract =
-
[55]
Dey, Santanu S. and Kocuk, Burak , year =. Convexification of a. doi:10.48550/ARXIV.2510.16595 , abstract =
-
[56]
Baldi, Lorenzo and Sinn, Rainer and Telek, Máté L. and Weigert, Julian , year =. Toric extensions of. doi:10.48550/ARXIV.2511.07342 , abstract =
-
[57]
Solving exact and noisy rank-one tensor completion with semidefinite programming , url =. arXiv.org , author =
-
[58]
Combinatorial. Mathematika , author =. 2020 , note =. doi:10.1112/mtk.12051 , abstract =
-
[59]
Research in the Mathematical Sciences , author =
On the topology of complex projective hypersurfaces , volume =. Research in the Mathematical Sciences , author =. 2024 , pages =. doi:10.1007/s40687-024-00435-0 , abstract =
-
[60]
Ouyang, Yi and Zhang, Chenhao , month = nov, year =. Generalized connectedness and. doi:10.48550/arXiv.2511.03277 , abstract =
-
[61]
On the normality of secant varieties
Ullery, Brooke , month = nov, year =. On the normality of secant varieties , url =. doi:10.48550/arXiv.1408.0865 , abstract =
work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.1408.0865
-
[62]
Lindsey, Kathryn and Menon, Govind , month = nov, year =. Regularization. doi:10.48550/arXiv.2511.01137 , abstract =
-
[63]
Hertrich, Christoph and Kober, Stefan and Loho, Georg , month = nov, year =. Arithmetic. doi:10.48550/arXiv.2511.02406 , abstract =
-
[65]
Numerical Algorithms , author =
Smooth connectivity in real algebraic varieties , volume =. Numerical Algorithms , author =. 2025 , mrnumber =. doi:10.1007/s11075-024-01952-3 , number =
-
[66]
Acta Universitatis Sapientiae, Mathematica , author =
Algebraic degree of optimization over a variety with an application to. Acta Universitatis Sapientiae, Mathematica , author =. 2025 , keywords =. doi:10.1007/s44426-025-00003-1 , abstract =
-
[67]
Symmetric ideals and invariant. Journal of Algebra , author =. 2026 , keywords =. doi:10.1016/j.jalgebra.2025.08.023 , abstract =
-
[68]
Algebraic degree of optimization over a variety with an application to
-
[69]
Collectanea Mathematica , author =
Convex hulls of surfaces in fourspace , volume =. Collectanea Mathematica , author =. 2025 , pages =. doi:10.1007/s13348-024-00444-w , abstract =
-
[70]
Lerario, Antonio , month = nov, year =. What is. doi:10.48550/arXiv.2411.04705 , abstract =
-
[71]
Logan, Adam and Várilly-Alvarado, Anthony and Zureick-Brown, David , month = oct, year =. The. doi:10.48550/arXiv.2510.24665 , abstract =
-
[72]
Deza, Anna and Hall, Georgina , month = oct, year =. Sum of. doi:10.48550/arXiv.2510.24550 , abstract =
-
[73]
Guan, Naillin and Hu, Yongle , month = oct, year =. Formalization of. doi:10.48550/arXiv.2510.24818 , abstract =
-
[74]
Barrilli, Enrica and Mourrain, Bernard and Taufer, Daniele , month = oct, year =. Generalized. doi:10.48550/arXiv.2510.25681 , abstract =
-
[75]
Huang, Daoji and Huh, June and Soskin, Daniel and Wang, Botong , month = oct, year =. Bounded ratios for. doi:10.48550/arXiv.2510.25030 , abstract =
-
[77]
Journal of Global Optimization , author =
Optimality and solutions for conic robust multiobjective programs , issn =. Journal of Global Optimization , author =. 2025 , keywords =. doi:10.1007/s10898-025-01552-y , abstract =
-
[78]
Weddle loci of net of quadrics and the rank of partially symmetric tensors , url =
Chiantini, Luca and Fagioli, Filippo , month = oct, year =. Weddle loci of net of quadrics and the rank of partially symmetric tensors , url =. doi:10.48550/arXiv.2510.16571 , abstract =
-
[79]
Pelleriti, Nico and Spiegel, Christoph and Liu, Shiwei and Martínez-Rubio, David and Zimmer, Max and Pokutta, Sebastian , month = oct, year =. Neural. doi:10.48550/arXiv.2510.13444 , abstract =
-
[80]
Hashemi, Baran and Pasque, Kurt and Teska, Chris and Yoshida, Ruriko , month = oct, year =. Tropical. doi:10.48550/arXiv.2505.17190 , abstract =
-
[81]
Levin, Eitan and Chandrasekaran, Venkat , month = oct, year =. Dimension-. doi:10.48550/arXiv.2307.04230 , abstract =
-
[83]
Chenal, Jules and Manzaroli, Matilde , month = oct, year =. Real. doi:10.48550/arXiv.2506.03745 , abstract =
-
[84]
Journal of Symbolic Computation , author =
What is numerical algebraic geometry? , volume =. Journal of Symbolic Computation , author =. 2017 , keywords =. doi:10.1016/j.jsc.2016.07.015 , abstract =
-
[85]
Bates, Daniel J. and Sommese, Andrew J. and Hauenstein, Jonathan D. and Wampler, Charles W. , month = jan, year =. Back. Numerically. doi:10.1137/1.9781611972702.bm , pages =
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