alphaFeedback

WorksPhysics and Astronomy

Holographic entropy inequalities without unscaled contraction proofs

AI contributions
  • Anthropic Claude Opus 5.5
View details
Ancillary data
1 code link
View

Abstract

We show that a valid holographic entropy inequality can lack a proof by contraction until all its coefficients are multiplied by a common integer, even when it is balanced, that is, every party has the same total coefficient on both sides, or superbalanced, that is, this remains true after any party is exchanged with the purifier. Every facet of the holographic entropy cone other than subadditivity is superbalanced. A proof by contraction is a map between Boolean cubes that respects the terms in which each party occurs and does not increase weighted Hamming distances. A balanced seven-party inequality and a superbalanced six-party inequality fail at a single point of the cube. Six of their right-hand side terms correspond to the edges of two disjoint triangles of parties, and at that point an unscaled map would have to choose three of these edges that together touch all six vertices, which is impossible. The seven-party one has a proof after doubling. Superbalanced eight- and seven-party inequalities have no unscaled proof even on their realizable domains, the subsets of the cube on which a map already proves validity, and they keep this property when instances of the monogamy of mutual information are subtracted in five successive steps. Splitting further into valid inequalities leads to a superbalanced facet F7F_7 of the seven-party cone that we did not find in the literature. It has unscaled maps on its realizable domain, all of which break its symmetry. For star inequalities, whose left-hand side contains only single-party entropies, the least scaling is the least kk for which an explicit polytope contains a point with coordinates in 1kZ\frac1k\mathbb{Z}. From the weighing matrices of Alon and Vũ we obtain valid NN-party star inequalities whose least scaling exceeds N(1/4−ε)NN^{(1/4-\varepsilon)N} for every ε>0\varepsilon>0 and large NN, while every finite least scaling of an NN-party star inequality is below NN/2N^{N/2}. Non-existence rests on DRAT proofs, validity on exact rational maps or identities, and the facet property on 126126 explicit graph models, except for the star inequalities of arbitrary size, whose results rest on written proofs.

Introduction

In holographic theories the entropy of a boundary region is computed by the area of an extremal surface in the bulk, by the formula of Ryu and Takayanagi and its covariant extension [1, 2]. Beyond subadditivity and strong subadditivity [3], these entropies obey further linear inequalities, the first found being the monogamy of mutual information (MMI) [4], which also holds for the covariant formula under the assumptions of [5]. For NN parties AA, BB, CC, …\ldots and a purifier OO, the valid linear inequalities cut out the holographic entropy cone HECN⊂R2N−1\mathrm{HEC}_N \subset\mathbb{R}^{2^N-1}. Bao, Nezami, Ooguri, Stoica, Sully and Walter showed that HECN\mathrm{HEC}_N is a rational polyhedral cone and that it is the set of entropy vectors of graph models, weighted graphs in which the entropy of a set of parties is the weight of a minimal cut [6]. The cone is known completely for N≤5N \le5 [6, 7], and two infinite families of its facets are known [8, 9].

The main method for proving that a candidate inequality ∑lαlS(Il)≥∑rβrS(Jr)\sum_l \alpha_l S(I_l) \ge\sum_r \beta_r S(J_r) is valid is proof by contraction [6]. Each party has an occurrence word on each side, which records the terms that contain it. A contraction map sends the Boolean cube of the left-hand side to that of the right-hand side, maps occurrence words to occurrence words and does not increase weighted Hamming distances. Bao et al. showed that such a map proves the inequality, and proved the five-party facets in this way [6, 7]. The list of five-party facets was shown to be complete in [7]. Much work since has gone into understanding and constructing contraction maps [10, 11, 12, 13, 14, 15, 16, 17]; see also [18].

Whether a valid inequality has a contraction proof depends on how it is presented. A coefficient can be kept as a weight or split into unit copies of its term, on either side, and the whole inequality can be multiplied by a positive integer kk before a map is sought [6, 19, 16]. Bao, Furuya and Naskar claim that every valid holographic entropy inequality with rational coefficients has a contraction map, and in the arXiv version of their paper of 14 July 2026 they specify that a map may be sought for any presentation obtained by merging or expanding terms and by uniformly rescaling all coefficients [20]. The claim also appears, without that specification, in the PhD thesis of Naskar of 15 June 2026 [21]. Several recent works assume that the inequalities they study have contraction proofs [22, 23]. Grimaldi, Headrick, Hubeny and Shteyner remark that, empirically, when the fully split presentation of an inequality has no map, multiplying the inequality by an integer does not create one; their discussion concerns primitive, that is facet-defining, inequalities [16]. Whether the scaling is ever needed, and for which inequalities, is the subject of this paper.

An inequality is balanced if every party has the same total coefficient on both sides [6], and superbalanced if, in addition, every inequality obtained from it by exchanging a party with the purifier is balanced, a notion introduced in [24] and put in this form in [25]. He, Hubeny and Rangamani proved that every facet of HECN\mathrm{HEC}_N other than the instances of subadditivity is superbalanced [25]. For the facets at small NN we found no failure. For N≤4N \le4 every facet of HECN\mathrm{HEC}_N is an instance of subadditivity or MMI [6], and these have unscaled maps. Of the eight orbits of facets of HEC5\mathrm{HEC}_5 under relabelings [7], our computer search found an unscaled map on the full cube for a representative of each. These maps are not among our certificates, and nothing below uses them. This raises three questions. Does every valid balanced, or superbalanced, inequality have an unscaled contraction proof? If not, how large must the scaling be? And what happens at the facets?

We answer the first question in the negative for both classes, give partial answers to the second, and follow one failure to a facet. A map for an inequality QQ on a domain Ω⊆{0,1}L\Omega\subseteq\{0,1\}^{L} is an integer count map in the sense of Definition 2.6, that is, a contraction map of Bao et al. for the presentation with merged left-hand side and split right-hand side, which on the full cube is the most permissive unscaled presentation (§ 2.3). The domain is either the full cube or the realizable domain A(Q)\mathcal{A}(Q) of Definition 2.11, and kmin⁡A(Q)k_{\min}^{A}(Q) and kmin⁡Λ(Q)k_{\min}^{\Lambda}(Q) are the least kk for which kQkQ has a map on these domains (Definition 2.10). In this paper we give a proof of the following statement.

Theorem 1.1.

(a) The seven-party inequality B7∗B_7^* of (10) is balanced and valid. It has no map on the full cube and none on its realizable domain, and 2B7∗2B_7^* has a map on the full cube, so kmin⁡(B7∗)=kmin⁡A(B7∗)=2k_{\min}(B_7^*) = k_{\min}^{A}(B_7^*) = 2.

(b) The six-party inequality U6U_6 of (13) is superbalanced and valid. It has no map on the full cube and none on its realizable domain, and 2U62U_6 has a map on its realizable domain, so kmin⁡A(U6)=2k_{\min}^{A}(U_6) = 2. The eight-party inequality Q8Q_8 of (18) and the seven-party inequalities E0,…,E5E_0,\ldots,E_5 of § 4, where E0E_0 is obtained from 3Q83Q_8 by subtracting a positive multiple of a sum of instances of MMI and deleting a party, and each Es+1E_{s+1} from EsE_s by subtracting a positive multiple of a sum of instances of MMI, are superbalanced and valid. None of them has a map on the full cube or on its realizable domain.

(c) The seven-party superbalanced inequality F7F_7 of (22) defines a facet of HEC7\mathrm{HEC}_7, and this facet contains the face of HEC7\mathrm{HEC}_7 on which E0E_0 vanishes. The inequality F7F_7 has a map on its realizable domain, and no such map is equivariant under the stabilizer Stab⁡(F7)≅S3\operatorname{Stab}(F_7) \cong\mathcal{S}_3, that is, commutes with the relabelings that fix F7F_7 (Appendix § 8.§ 4).

(d) The inequality 3Q83Q_8 has no map on the full cube or on its realizable domain, and 2E02E_0, 2E12E_1, 2E32E_3 and 2E42E_4 have maps on the full cube, so kmin⁡(Es)=kmin⁡A(Es)=2k_{\min}(E_s) = k_{\min}^{A}(E_s) = 2 for s=0,1,3,4s = 0,1,3,4. For

every j≥0j \ge0, the star inequality DjD_j of § 6.3, on N=4j+7N = 4j + 7 parties, is valid and kmin⁡(Dj)=2j+2=2(N+1)/4k_{\min}(D_j) = 2^{j+2} = 2^{(N+1)/4}. The seven-party star inequality Z7Z_7 of (37) has kmin⁡(Z7)=8k_{\min}(Z_7) = 8. For every N≥3N \ge3 there is a valid NN-party star inequality QNQ_N, implied by subadditivity and not balanced, with kmin⁡(QN)<∞k_{\min}(Q_N) < \infty and log⁡2kmin⁡(QN)≥54log⁡2N−(54+ϵN)N\log_2 k_{\min}(Q_N) \ge\frac{5}{4}\log_2 N - \left(\frac{5}{4} + \epsilon_N\right)N with ϵN→0\epsilon_N \to0 as N→∞N \to\infty, and every valid NN-party star inequality QQ with kmin⁡(Q)<∞k_{\min}(Q) < \infty has kmin⁡(Q)≤2(N+1)(N+1)/22−N<NN/2k_{\min}(Q) \le2(N+1)^{(N+1)/2}2^{-N} < N^{N/2}.

Part (a) shows that balance does not guarantee an unscaled contraction proof. The failure is visible at a single point of the cube, where an integer map would need three edges of two disjoint triangles of parties that together touch all six vertices (§ 3). Part (b) shows that superbalance does not guarantee one either, already for six parties. The six-party inequality U6U_6 fails at a single point by the same argument (§ 4.1), and for the eight- and seven-party inequalities the failure persists when sums of instances of MMI, which have unscaled maps, are subtracted in five steps. For E0E_0, E1E_1, E3E_3 and E4E_4 it disappears after doubling, by part (d). Part (c) is the one place where we can follow a failure to a facet. There the facet has an unscaled map on its realizable domain, though only one that breaks its symmetry. Part (d) shows that the scaling needed for a valid inequality can grow faster than exponentially with NN. So far we know this only for star inequalities, which are implied by subadditivity and are not balanced (§ 6.5), and for them the least scaling, when finite, is below NN/2N^{N/2}. Our results are consistent with the claim of Bao, Furuya and Naskar in the form of their arXiv version of 14 July 2026 [20], and they show that the uniform rescaling allowed there cannot be dropped.

References

  1. [1]S. Ryu and T. Takayanagi, Holographic Derivation of Entanglement Entropy from the anti–de Sitter Space/Conformal Field Theory Correspondence, Phys. Rev. Lett. 96 (2006), 181602, https://doi.org/10.1103/PhysRevLett.96.181602; arXiv:hep-th/0603001.
  2. [2]V. E. Hubeny, M. Rangamani, and T. Takayanagi, A Covariant holographic entanglement entropy proposal, JHEP 07 (2007), 062, https://doi.org/10.1088/1126–6708/2007/07/062; arXiv:0705.0016.
  3. [3]M. Headrick and T. Takayanagi, A Holographic proof of the strong subadditivity of entanglement entropy, Phys. Rev. D 76 (2007), 106013, https://doi.org/10.1103/PhysRevD.76.106013; arXiv:0704.3719.
  4. [4]P. Hayden, M. Headrick, and A. Maloney, Holographic Mutual Information is Monogamous, Phys. Rev. D 87 (2013), no. 4, 046003, https://doi.org/10.1103/PhysRevD.87.046003; arXiv:1107.2940.
  5. [5]A. C. Wall, Maximin Surfaces, and the Strong Subadditivity of the Covariant Holographic Entanglement Entropy, Class. Quant. Grav. 31 (2014), no. 22, 225007, https://doi.org/10.1088/0264-9381/31/22/225007; arXiv:1211.3494.
  6. [6]N. Bao, S. Nezami, H. Ooguri, B. Stoica, J. Sully, and M. Walter, The Holographic Entropy Cone, JHEP 09 (2015), 130, https://doi.org/10.1007/JHEP09(2015)130; arXiv:1505.07839.
  7. [7]S. Hernández Cuenca, Holographic entropy cone for five regions, Phys. Rev. D 100 (2019), no. 2, 026004, https://doi.org/10.1103/PhysRevD.100.026004; arXiv:1903.09148.
  8. [8]B. Czech, S. Shuai, Y. Wang, and D. Zhang, Holographic entropy inequalities and the topology of entanglement wedge nesting, Phys. Rev. D 109 (2024), no. 10, L101903, https://doi.org/10.1103/PhysRevD.109.L101903; arXiv:2309.15145.
  9. [9]B. Czech, Y. Liu, and B. Yu, Two infinite families of facets of the holographic entropy cone, SciPost Phys. 17 (2024), 084, https://doi.org/10.21468/SciPostPhys.17.3.084; arXiv:2401.13029.
  10. [10]B. Czech and X. Dong, Holographic Entropy Cone with Time Dependence in Two Dimensions, JHEP 10 (2019), 177, https://doi.org/10.1007/JHEP10(2019)177; arXiv:1905.03787.
  11. [11]C. Akers, S. Hernández-Cuenca, and P. Rath, Quantum Extremal Surfaces and the Holographic Entropy Cone, JHEP 11 (2021), 177, https://doi.org/10.1007/JHEP11(2021)177; arXiv:2108.07280.
  12. [12]N. Li, C.-S. Dong, D.-H. Du, and F.-W. Shu, Improved proof-by-contraction method and relative homologous entropy inequalities, JHEP 06 (2022), 153, https://doi.org/10.1007/JHEP06(2022)153; arXiv:2204.03192.
  13. [13]N. Bao and J. Naskar, Properties of the contraction map for holographic entanglement entropy inequalities, JHEP 06 (2024), 039, https://doi.org/10.1007/JHEP06(2024)039; arXiv:2403.13283.
  14. [14]N. Bao, K. Furuya, and J. Naskar, Towards a complete classification of holographic entropy inequalities, JHEP 03 (2025), 117, https://doi.org/10.1007/JHEP03(2025)117; arXiv:2409.17317.
  15. [15]B. Czech and S. Shuai, Nesting is not contracting, JHEP 06 (2025), 122, https://doi.org/10.1007/JHEP06(2025)122; arXiv:2501.17222.
  16. [16]G. Grimaldi, M. Headrick, V. E. Hubeny, and P. Shteyner, Combinatorial properties of holographic entropy inequalities, preprint (2026), arXiv:2601.09987.arxiv.org/abs/2601.09987
  17. [17]X.-X. Ju and Y. Zhao, The holographic multi-entropy cone, JHEP 09 (2026), 253, https://doi.org/10.1007/JHEP09(2026)253; arXiv:2606.15173.
  18. [18]N. Bao, N. Cheng, S. Hernández-Cuenca, and V. P. Su, The Quantum Entropy Cone of Hypergraphs, SciPost Phys. 9 (2020), no. 5, 067, https://doi.org/10.21468/SciPostPhys.9.5.067; arXiv:2002.05317.
  19. [19]D. Avis and S. Hernández-Cuenca, On the foundations and extremal structure of the holographic entropy cone, Discrete Appl. Math. 328 (2023), 16–39, https://doi.org/10.1016/j.dam.2022.11.016; arXiv:2102.07535.
  20. [20]N. Bao, K. Furuya, and J. Naskar, On the completeness of contraction map proof method for holographic entropy inequalities, JHEP 12 (2025), 140, https://doi.org/10.1007/JHEP12(2025)140; arXiv:2506.18086v3.
  21. [21]J. Naskar, Multipartite correlations in holography, Ph.D. thesis, Northeastern U., 2026.DOI
  22. [22]B. Czech and S. Shuai, Renormalization group is the principle behind the holographic entropy cone, JHEP 07 (2026), 165, https://doi.org/10.1007/JHEP07(2026)165; arXiv:2601.02472.
  23. [23]B. Czech, Y. Feng, X. Wu, and M. Xie, Holographic entropy inequalities pass the majorization test, SciPost Phys. 21 (2026), no. 2, 048, https://doi.org/10.21468/scipostphys.21.2.048; arXiv:2601.09989.
  24. [24]V. E. Hubeny, M. Rangamani, and M. Rota, The holographic entropy arrangement, Fortsch. Phys. 67 (2019), no. 4, 1900011, https://doi.org/10.1002/prop.201900011; arXiv:1812.08133.
  25. [25]T. He, V. E. Hubeny, and M. Rangamani, Superbalance of Holographic Entropy Inequalities, JHEP 07 (2020), 245, https://doi.org/10.1007/JHEP07(2020)245; arXiv:2002.04558.
  26. [26]N. Alon and V. H. Vũ, Anti-Hadamard Matrices, Coin Weighing, Threshold Gates, and Indecomposable Hypergraphs, J. Combin. Theory Ser. A 79 (1997), no. 1, 133–160, https://doi.org/10.1006/jcta.1997.2780.
  27. [27]N. Wetzler, M. J. H. Heule, and W. A. Hunt, DRAT-trim: Efficient checking and trimming using expressive clausal proofs, in: Theory and Applications of Satisfiability Testing – SAT 2014, Lecture Notes in Computer Science, vol. 8561, Springer International Publishing, 2014, pp. 422–429, https://doi.org/10.1007/978-3-319-09284-3_31.
  28. [28]D. N. Kozlov and V. H. Vu, Coins and Cones, J. Combin. Theory Ser. A 78 (1997), no. 1, 1–14, https://doi.org/10.1006/jcta.1996.2724.
  29. [29]S. X. Cui, P. Hayden, T. He, M. Headrick, B. Stoica, and M. Walter, Bit Threads and Holographic Monogamy, Commun. Math. Phys. 376 (2019), no. 1, 609–648, https://doi.org/10.1007/s00220-019-03510-8; arXiv:1808.05234.
  30. [30]B. Czech and Y. Wang, A holographic inequality for N = 7 regions, JHEP 01 (2023), 101, https://doi.org/10.1007/JHEP01(2023)101; arXiv:2209.10547.
  31. [31]H. Araki and E. H. Lieb, Entropy inequalities, Commun. Math. Phys. 18 (1970), 160–170, https://doi.org/10.1007/BF01646092.
  32. [32]O. Bailleux and Y. Boufkhad, Efficient CNF Encoding of Boolean Cardinality Constraints, in: Principles and Practice of Constraint Programming – CP 2003, Lecture Notes in Computer Science, vol. 2833, Springer Berlin Heidelberg, 2003, pp. 108–122, https://doi.org/10.1007/978-3-540-45193-8_8.
  33. [33]C. Sinz, Towards an Optimal CNF Encoding of Boolean Cardinality Constraints, in: Principles and Practice of Constraint Programming – CP 2005, Lecture Notes in Computer Science, vol. 3709, Springer Berlin Heidelberg, 2005, pp. 827–831, https://doi.org/10.1007/11564751_73.
  34. [34]R. Asín, R. Nieuwenhuis, A. Oliveras, and E. Rodríguez-Carbonell, Cardinality Networks and Their Applications, in: Theory and Applications of Satisfiability Testing – SAT 2009, Lecture Notes in Computer Science, vol. 5584, Springer Berlin Heidelberg, 2009, pp. 167–180, https://doi.org/10.1007/978-3-642-02777-2_18.
  35. [35]A. Ignatiev, A. Morgado, and J. Marques-Silva, PySAT: A Python toolkit for prototyping with SAT oracles, in: Theory and Applications of Satisfiability Testing – SAT 2018, Lecture Notes in Computer Science, vol. 10929, Springer International Publishing, 2018, pp. 428–437, https://doi.org/10.1007/978-3-319-94144-8_26.
  36. [36]A. Biere, T. Faller, K. Fazekas, M. Fleury, N. Froleyks, and F. Pollitt, CaDiCaL 2.0, in: Computer Aided Verification, Lecture Notes in Computer Science, vol. 14681, Springer Nature Switzerland, 2024, pp. 133–152, https://doi.org/10.1007/978-3-031-65627-9_7.
  37. [37]A. Biere, K. Fazekas, M. Fleury, and M. Heisinger, CaDiCaL, Kissat, Paracooba, Plingeling and Treengeling entering the SAT competition 2020, in: Proceedings of SAT Competition 2020: Solver and Benchmark Descriptions (Helsinki) (T. Baylo, N. Froleyks, M. J. H. Heule, M. Iser, M. Järvisalo, and M. Suda, eds.), Department of Computer Science Report Series B, vol. B-2020-1, Department of Computer Science, University of Helsinki, 2020, pp. 50–53, https://researchportal.helsinki.fi/en/publications/proceedings-of-sat-competition-2020-solver-and-benchmark-descript/.
  38. [38]P. Virtanen et al., SciPy 1.0–Fundamental Algorithms for Scientific Computing in Python, Nature Meth. 17 (2020), 261, https://doi.org/10.1038/s41592-019-0686-2; arXiv:1907.10121.
  39. [39]W. H. Cunningham, On submodular function minimization, Combinatorica 5 (1985), no. 3, 185–192, https://doi.org/10.1007/BF02579361.
  40. [40]N. Bao, K. Furuya, and J. Naskar, A framework for generalizing toric inequalities for holographic entanglement entropy, JHEP 10 (2024), 251, https://doi.org/10.1007/JHEP10(2024)251; arXiv:2408.04741.
  41. [41]S. Hernández-Cuenca, V. E. Hubeny, and H. F. Jia, Holographic entropy inequalities and multipartite entanglement, JHEP 08 (2024), 238, https://doi.org/10.1007/JHEP08(2024)238; arXiv:2309.06296.
  42. [42]B. Czech and S. Shuai, Holographic Cone of Average Entropies, Commun. Phys. 5 (2022), 244, https://doi.org/10.1038/s42005-022-01019-6; arXiv:2112.00763.
  43. [43]M. Fadel and S. Hernández-Cuenca, Symmetrized holographic entropy cone, Phys. Rev. D 105 (2022), no. 8, 086008, https://doi.org/10.1103/PhysRevD.105.086008; arXiv:2112.03862.
  44. [44]C.-J. Chou, H. B. Lao, and Y. Yang, A graphical framework for proving holographic entanglement entropy inequalities in multipartite systems, preprint (2025), arXiv:2512.18726.arxiv.org/abs/2512.18726
  45. [45]V. E. Hubeny and Y. Liu, Tripartite Form Universality in Holographic Entropy Inequalities, preprint (2026), arXiv:2609.22504.arxiv.org/abs/2609.22504

Paper details

vlnc:W_hq83jhcr
v1 · latestHistory (1)

published · Fresh — published within the last 30 days

Usage

views · 0

downloads · 0

A view counts once per browser per day, a download each time the PDF is requested.

CC BY 4.0

Original source

  • Physics and Astronomy

Anthropic Claude Opus 5.5 · View statement →

Looking for related papers…
Contents