Nesting is not contracting

Abstract The default way of proving holographic entropy inequalities is the contraction method. It divides Ryu-Takayanagi (RT) surfaces on the ‘greater than’ side of the inequality into segments, then glues the segments into candidate RT surfaces for terms on the ‘less than’ side. Here we discuss ho...

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Main Authors: Bartłomiej Czech, Sirui Shuai
Format: Article
Language:English
Published: SpringerOpen 2025-06-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP06(2025)122
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author Bartłomiej Czech
Sirui Shuai
author_facet Bartłomiej Czech
Sirui Shuai
author_sort Bartłomiej Czech
collection DOAJ
description Abstract The default way of proving holographic entropy inequalities is the contraction method. It divides Ryu-Takayanagi (RT) surfaces on the ‘greater than’ side of the inequality into segments, then glues the segments into candidate RT surfaces for terms on the ‘less than’ side. Here we discuss how proofs by contraction are constrained and informed by entanglement wedge nesting (EWN)—the property that enlarging a boundary region can only enlarge its entanglement wedge. We propose that: (i) all proofs by contraction necessarily involve candidate RT surfaces, which violate EWN; (ii) violations of EWN in contraction proofs of maximally tight inequalities occur commonly and — where this can be quantified — with maximal density near boundary conditions; (iii) the non-uniqueness of proofs by contraction reflects inequivalent ways of violating EWN. As evidence and illustration, we study the recently discovered infinite families of holographic entropy inequalities, which are associated with tessellations of the torus and the projective plane. We explain the logic, which underlies their proofs by contraction. We find that all salient aspects of the requisite contraction maps are dictated by EWN while all their variable aspects set the scheme for how to violate EWN. We comment on whether the tension between EWN and contraction maps might help in characterizing maximally tight holographic entropy inequalities.
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spelling doaj-art-065c263e99c6465b83f7bea3362cdd312025-08-20T03:42:43ZengSpringerOpenJournal of High Energy Physics1029-84792025-06-012025614510.1007/JHEP06(2025)122Nesting is not contractingBartłomiej Czech0Sirui Shuai1Institute for Advanced Study, Tsinghua UniversityInstitute for Advanced Study, Tsinghua UniversityAbstract The default way of proving holographic entropy inequalities is the contraction method. It divides Ryu-Takayanagi (RT) surfaces on the ‘greater than’ side of the inequality into segments, then glues the segments into candidate RT surfaces for terms on the ‘less than’ side. Here we discuss how proofs by contraction are constrained and informed by entanglement wedge nesting (EWN)—the property that enlarging a boundary region can only enlarge its entanglement wedge. We propose that: (i) all proofs by contraction necessarily involve candidate RT surfaces, which violate EWN; (ii) violations of EWN in contraction proofs of maximally tight inequalities occur commonly and — where this can be quantified — with maximal density near boundary conditions; (iii) the non-uniqueness of proofs by contraction reflects inequivalent ways of violating EWN. As evidence and illustration, we study the recently discovered infinite families of holographic entropy inequalities, which are associated with tessellations of the torus and the projective plane. We explain the logic, which underlies their proofs by contraction. We find that all salient aspects of the requisite contraction maps are dictated by EWN while all their variable aspects set the scheme for how to violate EWN. We comment on whether the tension between EWN and contraction maps might help in characterizing maximally tight holographic entropy inequalities.https://doi.org/10.1007/JHEP06(2025)122AdS-CFT CorrespondenceGauge-Gravity Correspondence
spellingShingle Bartłomiej Czech
Sirui Shuai
Nesting is not contracting
Journal of High Energy Physics
AdS-CFT Correspondence
Gauge-Gravity Correspondence
title Nesting is not contracting
title_full Nesting is not contracting
title_fullStr Nesting is not contracting
title_full_unstemmed Nesting is not contracting
title_short Nesting is not contracting
title_sort nesting is not contracting
topic AdS-CFT Correspondence
Gauge-Gravity Correspondence
url https://doi.org/10.1007/JHEP06(2025)122
work_keys_str_mv AT bartłomiejczech nestingisnotcontracting
AT siruishuai nestingisnotcontracting