Pub Date : 2025-02-18DOI: 10.1016/j.aim.2025.110154
Guoce Xin , Chen Zhang , Yue Zhou , Yueming Zhong
In this paper, we discover a new noncommutative algebra. We refer this algebra as the constant term algebra of type A, which is generated by certain constant term operators. We characterize a structural result of this algebra by establishing an explicit basis in terms of certain forests. This algebra arises when we apply the method of the iterated Laurent series to investigate Beck and Pixton's residue computation for the Ehrhart series of the Birkhoff polytope. This algebra seems to be the first structural result in the area of the constant term world since the discovery of the Dyson constant term identity in 1962.
{"title":"The constant term algebra of type A: The structure","authors":"Guoce Xin , Chen Zhang , Yue Zhou , Yueming Zhong","doi":"10.1016/j.aim.2025.110154","DOIUrl":"10.1016/j.aim.2025.110154","url":null,"abstract":"<div><div>In this paper, we discover a new noncommutative algebra. We refer this algebra as the constant term algebra of type <em>A</em>, which is generated by certain constant term operators. We characterize a structural result of this algebra by establishing an explicit basis in terms of certain forests. This algebra arises when we apply the method of the iterated Laurent series to investigate Beck and Pixton's residue computation for the Ehrhart series of the Birkhoff polytope. This algebra seems to be the first structural result in the area of the constant term world since the discovery of the Dyson constant term identity in 1962.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110154"},"PeriodicalIF":1.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.aim.2025.110134
Nobuo Iida , Anubhav Mukherjee , Masaki Taniguchi
Our main result gives an adjunction inequality for embedded surfaces in certain 4-manifolds with contact boundary under a non-vanishing assumption on the Bauer–Furuta type invariants. Using this, we give infinitely many knots in that are not smoothly H-slice (that is, bounding a null-homologous disk) in many 4-manifolds but they are topologically H-slice. In particular, we give such knots in the boundaries of the punctured elliptic surfaces . In addition, we give obstructions to codimension-0 orientation-reversing embedding of weak symplectic fillings with into closed symplectic 4-manifolds with and . From here we prove a Bennequin type inequality for strong symplectic caps of . We also show that any weakly symplectically fillable 3-manifold bounds a 4-manifold with at least two smooth structures.
{"title":"An adjunction inequality for the Bauer–Furuta type invariants, with applications to sliceness and 4-manifold topology","authors":"Nobuo Iida , Anubhav Mukherjee , Masaki Taniguchi","doi":"10.1016/j.aim.2025.110134","DOIUrl":"10.1016/j.aim.2025.110134","url":null,"abstract":"<div><div>Our main result gives an adjunction inequality for embedded surfaces in certain 4-manifolds with contact boundary under a non-vanishing assumption on the Bauer–Furuta type invariants. Using this, we give infinitely many knots in <span><math><msup><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msup></math></span> that are not smoothly H-slice (that is, bounding a null-homologous disk) in many 4-manifolds but they are topologically H-slice. In particular, we give such knots in the boundaries of the punctured elliptic surfaces <span><math><mi>E</mi><mo>(</mo><mn>2</mn><mi>n</mi><mo>)</mo></math></span>. In addition, we give obstructions to codimension-0 orientation-reversing embedding of weak symplectic fillings with <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>0</mn></math></span> into closed symplectic 4-manifolds with <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mn>0</mn></math></span> and <span><math><msubsup><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>≡</mo><mn>3</mn><mi>mod</mi><mspace></mspace><mn>4</mn></math></span>. From here we prove a Bennequin type inequality for strong symplectic caps of <span><math><mo>(</mo><msup><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>,</mo><msub><mrow><mi>ξ</mi></mrow><mrow><mi>s</mi><mi>t</mi><mi>d</mi></mrow></msub><mo>)</mo></math></span>. We also show that any weakly symplectically fillable 3-manifold bounds a 4-manifold with at least two smooth structures.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"466 ","pages":"Article 110134"},"PeriodicalIF":1.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.aim.2025.110159
Peng Sun
For a dynamical system satisfying the approximate product property and asymptotically entropy expansiveness, we characterize a delicate structure of the space of invariant measures: The ergodic measures of intermediate entropies and the ones of intermediate pressures are generic in certain subspaces. Consequently, the conjecture of Katok that ergodic measures of arbitrary intermediate entropy exist is verified for a broad class of systems.
{"title":"Ergodic measures of intermediate entropies for dynamical systems with the approximate product property","authors":"Peng Sun","doi":"10.1016/j.aim.2025.110159","DOIUrl":"10.1016/j.aim.2025.110159","url":null,"abstract":"<div><div>For a dynamical system satisfying the approximate product property and asymptotically entropy expansiveness, we characterize a delicate structure of the space of invariant measures: The ergodic measures of intermediate entropies and the ones of intermediate pressures are generic in certain subspaces. Consequently, the conjecture of Katok that ergodic measures of arbitrary intermediate entropy exist is verified for a broad class of systems.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110159"},"PeriodicalIF":1.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.aim.2025.110155
Vladimir Mikhailets , Aleksandr Murach , Tetiana Zinchenko
We propose a new viewpoint on Hilbert scales extending them by means of all Hilbert spaces that are interpolation ones between spaces on the scale. We prove that this extension admits an explicit description with the help of OR-varying functions of the operator generating the scale. We also show that this extended Hilbert scale is obtained by the quadratic interpolation (with function parameter) between the above spaces and is closed with respect to the quadratic interpolation between Hilbert spaces. We give applications of the extended Hilbert scale to interpolational inequalities, generalized Sobolev spaces, and spectral expansions induced by abstract and elliptic operators; this specifically allows obtaining new results for multiple Fourier series.
{"title":"An extended Hilbert scale and its applications","authors":"Vladimir Mikhailets , Aleksandr Murach , Tetiana Zinchenko","doi":"10.1016/j.aim.2025.110155","DOIUrl":"10.1016/j.aim.2025.110155","url":null,"abstract":"<div><div>We propose a new viewpoint on Hilbert scales extending them by means of all Hilbert spaces that are interpolation ones between spaces on the scale. We prove that this extension admits an explicit description with the help of OR-varying functions of the operator generating the scale. We also show that this extended Hilbert scale is obtained by the quadratic interpolation (with function parameter) between the above spaces and is closed with respect to the quadratic interpolation between Hilbert spaces. We give applications of the extended Hilbert scale to interpolational inequalities, generalized Sobolev spaces, and spectral expansions induced by abstract and elliptic operators; this specifically allows obtaining new results for multiple Fourier series.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110155"},"PeriodicalIF":1.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.aim.2025.110157
Bassam Fayad, Adam Kanigowski, Rigoberto Zelada
We construct a smooth area preserving flow on a genus 2 surface with exactly one open uniquely ergodic component, that is asymmetrically bounded by separatrices of non-degenerate saddles and that is nevertheless not mixing.
{"title":"A non-mixing Arnold flow on a surface","authors":"Bassam Fayad, Adam Kanigowski, Rigoberto Zelada","doi":"10.1016/j.aim.2025.110157","DOIUrl":"10.1016/j.aim.2025.110157","url":null,"abstract":"<div><div>We construct a smooth area preserving flow on a genus 2 surface with exactly one open uniquely ergodic component, that is asymmetrically bounded by separatrices of non-degenerate saddles and that is nevertheless not mixing.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110157"},"PeriodicalIF":1.5,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.aim.2025.110160
Benson Farb
We prove that the intermediate Jacobian of the Klein quartic 3-fold X is not isomorphic, as a principally polarized abelian variety, to a product of Jacobians of curves. As corollaries we deduce (using a criterion of Clemens-Griffiths) that X, as well as the general smooth quartic 3-fold, is irrational. These corollaries were known: Iskovskih-Manin [14] proved that every smooth quartic 3-fold is irrational. However, the method of proof here is different than that of [14], is significantly simpler, and produces an explicit example.
{"title":"Irrationality of the general smooth quartic 3-fold using intermediate Jacobians","authors":"Benson Farb","doi":"10.1016/j.aim.2025.110160","DOIUrl":"10.1016/j.aim.2025.110160","url":null,"abstract":"<div><div>We prove that the intermediate Jacobian of the Klein quartic 3-fold <em>X</em> is not isomorphic, as a principally polarized abelian variety, to a product of Jacobians of curves. As corollaries we deduce (using a criterion of Clemens-Griffiths) that <em>X</em>, as well as the general smooth quartic 3-fold, is irrational. These corollaries were known: Iskovskih-Manin <span><span>[14]</span></span> proved that every smooth quartic 3-fold is irrational. However, the method of proof here is different than that of <span><span>[14]</span></span>, is significantly simpler, and produces an explicit example.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110160"},"PeriodicalIF":1.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.aim.2025.110153
Yuta Takaya
We prove the equidimensionality of affine Deligne-Lusztig varieties in mixed characteristic. This verifies a conjecture made by Rapoport and implies that the results of Nie and Zhou-Zhu can be extended to the whole irreducible components of affine Deligne-Lusztig varieties. The method is to translate the work of Hartl-Viehmann into mixed characteristic and construct local foliations for affine Deligne-Lusztig varieties. This leads us to develop a theory of formal algebraic geometry for perfect schemes.
{"title":"Equidimensionality of affine Deligne-Lusztig varieties in mixed characteristic","authors":"Yuta Takaya","doi":"10.1016/j.aim.2025.110153","DOIUrl":"10.1016/j.aim.2025.110153","url":null,"abstract":"<div><div>We prove the equidimensionality of affine Deligne-Lusztig varieties in mixed characteristic. This verifies a conjecture made by Rapoport and implies that the results of Nie and Zhou-Zhu can be extended to the whole irreducible components of affine Deligne-Lusztig varieties. The method is to translate the work of Hartl-Viehmann into mixed characteristic and construct local foliations for affine Deligne-Lusztig varieties. This leads us to develop a theory of formal algebraic geometry for perfect schemes.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110153"},"PeriodicalIF":1.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.aim.2025.110151
Truong Hoang
A modern insight due to Quillen, which is further developed by Lurie, asserts that many cohomology theories of interest are particular cases of a single construction, which allows one to define cohomology groups in an abstract setting using only intrinsic properties of the category (or ∞-category) at hand. This universal cohomology theory is known as Quillen cohomology. In any setting, Quillen cohomology of a given object is classified by its cotangent complex. The main purpose of this paper is to study Quillen cohomology of operads enriched over a general base category. Our main result provides an explicit formula for computing Quillen cohomology of enriched operads, based on a procedure of taking certain infinitesimal models of their cotangent complexes. Furthermore, we propose a natural construction of the twisted arrow ∞-categories of simplicial operads. We then assert that the cotangent complex of a simplicial operad can be represented as a spectrum valued functor on its twisted arrow ∞-category.
When working in stable base categories such as chain complexes and spectra, Francis and Lurie proved the existence of a fiber sequence relating the cotangent complex and Hochschild complex of an -algebra, from which a conjecture of Kontsevich is verified. We establish an analogous fiber sequence for the operad itself, in the topological setting.
{"title":"Quillen cohomology of enriched operads","authors":"Truong Hoang","doi":"10.1016/j.aim.2025.110151","DOIUrl":"10.1016/j.aim.2025.110151","url":null,"abstract":"<div><div>A modern insight due to Quillen, which is further developed by Lurie, asserts that many cohomology theories of interest are particular cases of a single construction, which allows one to define cohomology groups in an abstract setting using only intrinsic properties of the category (or ∞-category) at hand. This universal cohomology theory is known as Quillen cohomology. In any setting, Quillen cohomology of a given object is classified by its cotangent complex. The main purpose of this paper is to study Quillen cohomology of operads enriched over a general base category. Our main result provides an explicit formula for computing Quillen cohomology of enriched operads, based on a procedure of taking certain infinitesimal models of their cotangent complexes. Furthermore, we propose a natural construction of the twisted arrow ∞-categories of simplicial operads. We then assert that the cotangent complex of a simplicial operad can be represented as a spectrum valued functor on its twisted arrow ∞-category.</div><div>When working in stable base categories such as chain complexes and spectra, Francis and Lurie proved the existence of a fiber sequence relating the cotangent complex and Hochschild complex of an <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span>-algebra, from which a conjecture of Kontsevich is verified. We establish an analogous fiber sequence for the operad <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> itself, in the topological setting.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110151"},"PeriodicalIF":1.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.aim.2025.110146
Cuipo Jiang , Ching Hung Lam , Hiroshi Yamauchi
We classify vertex operator algebras (VOAs) of OZ-type generated by Ising vectors of σ-type. As a consequence of the classification, we also prove that such VOAs are simple, rational, -cofinite and unitary, that is, they have compact real forms generated by Ising vectors of σ-type over the real numbers.
{"title":"The classification of vertex operator algebras of OZ-type generated by Ising vectors of σ-type","authors":"Cuipo Jiang , Ching Hung Lam , Hiroshi Yamauchi","doi":"10.1016/j.aim.2025.110146","DOIUrl":"10.1016/j.aim.2025.110146","url":null,"abstract":"<div><div>We classify vertex operator algebras (VOAs) of OZ-type generated by Ising vectors of <em>σ</em>-type. As a consequence of the classification, we also prove that such VOAs are simple, rational, <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-cofinite and unitary, that is, they have compact real forms generated by Ising vectors of <em>σ</em>-type over the real numbers.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110146"},"PeriodicalIF":1.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.aim.2025.110149
Tsukasa Ishibashi , Wataru Yuasa
As a sequel to our previous work [18] on the -case, we introduce a skein algebra consisting of -webs on a marked surface Σ, incorporating certain “clasped” skein relations at special points. We further investigate its cluster structure. We also define a natural -form , while the natural coefficient ring of includes the inverse of the quantum integer . We prove that its boundary-localization embeds into a quantum cluster algebra that quantizes the function ring of the moduli space . Furthermore, we establish the positivity of Laurent expressions of elevation-preserving webs, following an approach similar to [18]. We also propose a characterization of cluster variables in the spirit of Fomin–Pylyavskyy [9] using -webs, and provide infinitely many supporting examples on a quadrilateral.
{"title":"Skein and cluster algebras of unpunctured surfaces for sp4","authors":"Tsukasa Ishibashi , Wataru Yuasa","doi":"10.1016/j.aim.2025.110149","DOIUrl":"10.1016/j.aim.2025.110149","url":null,"abstract":"<div><div>As a sequel to our previous work <span><span>[18]</span></span> on the <span><math><msub><mrow><mi>sl</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>-case, we introduce a skein algebra <span><math><msubsup><mrow><mi>S</mi></mrow><mrow><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><mi>q</mi></mrow></msubsup></math></span> consisting of <span><math><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span>-webs on a marked surface Σ, incorporating certain “clasped” skein relations at special points. We further investigate its cluster structure. We also define a natural <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>-form <span><math><msubsup><mrow><mi>S</mi></mrow><mrow><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><msub><mrow><mi>Z</mi></mrow><mrow><mi>q</mi></mrow></msub></mrow></msubsup><mo>⊂</mo><msubsup><mrow><mi>S</mi></mrow><mrow><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><mi>q</mi></mrow></msubsup></math></span>, while the natural coefficient ring <span><math><mi>R</mi></math></span> of <span><math><msubsup><mrow><mi>S</mi></mrow><mrow><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><mi>q</mi></mrow></msubsup></math></span> includes the inverse of the quantum integer <span><math><msub><mrow><mo>[</mo><mn>2</mn><mo>]</mo></mrow><mrow><mi>q</mi></mrow></msub></math></span>. We prove that its boundary-localization <span><math><msubsup><mrow><mi>S</mi></mrow><mrow><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><msub><mrow><mi>Z</mi></mrow><mrow><mi>q</mi></mrow></msub></mrow></msubsup><mo>[</mo><msup><mrow><mo>∂</mo></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>]</mo></math></span> embeds into a quantum cluster algebra <span><math><msubsup><mrow><mi>A</mi></mrow><mrow><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><mi>q</mi></mrow></msubsup></math></span> that quantizes the function ring of the moduli space <span><math><msubsup><mrow><mi>A</mi></mrow><mrow><mi>S</mi><msub><mrow><mi>p</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>,</mo><mi>Σ</mi></mrow><mrow><mo>×</mo></mrow></msubsup></math></span>. Furthermore, we establish the positivity of Laurent expressions of elevation-preserving webs, following an approach similar to <span><span>[18]</span></span>. We also propose a characterization of cluster variables in the spirit of Fomin–Pylyavskyy <span><span>[9]</span></span> using <span><math><msub><mrow><mi>sp</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span>-webs, and provide infinitely many supporting examples on a quadrilateral.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"465 ","pages":"Article 110149"},"PeriodicalIF":1.5,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}