Pub Date : 2025-12-01DOI: 10.1016/j.aim.2025.110689
Fabrizio Bianchi , Tien-Cuong Dinh
We consider the unique measure of maximal entropy of an automorphism of a compact Kähler manifold with simple action on cohomology. We show that it is exponentially mixing of all orders with respect to Hölder observables. It follows that the Central Limit Theorem (CLT) holds for these observables. In particular, our result applies to all automorphisms of compact Kähler surfaces with positive entropy.
{"title":"Exponential mixing of all orders and CLT for automorphisms of compact Kähler manifolds","authors":"Fabrizio Bianchi , Tien-Cuong Dinh","doi":"10.1016/j.aim.2025.110689","DOIUrl":"10.1016/j.aim.2025.110689","url":null,"abstract":"<div><div>We consider the unique measure of maximal entropy of an automorphism of a compact Kähler manifold with simple action on cohomology. We show that it is exponentially mixing of all orders with respect to Hölder observables. It follows that the Central Limit Theorem (CLT) holds for these observables. In particular, our result applies to all automorphisms of compact Kähler surfaces with positive entropy.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"485 ","pages":"Article 110689"},"PeriodicalIF":1.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694481","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 : 2025-12-01DOI: 10.1016/j.aim.2025.110716
Valentin Blomer, Wing Hong Leung
We give a new proof of the converse theorem for Maaß forms on using a technique that is inspired by Langlands' philosophy of “beyond endoscopy”, thereby implementing these ideas for the first time in a higher rank setting.
{"title":"A GL(3) converse theorem via a “beyond endoscopy” approach","authors":"Valentin Blomer, Wing Hong Leung","doi":"10.1016/j.aim.2025.110716","DOIUrl":"10.1016/j.aim.2025.110716","url":null,"abstract":"<div><div>We give a new proof of the converse theorem for Maaß forms on <span><math><mrow><mi>GL</mi></mrow><mo>(</mo><mn>3</mn><mo>)</mo></math></span> using a technique that is inspired by Langlands' philosophy of “beyond endoscopy”, thereby implementing these ideas for the first time in a higher rank setting.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"485 ","pages":"Article 110716"},"PeriodicalIF":1.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694483","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 : 2025-11-27DOI: 10.1016/j.aim.2025.110714
Lorenzo Notaro
In 1984, Ditor asked two questions:
(A)
For each and infinite cardinal κ, is there a join-semilattice of breadth and cardinality whose principal ideals have cardinality <κ?
(B)
For each , is there a lower finite lattice of cardinality whose elements have at most lower covers?
We show that both questions have positive answers under the axiom of constructibility, and hence consistently with . More specifically, we derive the positive answers from assuming that holds for enough κ's.
{"title":"Ladders and squares","authors":"Lorenzo Notaro","doi":"10.1016/j.aim.2025.110714","DOIUrl":"10.1016/j.aim.2025.110714","url":null,"abstract":"<div><div>In 1984, Ditor asked two questions:<ul><li><span>(A)</span><span><div>For each <span><math><mi>n</mi><mo>∈</mo><mi>ω</mi></math></span> and infinite cardinal <em>κ</em>, is there a join-semilattice of breadth <span><math><mi>n</mi><mo>+</mo><mn>1</mn></math></span> and cardinality <span><math><msup><mrow><mi>κ</mi></mrow><mrow><mo>+</mo><mi>n</mi></mrow></msup></math></span> whose principal ideals have cardinality <<em>κ</em>?</div></span></li><li><span>(B)</span><span><div>For each <span><math><mi>n</mi><mo>∈</mo><mi>ω</mi></math></span>, is there a lower finite lattice of cardinality <span><math><msub><mrow><mi>ℵ</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> whose elements have at most <span><math><mi>n</mi><mo>+</mo><mn>1</mn></math></span> lower covers?</div></span></li></ul> We show that both questions have positive answers under the axiom of constructibility, and hence consistently with <span><math><mi>ZFC</mi></math></span>. More specifically, we derive the positive answers from assuming that <span><math><msub><mrow><mo>□</mo></mrow><mrow><mi>κ</mi></mrow></msub></math></span> holds for enough <em>κ</em>'s.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"485 ","pages":"Article 110714"},"PeriodicalIF":1.5,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600402","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 : 2025-11-27DOI: 10.1016/j.aim.2025.110708
Eilind Karlsson, Corina Keller, Lukas Müller, Ján Pulmann
This paper develops an approach to categorical deformation quantization via factorization homology. We show that a quantization of the local coefficients for factorization homology is equivalent to consistent quantizations of its value on manifolds. To formulate our results we introduce the concepts of shifted almost Poisson and categories.
Our main example is the character stack of flat principal bundles for a reductive algebraic group G, where we show that applying the general framework to the Drinfeld category reproduces deformations previously introduced by Li-Bland and Ševera. As a direct consequence, we can conclude a precise relation between their quantization and those introduced by Alekseev, Grosse, and Schomerus.
To arrive at our results we compute factorization homology with values in a ribbon category enriched over complete -modules. More generally, we define enriched skein categories which compute factorization homology for ribbon categories enriched over a general closed symmetric monoidal category .
{"title":"Deformation quantization via categorical factorization homology","authors":"Eilind Karlsson, Corina Keller, Lukas Müller, Ján Pulmann","doi":"10.1016/j.aim.2025.110708","DOIUrl":"10.1016/j.aim.2025.110708","url":null,"abstract":"<div><div>This paper develops an approach to categorical deformation quantization via factorization homology. We show that a quantization of the local coefficients for factorization homology is equivalent to consistent quantizations of its value on manifolds. To formulate our results we introduce the concepts of shifted almost Poisson and <span><math><mi>BD</mi></math></span> categories.</div><div>Our main example is the character stack of flat principal bundles for a reductive algebraic group <em>G</em>, where we show that applying the general framework to the Drinfeld category reproduces deformations previously introduced by Li-Bland and Ševera. As a direct consequence, we can conclude a precise relation between their quantization and those introduced by Alekseev, Grosse, and Schomerus.</div><div>To arrive at our results we compute factorization homology with values in a ribbon category enriched over complete <span><math><mi>C</mi><mo>[</mo><mo>[</mo><mi>ħ</mi><mo>]</mo><mo>]</mo></math></span>-modules. More generally, we define enriched skein categories which compute factorization homology for ribbon categories enriched over a general closed symmetric monoidal category <span><math><mi>V</mi></math></span>.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"484 ","pages":"Article 110708"},"PeriodicalIF":1.5,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625099","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 : 2025-11-27DOI: 10.1016/j.aim.2025.110711
Masaki Kashiwara , Myungho Kim
Admissible chains of i-boxes are important combinatorial tools in the monoidal categorification of cluster algebras, as they provide seeds of the cluster algebra. In this paper, we explore the properties of maximal commuting families of i-boxes in a more general setting, and define a certain matrix associated with such a family, which we call the exchange matrix. It turns out that, when considering the cluster algebra structure on the Grothendieck rings, this matrix is indeed the exchange matrix of the seed associated with the family, both in certain categories of modules over quantum affine algebras and over quiver Hecke algebras. We prove this by constructing explicit short exact sequences that represent the mutation relations.
{"title":"Exchange matrices of I-boxes","authors":"Masaki Kashiwara , Myungho Kim","doi":"10.1016/j.aim.2025.110711","DOIUrl":"10.1016/j.aim.2025.110711","url":null,"abstract":"<div><div>Admissible chains of <strong>i</strong>-boxes are important combinatorial tools in the monoidal categorification of cluster algebras, as they provide seeds of the cluster algebra. In this paper, we explore the properties of maximal commuting families of <strong>i</strong>-boxes in a more general setting, and define a certain matrix associated with such a family, which we call the exchange matrix. It turns out that, when considering the cluster algebra structure on the Grothendieck rings, this matrix is indeed the exchange matrix of the seed associated with the family, both in certain categories of modules over quantum affine algebras and over quiver Hecke algebras. We prove this by constructing explicit short exact sequences that represent the mutation relations.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"485 ","pages":"Article 110711"},"PeriodicalIF":1.5,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625308","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 : 2025-11-26DOI: 10.1016/j.aim.2025.110710
Derong Kong , Beibei Sun , Zhiqiang Wang
<div><div>Given an integer <span><math><mi>b</mi><mo>≥</mo><mn>3</mn></math></span>, let <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>:</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>→</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>;</mo><mi>x</mi><mo>↦</mo><mi>b</mi><mi>x</mi><mspace></mspace><mo>(</mo><mrow><mi>mod</mi></mrow><mspace></mspace><mn>1</mn><mo>)</mo></math></span> be the expanding map on the unit circle. For any <span><math><mi>m</mi><mo>∈</mo><mi>N</mi></math></span> and for any <span><math><mi>ω</mi><mo>=</mo><msup><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msup><mo>…</mo><mo>∈</mo><msup><mrow><mo>(</mo><msup><mrow><mo>{</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>b</mi><mo>−</mo><mn>1</mn><mo>}</mo></mrow><mrow><mi>m</mi></mrow></msup><mo>)</mo></mrow><mrow><msub><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></msup></math></span> let<span><span><span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup><mo>=</mo><mrow><mo>{</mo><mi>x</mi><mo>∈</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>:</mo><msubsup><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow><mrow><mi>n</mi></mrow></msubsup><mo>(</mo><mi>x</mi><mo>)</mo><mo>∉</mo><msub><mrow><mi>I</mi></mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msub><mspace></mspace><mo>∀</mo><mi>n</mi><mo>≥</mo><mn>0</mn><mo>}</mo></mrow><mo>,</mo></math></span></span></span> where <span><math><msub><mrow><mi>I</mi></mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msub></math></span> is the <em>b</em>-adic basic interval generated by <span><math><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></math></span>. Then <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span> is called the survivor set of the open dynamical system <span><math><mo>(</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>,</mo><msub><mrow><mi>I</mi></mrow><mrow><mi>ω</mi></mrow></msub><mo>)</mo></math></span> with respect to the sequence of holes <span><math><msub><mrow><mi>I</mi></mrow><mrow><mi>ω</mi></mrow></msub><mo>=</mo><mrow><mo>{</mo><msub><mrow><mi>I</mi></mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msub><mo>:</mo><mi>n</mi><mo>≥</mo><mn>0</mn><mo>}</mo></mrow></math></span>. We show that the Hausdorff and lower box dimensions of <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span> always coincide, and the packing and upper box dimensions of <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span> also coincide. Moreover, we give sharp lower and upper bounds for the dimensions of <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span>, which can
{"title":"Open dynamical systems with a moving hole","authors":"Derong Kong , Beibei Sun , Zhiqiang Wang","doi":"10.1016/j.aim.2025.110710","DOIUrl":"10.1016/j.aim.2025.110710","url":null,"abstract":"<div><div>Given an integer <span><math><mi>b</mi><mo>≥</mo><mn>3</mn></math></span>, let <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>:</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>→</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>;</mo><mi>x</mi><mo>↦</mo><mi>b</mi><mi>x</mi><mspace></mspace><mo>(</mo><mrow><mi>mod</mi></mrow><mspace></mspace><mn>1</mn><mo>)</mo></math></span> be the expanding map on the unit circle. For any <span><math><mi>m</mi><mo>∈</mo><mi>N</mi></math></span> and for any <span><math><mi>ω</mi><mo>=</mo><msup><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msup><mo>…</mo><mo>∈</mo><msup><mrow><mo>(</mo><msup><mrow><mo>{</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>b</mi><mo>−</mo><mn>1</mn><mo>}</mo></mrow><mrow><mi>m</mi></mrow></msup><mo>)</mo></mrow><mrow><msub><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></msup></math></span> let<span><span><span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup><mo>=</mo><mrow><mo>{</mo><mi>x</mi><mo>∈</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>:</mo><msubsup><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow><mrow><mi>n</mi></mrow></msubsup><mo>(</mo><mi>x</mi><mo>)</mo><mo>∉</mo><msub><mrow><mi>I</mi></mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msub><mspace></mspace><mo>∀</mo><mi>n</mi><mo>≥</mo><mn>0</mn><mo>}</mo></mrow><mo>,</mo></math></span></span></span> where <span><math><msub><mrow><mi>I</mi></mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msub></math></span> is the <em>b</em>-adic basic interval generated by <span><math><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></math></span>. Then <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span> is called the survivor set of the open dynamical system <span><math><mo>(</mo><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>,</mo><msub><mrow><mi>I</mi></mrow><mrow><mi>ω</mi></mrow></msub><mo>)</mo></math></span> with respect to the sequence of holes <span><math><msub><mrow><mi>I</mi></mrow><mrow><mi>ω</mi></mrow></msub><mo>=</mo><mrow><mo>{</mo><msub><mrow><mi>I</mi></mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msub><mo>:</mo><mi>n</mi><mo>≥</mo><mn>0</mn><mo>}</mo></mrow></math></span>. We show that the Hausdorff and lower box dimensions of <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span> always coincide, and the packing and upper box dimensions of <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span> also coincide. Moreover, we give sharp lower and upper bounds for the dimensions of <span><math><msup><mrow><mi>K</mi></mrow><mrow><mi>ω</mi></mrow></msup></math></span>, which can","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"484 ","pages":"Article 110710"},"PeriodicalIF":1.5,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625105","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 : 2025-11-26DOI: 10.1016/j.aim.2025.110697
Ziqiang Feng
We consider the class of partially hyperbolic diffeomorphisms on a closed 3-manifold with quasi-isometric center. When the non-wandering set is the whole manifold, we prove that the diffeomorphisms are accessible if there is no su-torus. As a consequence, volume-preserving diffeomorphisms in this context are ergodic in the absence of su-tori, thereby confirming the Hertz-Hertz-Ures Ergodicity Conjecture for this class.
For any closed 3-manifold with fundamental group of exponential growth, we show that it supports transitive Anosov flows if and only if it admits non-wandering partially hyperbolic diffeomorphisms with quasi-isometric center. Furthermore, we provide a complete classification of these diffeomorphisms, showing they fall into two categories: skew products and discretized Anosov flows.
{"title":"Partially hyperbolic dynamics with quasi-isometric center","authors":"Ziqiang Feng","doi":"10.1016/j.aim.2025.110697","DOIUrl":"10.1016/j.aim.2025.110697","url":null,"abstract":"<div><div>We consider the class of partially hyperbolic diffeomorphisms on a closed 3-manifold with quasi-isometric center. When the non-wandering set is the whole manifold, we prove that the diffeomorphisms are accessible if there is no <em>su</em>-torus. As a consequence, volume-preserving diffeomorphisms in this context are ergodic in the absence of <em>su</em>-tori, thereby confirming the Hertz-Hertz-Ures Ergodicity Conjecture for this class.</div><div>For any closed 3-manifold with fundamental group of exponential growth, we show that it supports transitive Anosov flows if and only if it admits non-wandering partially hyperbolic diffeomorphisms with quasi-isometric center. Furthermore, we provide a complete classification of these diffeomorphisms, showing they fall into two categories: skew products and discretized Anosov flows.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"484 ","pages":"Article 110697"},"PeriodicalIF":1.5,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625100","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 : 2025-11-26DOI: 10.1016/j.aim.2025.110680
Chris Connell , Yuping Ruan , Shi Wang
We show that for any closed nonpositively curved Riemannian 4-manifold M with vanishing Euler characteristic, the Ricci curvature must degenerate somewhere. Moreover, for each point , either the Ricci tensor degenerates or else there is a foliation by totally geodesic flat 3-manifolds in a neighborhood of p. As a corollary, we show that if in addition the metric is analytic, then the universal cover of M has a nontrivial Euclidean de Rham factor. Finally we discuss how this result creates an implication among conjectures on simplicial volume in dimension four.
{"title":"Nonpositively curved 4-manifolds with zero Euler characteristic","authors":"Chris Connell , Yuping Ruan , Shi Wang","doi":"10.1016/j.aim.2025.110680","DOIUrl":"10.1016/j.aim.2025.110680","url":null,"abstract":"<div><div>We show that for any closed nonpositively curved Riemannian 4-manifold <em>M</em> with vanishing Euler characteristic, the Ricci curvature must degenerate somewhere. Moreover, for each point <span><math><mi>p</mi><mo>∈</mo><mi>M</mi></math></span>, either the Ricci tensor degenerates or else there is a foliation by totally geodesic flat 3-manifolds in a neighborhood of <em>p</em>. As a corollary, we show that if in addition the metric is analytic, then the universal cover of <em>M</em> has a nontrivial Euclidean de Rham factor. Finally we discuss how this result creates an implication among conjectures on simplicial volume in dimension four.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"484 ","pages":"Article 110680"},"PeriodicalIF":1.5,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625101","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 : 2025-11-26DOI: 10.1016/j.aim.2025.110713
P. Gohlke , A. Mitchell , D. Rust , T. Samuel
We develop a theory of Rauzy fractals for random substitutions, which are a generalisation of deterministic substitutions where the substituted image of a letter is determined by a Markov process. We show that a Rauzy fractal can be associated with a given random substitution in a canonical manner, under natural assumptions on the random substitution. Further, we show the existence of a natural measure supported on the Rauzy fractal, which we call the Rauzy measure, that captures geometric and dynamical information. We provide several different constructions for the Rauzy fractal and Rauzy measure, which we show coincide, and ascertain various analytic, dynamical and geometric properties. While the Rauzy fractal is independent of the choice of (non-degenerate) probabilities assigned to a given random substitution, the Rauzy measure captures the explicit choice of probabilities. Moreover, Rauzy measures vary continuously with the choice of probabilities, thus provide a natural means of interpolating between Rauzy fractals of deterministic substitutions. Additionally, we highlight connections between Rauzy fractals and Rauzy measures of random substitutions and related S-adic systems.
{"title":"Rauzy fractals of random substitutions","authors":"P. Gohlke , A. Mitchell , D. Rust , T. Samuel","doi":"10.1016/j.aim.2025.110713","DOIUrl":"10.1016/j.aim.2025.110713","url":null,"abstract":"<div><div>We develop a theory of Rauzy fractals for random substitutions, which are a generalisation of deterministic substitutions where the substituted image of a letter is determined by a Markov process. We show that a Rauzy fractal can be associated with a given random substitution in a canonical manner, under natural assumptions on the random substitution. Further, we show the existence of a natural measure supported on the Rauzy fractal, which we call the Rauzy measure, that captures geometric and dynamical information. We provide several different constructions for the Rauzy fractal and Rauzy measure, which we show coincide, and ascertain various analytic, dynamical and geometric properties. While the Rauzy fractal is independent of the choice of (non-degenerate) probabilities assigned to a given random substitution, the Rauzy measure captures the explicit choice of probabilities. Moreover, Rauzy measures vary continuously with the choice of probabilities, thus provide a natural means of interpolating between Rauzy fractals of deterministic substitutions. Additionally, we highlight connections between Rauzy fractals and Rauzy measures of random substitutions and related S-adic systems.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"485 ","pages":"Article 110713"},"PeriodicalIF":1.5,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600403","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 : 2025-11-26DOI: 10.1016/j.aim.2025.110707
Amlan Banaji , Jonathan M. Fraser , István Kolossváry , Alex Rutar
We study the fine local scaling properties of a class of self-affine fractal sets called Gatzouras–Lalley carpets. More precisely, we establish a formula for the Assouad spectrum of all Gatzouras–Lalley carpets as the concave conjugate of an explicit piecewise-analytic function combined with a simple parameter change. Our formula implies a number of novel properties for the Assouad spectrum not previously observed for dynamically invariant sets; in particular, the Assouad spectrum can be a non-trivial differentiable function on the entire domain and can be strictly concave on open intervals. Our proof introduces a general framework for covering arguments using techniques developed in the context of multifractal analysis, including the method of types from large deviations theory and Lagrange duality from optimisation theory.
{"title":"Assouad spectrum of Gatzouras–Lalley carpets","authors":"Amlan Banaji , Jonathan M. Fraser , István Kolossváry , Alex Rutar","doi":"10.1016/j.aim.2025.110707","DOIUrl":"10.1016/j.aim.2025.110707","url":null,"abstract":"<div><div>We study the fine local scaling properties of a class of self-affine fractal sets called Gatzouras–Lalley carpets. More precisely, we establish a formula for the Assouad spectrum of all Gatzouras–Lalley carpets as the concave conjugate of an explicit piecewise-analytic function combined with a simple parameter change. Our formula implies a number of novel properties for the Assouad spectrum not previously observed for dynamically invariant sets; in particular, the Assouad spectrum can be a non-trivial differentiable function on the entire domain <span><math><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></math></span> and can be strictly concave on open intervals. Our proof introduces a general framework for covering arguments using techniques developed in the context of multifractal analysis, including the method of types from large deviations theory and Lagrange duality from optimisation theory.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"484 ","pages":"Article 110707"},"PeriodicalIF":1.5,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145624700","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}