Pub Date : 2026-01-08DOI: 10.1016/j.aim.2025.110763
Dražen Adamović , Antun Milas
We construct a family of potentially quasi-lisse (non-rational) vertex algebras, denoted by , , which are closely related to the vertex algebra of chiral differential operators on at level . We prove that for , there is an isomorphism between and the affine vertex algebra from the Cvitanović-Deligne series. Moreover, we also establish isomorphisms between and and certain affine W-algebras of types and , respectively. In this way, we resolve the problem of decomposing certain conformal embeddings of affine vertex algebras into affine W-algebras. An important feature is that is -graded with finite-dimensional graded subspaces and convergent characters. Therefore, for all , we show that the characters of exhibit modularity, supporting the conjectural quasi-lisse property.
{"title":"Vertex algebras related to regular representations of SL2","authors":"Dražen Adamović , Antun Milas","doi":"10.1016/j.aim.2025.110763","DOIUrl":"10.1016/j.aim.2025.110763","url":null,"abstract":"<div><div>We construct a family of potentially quasi-lisse (non-rational) vertex algebras, denoted by <span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span>, <span><math><mi>p</mi><mo>≥</mo><mn>2</mn></math></span>, which are closely related to the vertex algebra of chiral differential operators on <span><math><mi>S</mi><mi>L</mi><mo>(</mo><mn>2</mn><mo>)</mo></math></span> at level <span><math><mo>−</mo><mn>2</mn><mo>+</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mi>p</mi></mrow></mfrac></math></span>. We prove that for <span><math><mi>p</mi><mo>=</mo><mn>3</mn></math></span>, there is an isomorphism between <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> and the affine vertex algebra <span><math><msub><mrow><mi>L</mi></mrow><mrow><mo>−</mo><mn>5</mn><mo>/</mo><mn>3</mn></mrow></msub><mo>(</mo><msub><mrow><mi>g</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span> from the Cvitanović-Deligne series. Moreover, we also establish isomorphisms between <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>5</mn></mrow></msub></math></span> and certain affine <em>W</em>-algebras of types <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>E</mi></mrow><mrow><mn>8</mn></mrow></msub></math></span>, respectively. In this way, we resolve the problem of decomposing certain conformal embeddings of affine vertex algebras into affine <em>W</em>-algebras. An important feature is that <span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span> is <span><math><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><msub><mrow><mi>Z</mi></mrow><mrow><mo>≥</mo><mn>0</mn></mrow></msub></math></span>-graded with finite-dimensional graded subspaces and convergent characters. Therefore, for all <span><math><mi>p</mi><mo>≥</mo><mn>2</mn></math></span>, we show that the characters of <span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span> exhibit modularity, supporting the conjectural quasi-lisse property.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110763"},"PeriodicalIF":1.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927995","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 : 2026-01-08DOI: 10.1016/j.aim.2025.110776
Sigrid Grepstad , Mihail N. Kolountzakis
We prove that for any two lattices of the same volume there exists a measurable, bounded, common fundamental domain of them. In other words, there exists a bounded measurable set such that E tiles when translated by L or by M. A consequence of this is that the indicator function of E forms a Weyl–Heisenberg (Gabor) orthogonal basis of when translated by L and modulated by , the dual lattice of M.
{"title":"Bounded common fundamental domains for two lattices","authors":"Sigrid Grepstad , Mihail N. Kolountzakis","doi":"10.1016/j.aim.2025.110776","DOIUrl":"10.1016/j.aim.2025.110776","url":null,"abstract":"<div><div>We prove that for any two lattices <span><math><mi>L</mi><mo>,</mo><mi>M</mi><mo>⊆</mo><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span> of the same volume there exists a measurable, bounded, common fundamental domain of them. In other words, there exists a bounded measurable set <span><math><mi>E</mi><mo>⊆</mo><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span> such that <em>E</em> tiles <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span> when translated by <em>L</em> or by <em>M</em>. A consequence of this is that the indicator function of <em>E</em> forms a Weyl–Heisenberg (Gabor) orthogonal basis of <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup><mo>)</mo></math></span> when translated by <em>L</em> and modulated by <span><math><msup><mrow><mi>M</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span>, the dual lattice of <em>M</em>.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110776"},"PeriodicalIF":1.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928073","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 : 2026-01-08DOI: 10.1016/j.aim.2025.110764
Fabio Tanania
The main goal of this paper is to study relative versions of the category of modules over the isotropic motivic Brown-Peterson spectrum, with a particular emphasis on their cellular subcategories. Using techniques developed by Levine, we equip these categories with motivic t-structures, whose hearts are Tannakian categories over . This allows to define isotropic motivic fundamental groups, and to interpret relative isotropic Tate motives in the heart as their representations. Moreover, we compute these groups in the cases of the punctured projective line and split tori. Finally, we also apply Spitzweck's derived approach to establish an identification between relative isotropic Tate motives and representations of certain affine derived group schemes, whose 0-truncations coincide with the aforementioned isotropic motivic fundamental groups.
{"title":"Isotropic motivic fundamental groups","authors":"Fabio Tanania","doi":"10.1016/j.aim.2025.110764","DOIUrl":"10.1016/j.aim.2025.110764","url":null,"abstract":"<div><div>The main goal of this paper is to study relative versions of the category of modules over the isotropic motivic Brown-Peterson spectrum, with a particular emphasis on their cellular subcategories. Using techniques developed by Levine, we equip these categories with motivic <em>t</em>-structures, whose hearts are Tannakian categories over <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. This allows to define isotropic motivic fundamental groups, and to interpret relative isotropic Tate motives in the heart as their representations. Moreover, we compute these groups in the cases of the punctured projective line and split tori. Finally, we also apply Spitzweck's derived approach to establish an identification between relative isotropic Tate motives and representations of certain affine derived group schemes, whose 0-truncations coincide with the aforementioned isotropic motivic fundamental groups.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110764"},"PeriodicalIF":1.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928071","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 : 2026-01-08DOI: 10.1016/j.aim.2025.110775
Matej Filip
We establish a correspondence between one-parameter deformations of an affine Gorenstein toric pair , defined by a polytope P, and mutations of a Laurent polynomial f with Newton polytope . For a Laurent polynomial f in two variables, we construct a formal deformation of the three-dimensional Gorenstein toric pair over , where is the set of deformation parameters arising from mutations. The general fibre of this deformation is smooth if and only if f is 0-mutable. The Kodaira–Spencer map of the constructed deformation is injective, and if f is maximally mutable, then the deformation cannot be nontrivially extended to a larger smooth base space.
{"title":"Laurent polynomials and deformations of non-isolated Gorenstein toric singularities","authors":"Matej Filip","doi":"10.1016/j.aim.2025.110775","DOIUrl":"10.1016/j.aim.2025.110775","url":null,"abstract":"<div><div>We establish a correspondence between one-parameter deformations of an affine Gorenstein toric pair <span><math><mo>(</mo><msub><mrow><mi>X</mi></mrow><mrow><mi>P</mi></mrow></msub><mo>,</mo><mo>∂</mo><msub><mrow><mi>X</mi></mrow><mrow><mi>P</mi></mrow></msub><mo>)</mo></math></span>, defined by a polytope <em>P</em>, and mutations of a Laurent polynomial <em>f</em> with Newton polytope <span><math><mi>Δ</mi><mo>(</mo><mi>f</mi><mo>)</mo><mo>=</mo><mi>P</mi></math></span>. For a Laurent polynomial <em>f</em> in two variables, we construct a formal deformation of the three-dimensional Gorenstein toric pair <span><math><mo>(</mo><msub><mrow><mi>X</mi></mrow><mrow><mi>Δ</mi><mo>(</mo><mi>f</mi><mo>)</mo></mrow></msub><mo>,</mo><mo>∂</mo><msub><mrow><mi>X</mi></mrow><mrow><mi>Δ</mi><mo>(</mo><mi>f</mi><mo>)</mo></mrow></msub><mo>)</mo></math></span> over <span><math><mi>C</mi><mo>[</mo><mo>[</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>]</mo><mo>]</mo></math></span>, where <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span> is the set of deformation parameters arising from mutations. The general fibre of this deformation is smooth if and only if <em>f</em> is 0-mutable. The Kodaira–Spencer map of the constructed deformation is injective, and if <em>f</em> is maximally mutable, then the deformation cannot be nontrivially extended to a larger smooth base space.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110775"},"PeriodicalIF":1.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928077","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 : 2026-01-08DOI: 10.1016/j.aim.2025.110772
Marcin Bownik
Akemann and Weaver [3] showed Lyapunov-type theorem for rank one positive semidefinite matrices which is an extension of Weaver's KS2 conjecture [34] that was proven by Marcus, Spielman, and Srivastava [30] in their breakthrough solution of the Kadison-Singer problem [27]. They conjectured that a similar result holds for higher rank matrices. We prove the conjecture of Akemann and Weaver by establishing Lyapunov-type theorem for trace class operators. In the process we prove a matrix discrepancy result for sums of hermitian matrices. This extends rank one result of Kyng, Luh, and Song [28] who established an improved bound in Lyapunov-type theorem of Akemann and Weaver.
Akemann和Weaver[3]给出了秩一正半定矩阵的lyapunov型定理,该定理是Marcus、Spielman和Srivastava[30]在他们对kadson - singer问题[27]的突破性解中证明的Weaver的KS2猜想[34]的推广。他们推测,类似的结果也适用于更高秩的矩阵。通过建立迹类算子的lyapunov型定理,证明了Akemann和Weaver的猜想。在此过程中,我们证明了厄米矩阵和的一个矩阵差异结果。这推广了king, Luh, and Song b[28]在Akemann和Weaver的lyapunov型定理中建立了改进界的第一个结果。
{"title":"On Akemann-Weaver conjecture","authors":"Marcin Bownik","doi":"10.1016/j.aim.2025.110772","DOIUrl":"10.1016/j.aim.2025.110772","url":null,"abstract":"<div><div>Akemann and Weaver <span><span>[3]</span></span> showed Lyapunov-type theorem for rank one positive semidefinite matrices which is an extension of Weaver's KS<sub>2</sub> conjecture <span><span>[34]</span></span> that was proven by Marcus, Spielman, and Srivastava <span><span>[30]</span></span> in their breakthrough solution of the Kadison-Singer problem <span><span>[27]</span></span>. They conjectured that a similar result holds for higher rank matrices. We prove the conjecture of Akemann and Weaver by establishing Lyapunov-type theorem for trace class operators. In the process we prove a matrix discrepancy result for sums of hermitian matrices. This extends rank one result of Kyng, Luh, and Song <span><span>[28]</span></span> who established an improved bound in Lyapunov-type theorem of Akemann and Weaver.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110772"},"PeriodicalIF":1.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927996","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 : 2026-01-08DOI: 10.1016/j.aim.2025.110778
Tom Benhamou , Gabriel Goldberg
A simple -point on a regular cardinal κ is a uniform ultrafilter on κ with a mod-bounded decreasing generating sequence of length λ. We prove that if there is a simple -point ultrafilter over , then . We show that such ultrafilters appear in the models of [3], [13]. We improve the lower bound for the consistency strength of the existence of a -point to a 2-strong cardinal. Finally, we apply our arguments to obtain non-trivial lower bounds for (1) the statement that the generalized tower number is greater than and κ is measurable, (2) the preservation of measurability after the generalized Mathias forcing, and (3) variations of filter games of [28], [22], [18] in the case .
{"title":"Measures that violate the generalized continuum hypothesis","authors":"Tom Benhamou , Gabriel Goldberg","doi":"10.1016/j.aim.2025.110778","DOIUrl":"10.1016/j.aim.2025.110778","url":null,"abstract":"<div><div>A simple <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>λ</mi></mrow></msub></math></span>-point on a regular cardinal <em>κ</em> is a uniform ultrafilter on <em>κ</em> with a mod-bounded decreasing generating sequence of length <em>λ</em>. We prove that if there is a simple <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>λ</mi></mrow></msub></math></span>-point ultrafilter over <span><math><mi>κ</mi><mo>></mo><mi>ω</mi></math></span>, then <span><math><mi>λ</mi><mo>=</mo><msub><mrow><mi>d</mi></mrow><mrow><mi>κ</mi></mrow></msub><mo>=</mo><msub><mrow><mi>b</mi></mrow><mrow><mi>κ</mi></mrow></msub><mo>=</mo><msub><mrow><mi>u</mi></mrow><mrow><mi>κ</mi></mrow></msub><mo>=</mo><msub><mrow><mi>r</mi></mrow><mrow><mi>κ</mi></mrow></msub><mo>=</mo><msub><mrow><mi>s</mi></mrow><mrow><mi>κ</mi></mrow></msub></math></span>. We show that such ultrafilters appear in the models of <span><span>[3]</span></span>, <span><span>[13]</span></span>. We improve the lower bound for the consistency strength of the existence of a <span><math><msub><mrow><mi>P</mi></mrow><mrow><msup><mrow><mi>κ</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msup></mrow></msub></math></span>-point to a 2-strong cardinal. Finally, we apply our arguments to obtain non-trivial lower bounds for (1) the statement that the generalized tower number <span><math><msub><mrow><mi>t</mi></mrow><mrow><mi>κ</mi></mrow></msub></math></span> is greater than <span><math><msup><mrow><mi>κ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span> and <em>κ</em> is measurable, (2) the preservation of measurability after the generalized Mathias forcing, and (3) variations of filter games of <span><span>[28]</span></span>, <span><span>[22]</span></span>, <span><span>[18]</span></span> in the case <span><math><msup><mrow><mn>2</mn></mrow><mrow><mi>κ</mi></mrow></msup><mo>></mo><msup><mrow><mi>κ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110778"},"PeriodicalIF":1.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928078","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 : 2026-01-07DOI: 10.1016/j.aim.2025.110769
Dong Li , Ping Zhang
<div><div>We analyze the instantaneous growth of analyticity radius for three dimensional generalized Navier-Stokes equations. For the subcritical <span><math><msup><mrow><mi>H</mi></mrow><mrow><mi>γ</mi></mrow></msup><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></math></span> case with <span><math><mi>γ</mi><mo>></mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></math></span>, we prove that there exists a positive time <span><math><msub><mrow><mi>t</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> so that for any <span><math><mi>t</mi><mo>∈</mo><mo>]</mo><mn>0</mn><mo>,</mo><msub><mrow><mi>t</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>]</mo></math></span>, the radius of analyticity of the solution <em>u</em> satisfies the pointwise-in-time lower bound<span><span><span><math><mrow><mi>rad</mi></mrow><mo>(</mo><mi>u</mi><mo>)</mo><mo>(</mo><mi>t</mi><mo>)</mo><mo>≥</mo><msqrt><mrow><mo>(</mo><mn>2</mn><mi>γ</mi><mo>−</mo><mn>1</mn><mo>)</mo><mi>t</mi><mo>(</mo><mo>|</mo><mi>ln</mi><mo></mo><mi>t</mi><mo>|</mo><mo>+</mo><mi>ln</mi><mo></mo><mo>|</mo><mi>ln</mi><mo></mo><mi>t</mi><mo>|</mo><mo>+</mo><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>)</mo></mrow></msqrt><mo>,</mo></math></span></span></span> where <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>→</mo><mo>∞</mo></math></span> as <span><math><mi>t</mi><mo>→</mo><msup><mrow><mn>0</mn></mrow><mrow><mo>+</mo></mrow></msup></math></span>. This in particular gives a nontrivial improvement of the previous result by Herbst and Skibsted in <span><span>[17]</span></span> for the case <span><math><mi>γ</mi><mo>∈</mo><mo>]</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>/</mo><mn>2</mn><mo>[</mo></math></span> and also settles the decade-long open question in <span><span>[17]</span></span>, namely, whether or not<span><span><span><math><munder><mrow><mrow><mi>lim</mi></mrow><mspace></mspace><mrow><mi>inf</mi></mrow></mrow><mrow><mi>t</mi><mo>→</mo><msup><mrow><mn>0</mn></mrow><mrow><mo>+</mo></mrow></msup></mrow></munder><mspace></mspace><mfrac><mrow><mrow><mi>rad</mi></mrow><mo>(</mo><mi>u</mi><mo>)</mo><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mrow><msqrt><mrow><mi>t</mi><mo>|</mo><mi>ln</mi><mo></mo><mi>t</mi><mo>|</mo></mrow></msqrt></mrow></mfrac><mo>≥</mo><msqrt><mrow><mn>2</mn><mi>γ</mi><mo>−</mo><mn>1</mn></mrow></msqrt></math></span></span></span> for all <span><math><mi>γ</mi><mo>≥</mo><mfrac><mrow><mn>3</mn></mrow><mrow><mn>2</mn></mrow></mfrac></math></span>. In the critical case <span><math><msup><mrow><mi>H</mi></mrow><mrow><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></msup><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></math></span> we prove that there exists <span><math><msub><mrow><mi>t</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>></mo><mn>0</mn></math></span> so that for any <span><math><mi>t</mi><mo>∈</mo><mo>
{"title":"On the refined analyticity radius of 3-D generalized Navier-Stokes equations","authors":"Dong Li , Ping Zhang","doi":"10.1016/j.aim.2025.110769","DOIUrl":"10.1016/j.aim.2025.110769","url":null,"abstract":"<div><div>We analyze the instantaneous growth of analyticity radius for three dimensional generalized Navier-Stokes equations. For the subcritical <span><math><msup><mrow><mi>H</mi></mrow><mrow><mi>γ</mi></mrow></msup><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></math></span> case with <span><math><mi>γ</mi><mo>></mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></math></span>, we prove that there exists a positive time <span><math><msub><mrow><mi>t</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> so that for any <span><math><mi>t</mi><mo>∈</mo><mo>]</mo><mn>0</mn><mo>,</mo><msub><mrow><mi>t</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>]</mo></math></span>, the radius of analyticity of the solution <em>u</em> satisfies the pointwise-in-time lower bound<span><span><span><math><mrow><mi>rad</mi></mrow><mo>(</mo><mi>u</mi><mo>)</mo><mo>(</mo><mi>t</mi><mo>)</mo><mo>≥</mo><msqrt><mrow><mo>(</mo><mn>2</mn><mi>γ</mi><mo>−</mo><mn>1</mn><mo>)</mo><mi>t</mi><mo>(</mo><mo>|</mo><mi>ln</mi><mo></mo><mi>t</mi><mo>|</mo><mo>+</mo><mi>ln</mi><mo></mo><mo>|</mo><mi>ln</mi><mo></mo><mi>t</mi><mo>|</mo><mo>+</mo><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>)</mo></mrow></msqrt><mo>,</mo></math></span></span></span> where <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>→</mo><mo>∞</mo></math></span> as <span><math><mi>t</mi><mo>→</mo><msup><mrow><mn>0</mn></mrow><mrow><mo>+</mo></mrow></msup></math></span>. This in particular gives a nontrivial improvement of the previous result by Herbst and Skibsted in <span><span>[17]</span></span> for the case <span><math><mi>γ</mi><mo>∈</mo><mo>]</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>/</mo><mn>2</mn><mo>[</mo></math></span> and also settles the decade-long open question in <span><span>[17]</span></span>, namely, whether or not<span><span><span><math><munder><mrow><mrow><mi>lim</mi></mrow><mspace></mspace><mrow><mi>inf</mi></mrow></mrow><mrow><mi>t</mi><mo>→</mo><msup><mrow><mn>0</mn></mrow><mrow><mo>+</mo></mrow></msup></mrow></munder><mspace></mspace><mfrac><mrow><mrow><mi>rad</mi></mrow><mo>(</mo><mi>u</mi><mo>)</mo><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mrow><msqrt><mrow><mi>t</mi><mo>|</mo><mi>ln</mi><mo></mo><mi>t</mi><mo>|</mo></mrow></msqrt></mrow></mfrac><mo>≥</mo><msqrt><mrow><mn>2</mn><mi>γ</mi><mo>−</mo><mn>1</mn></mrow></msqrt></math></span></span></span> for all <span><math><mi>γ</mi><mo>≥</mo><mfrac><mrow><mn>3</mn></mrow><mrow><mn>2</mn></mrow></mfrac></math></span>. In the critical case <span><math><msup><mrow><mi>H</mi></mrow><mrow><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></msup><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></math></span> we prove that there exists <span><math><msub><mrow><mi>t</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>></mo><mn>0</mn></math></span> so that for any <span><math><mi>t</mi><mo>∈</mo><mo>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110769"},"PeriodicalIF":1.5,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928074","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 : 2026-01-07DOI: 10.1016/j.aim.2025.110767
Tariq Syed
Cyclic coverings produce many examples of topologically contractible smooth affine complex varieties. In this paper, we study the motivic cohomology groups of cyclic coverings over algebraically closed fields of characteristic 0. In particular, we prove that in many situations Chow groups of cyclic coverings become trivial after tensoring with . Furthermore, we can prove that the Chow groups of certain bicyclic coverings are trivial even without tensoring with .
{"title":"Motivic cohomology of cyclic coverings","authors":"Tariq Syed","doi":"10.1016/j.aim.2025.110767","DOIUrl":"10.1016/j.aim.2025.110767","url":null,"abstract":"<div><div>Cyclic coverings produce many examples of topologically contractible smooth affine complex varieties. In this paper, we study the motivic cohomology groups of cyclic coverings over algebraically closed fields of characteristic 0. In particular, we prove that in many situations Chow groups of cyclic coverings become trivial after tensoring with <span><math><mi>Q</mi></math></span>. Furthermore, we can prove that the Chow groups of certain bicyclic coverings are trivial even without tensoring with <span><math><mi>Q</mi></math></span>.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110767"},"PeriodicalIF":1.5,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928072","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 : 2026-01-07DOI: 10.1016/j.aim.2025.110766
Jifeng Chu , Gang Meng , Zhi Zhang
The aim of this paper is to study a kind of reverse spectral problems for Camassa-Holm equations. We prove the explicit solutions for the extremal -norms of the potentials, given the first fixed periodic eigenvalue or any fixed Dirichlet eigenvalue, or fixed ratios of Dirichlet eigenvalues. We use the setting of measure differential equations to understand such problems because the solution will lead to Dirac measure distributions of potentials. The explicit expressions for the sharp bounds are given as some elementary functions.
{"title":"Extremal norms of potentials from fixed eigenvalues or eigenvalues ratio for Camassa-Holm equations","authors":"Jifeng Chu , Gang Meng , Zhi Zhang","doi":"10.1016/j.aim.2025.110766","DOIUrl":"10.1016/j.aim.2025.110766","url":null,"abstract":"<div><div>The aim of this paper is to study a kind of reverse spectral problems for Camassa-Holm equations. We prove the explicit solutions for the extremal <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span>-norms of the potentials, given the first fixed periodic eigenvalue or any fixed Dirichlet eigenvalue, or fixed ratios of Dirichlet eigenvalues. We use the setting of measure differential equations to understand such problems because the solution will lead to Dirac measure distributions of potentials. The explicit expressions for the sharp bounds are given as some elementary functions.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110766"},"PeriodicalIF":1.5,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928075","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 : 2026-01-06DOI: 10.1016/j.aim.2025.110756
Ivan Cheltsov , Yuri Tschinkel , Zhijia Zhang
We study rationality properties of real singular cubic threefolds.
研究了实奇异三次三重的合理性性质。
{"title":"Rationality of singular cubic threefolds over R","authors":"Ivan Cheltsov , Yuri Tschinkel , Zhijia Zhang","doi":"10.1016/j.aim.2025.110756","DOIUrl":"10.1016/j.aim.2025.110756","url":null,"abstract":"<div><div>We study rationality properties of real singular cubic threefolds.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"487 ","pages":"Article 110756"},"PeriodicalIF":1.5,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928069","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}