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Volume functionals on pseudoconvex hypersurfaces 伪凸超曲面上的体积函数
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-04-04 DOI: 10.1142/s0129167x24410052
Simon Donaldson, Fabian Lehmann
<p>The focus of this paper is on a volume form defined on a pseudoconvex hypersurface <span><math altimg="eq-00001.gif" display="inline" overflow="scroll"><mi>M</mi></math></span><span></span> in a complex Calabi–Yau manifold (that is, a complex <span><math altimg="eq-00002.gif" display="inline" overflow="scroll"><mi>n</mi></math></span><span></span>-manifold with a nowhere-vanishing holomorphic <span><math altimg="eq-00003.gif" display="inline" overflow="scroll"><mi>n</mi></math></span><span></span>-form). We begin by defining this volume form and observing that it can be viewed as a generalization of the affine-invariant volume form on a convex hypersurface in <span><math altimg="eq-00004.gif" display="inline" overflow="scroll"><msup><mrow><mstyle><mtext mathvariant="normal">R</mtext></mstyle></mrow><mrow><mi>n</mi></mrow></msup></math></span><span></span>. We compute the first variation, which leads to a similar generalization of the affine mean curvature. In Sec. 2, we investigate the constrained variational problem, for pseudoconvex hypersurfaces <span><math altimg="eq-00005.gif" display="inline" overflow="scroll"><mi>M</mi></math></span><span></span> bounding compact domains <span><math altimg="eq-00006.gif" display="inline" overflow="scroll"><mi mathvariant="normal">Ω</mi><mo>⊂</mo><mi>Z</mi></math></span><span></span>. That is, we study critical points of the volume functional <span><math altimg="eq-00007.gif" display="inline" overflow="scroll"><mi>A</mi><mo stretchy="false">(</mo><mi>M</mi><mo stretchy="false">)</mo></math></span><span></span> where the ordinary volume <span><math altimg="eq-00008.gif" display="inline" overflow="scroll"><mi>V</mi><mo stretchy="false">(</mo><mi mathvariant="normal">Ω</mi><mo stretchy="false">)</mo></math></span><span></span> is fixed. The critical points are analogous to constant mean curvature submanifolds. We find that Sasaki–Einstein hypersurfaces satisfy the condition, and in particular the standard sphere <span><math altimg="eq-00009.gif" display="inline" overflow="scroll"><msup><mrow><mi>S</mi></mrow><mrow><mn>2</mn><mi>n</mi><mo stretchy="false">−</mo><mn>1</mn></mrow></msup><mo>⊂</mo><msup><mrow><mstyle><mtext mathvariant="normal">C</mtext></mstyle></mrow><mrow><mi>n</mi></mrow></msup></math></span><span></span> does. The main work in the paper comes in Sec. 3 where we compute the second variation about the sphere. We find that it is negative in “most” directions but non-negative in directions corresponding to deformations of <span><math altimg="eq-00010.gif" display="inline" overflow="scroll"><msup><mrow><mi>S</mi></mrow><mrow><mn>2</mn><mi>n</mi><mo stretchy="false">−</mo><mn>1</mn></mrow></msup></math></span><span></span> by holomorphic diffeomorphisms. We are led to conjecture a “minimax” characterization of the sphere. We also discuss connections with the affine geometry case and with Kähler–Einstein geometry. Our original motivation for investigating these matters came from the case <span><m
本文的重点是在复 Calabi-Yau 流形(即具有无处消失全形 n 形式的复 n 流形)中的伪凸超曲面 M 上定义的一种体积形式。我们首先定义这种体量形式,并指出它可以看作是 Rn 中凸超曲面上仿射不变体量形式的广义化。我们计算了第一个变化,这导致了仿射平均曲率的类似广义化。在第 2 节中,我们研究了以紧凑域 Ω⊂Z 为边界的伪凸超曲面 M 的约束变分问题。也就是说,我们研究的是普通体积 V(Ω) 固定的体积函数 A(M) 的临界点。临界点类似于恒定平均曲率子曲面。我们发现佐佐木-爱因斯坦超曲面满足条件,尤其是标准球 S2n-1⊂Cn 满足条件。本文的主要工作在第 3 节,我们计算了球面的第二次变化。我们发现它在 "大多数 "方向上都是负值,但在全形差分变形对应的 S2n-1 变形方向上却不是负值。我们由此猜想出球面的 "最小 "特征。我们还讨论了与仿射几何和凯勒-爱因斯坦几何的联系。我们研究这些问题的最初动机来自 n=3 的情况和我们之前论文 [S. Donaldson and F. Leinstein] 中研究的嵌入问题。Donaldson and F. Lehmann, Closed 3-forms in five dimensions and embedding problems, preprint (2022), arXiv:2210.16208].这种情况有一些特殊之处。在第 4 节中,我们将回顾这一点,并从 M 上精确 3-forms 的交映结构和 M 的差分作用的矩映射的角度发展一些理论。
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引用次数: 0
Quantization of locally compact groups associated with essentially bijective 1-cocycles 与本质上双射的 1-Cocycles 相关联的局部紧凑群的量化
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-04-03 DOI: 10.1142/s0129167x24500277
Pierre Bieliavsky, Victor Gayral, Sergey Neshveyev, Lars Tuset

Given an extension 0VGQ1 of locally compact groups, with V abelian, and a compatible essentially bijective 1-cocycle η:QV̂, we define a dual unitary 2-cocycle on G and show that the associated deformation of Ĝ is a cocycle bicrossed product defined by a matched pair of subgroups of QV̂. We also discuss an interpretation of our construction from the point of view of Kac cohomology for matched pairs. Our setup generalizes that of Etingof and Gelaki for finite groups and its extension due to Ben David and Ginosar, as well as our earlier work on locally compact groups satisfying the dual orbit condition. In particular, we get a locally compact quantum group from every involutive nondegenerate set-theoretical solution of the Yang–Baxter equation, or more generally, from every brace structure. On the technical side, the key new points are constructions of an irreducible projective representation of G on L2(Q) and a unitary quantization map L2(G)HS(L2(Q)) of Kohn–Nirenberg type.

给定局部紧密群的扩展 0→V→G→Q→1,其中 V 是无性的,以及一个相容的本质上双射的 1 循环 η:Q→V̂,我们定义了 G 上的对偶单元 2 循环,并证明Ĝ 的相关变形是由 Q⋉V ̂ 的一对匹配子群定义的循环双交积。我们还讨论了从匹配对的 Kac 同调的角度对我们的构造的解释。我们的设置概括了 Etingof 和 Gelaki 对有限群的设置、Ben David 和 Ginosar 对其的扩展,以及我们早期对满足对偶轨道条件的局部紧凑群的研究。特别是,我们从杨-巴克斯特方程的每一个渐开非enerate集合理论解,或者更广义地说,从每一个支撑结构,都可以得到一个局部紧凑的量子群。在技术方面,新的关键点在于构建了 G 在 L2(Q) 上的不可还原投影表示和 Kohn-Nirenberg 类型的单元量子化映射 L2(G)→HS(L2(Q))。
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引用次数: 0
On codimension one holomorphic distributions on compact toric orbifolds 关于紧凑环状轨道上的一维全态分布
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-04-03 DOI: 10.1142/s0129167x24500241
Arnulfo Miguel Rodríguez Peña

The number of singularities, counted with multiplicity, of a generic codimension one holomorphic distribution on a compact toric orbifold is determined. As a consequence, we provide a classification for regular distributions on rational normal scrolls and weighted projective spaces. Additionally, under specific conditions, we prove that the singular set of a codimension one holomorphic foliation on a compact toric orbifold admits at least one irreducible component of codimension two, and we also present a Darboux–Jouanolou type integrability theorem for codimension one holomorphic foliations. Our results are exemplified through various illustrative examples.

我们确定了紧凑环状轨道上一般标度为一的全形分布的奇点数(以倍率计算)。因此,我们为有理正卷和加权投影空间上的正则分布提供了一个分类。此外,在特定条件下,我们证明了紧凑环状轨道上的一维全形叶状体的奇异集至少包含一个二维不可还原分量,我们还提出了一维全形叶状体的达尔布-朱阿诺卢型可整性定理。我们的结果将通过各种示例加以说明。
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引用次数: 0
Endpoint estimates of variation and oscillation operators associated with Zλ functions 与 Zλ 函数相关的变化和振荡算子的端点估计值
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-03-28 DOI: 10.1142/s0129167x24500253
Yongming Wen, Yanyan Han, Xianming Hou

This paper obtains weak-type estimates, limiting weak-type behaviors for variation operators associated with Zλ functions. Besides, we give a new characterization of Hardy space via the boundedness of variation operators associated with Zλ functions.

本文获得了弱型估计,限制了与 Zλ 函数相关的变算子的弱型行为。此外,我们还通过与 Zλ 函数相关的变分算子的有界性给出了哈代空间的新特征。
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引用次数: 0
Twistor space for local systems on an open curve 开阔曲线上局部系统的孪生空间
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-03-27 DOI: 10.1142/s0129167x24410131
Carlos T. Simpson

Let X=X¯D be a smooth quasi-projective curve. We previously constructed a Deligne–Hitchin moduli space with Hecke gauge groupoid for connections of rank 2. We extend this construction to the case of any rank r, although still keeping a genericity hypothesis. The formal neighborhood of a preferred section corresponding to a tame harmonic bundle is governed by a mixed twistor structure.

假设 X=X¯-D 是一条光滑的准投影曲线。我们之前为秩为 2 的连接构造了一个具有 Hecke gauge groupoid 的 Deligne-Hitchin 模空间。我们将这一构造扩展到任意秩 r 的情况,但仍保留通性假设。与驯服谐波束相对应的优选截面的形式邻域受混合扭曲结构支配。
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引用次数: 0
Implosion, contraction and Moore–Tachikawa 内爆、收缩和摩尔-立川
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-03-20 DOI: 10.1142/s0129167x24410040
Andrew Dancer, Frances Kirwan, Johan Martens

We give a survey of the implosion construction, extending some of its aspects relating to hypertoric geometry from type A to a general reductive group, and interpret it in the context of the Moore–Tachikawa category. We use these ideas to discuss how the contraction construction in symplectic geometry can be generalized to the hyperkähler or complex symplectic situation.

我们考察了内爆构造,将其与高折射几何有关的某些方面从 A 型扩展到一般还原群,并在摩尔-立川范畴的背景下对其进行了解释。我们利用这些观点来讨论如何将交点几何中的内卷构造推广到超交点或复交点情形中。
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引用次数: 0
Lebesgue points of functions in the complex Sobolev space 复杂索波列夫空间中函数的勒贝格点
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-03-13 DOI: 10.1142/s0129167x24500149
Gabriel Vigny, Duc-Viet Vu

Let φ be a function in the complex Sobolev space W(U), where U is an open subset in k. We show that the complement of the set of Lebesgue points of φ is pluripolar. The key ingredient in our approach is to show that |φ|α for α[1,2) is locally bounded from above by a plurisubharmonic function.

设 φ 是复 Sobolev 空间 W∗(U)中的函数,其中 U 是ℂk 中的开放子集。我们证明φ 的 Lebesgue 点集的补集是多极的。我们的方法的关键在于证明α∈[1,2)的|φ|α从上而下局部受多次谐函数约束。
{"title":"Lebesgue points of functions in the complex Sobolev space","authors":"Gabriel Vigny, Duc-Viet Vu","doi":"10.1142/s0129167x24500149","DOIUrl":"https://doi.org/10.1142/s0129167x24500149","url":null,"abstract":"<p>Let <span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><mi>φ</mi></math></span><span></span> be a function in the complex Sobolev space <span><math altimg=\"eq-00002.gif\" display=\"inline\" overflow=\"scroll\"><msup><mrow><mi>W</mi></mrow><mrow><mo stretchy=\"false\">∗</mo></mrow></msup><mo stretchy=\"false\">(</mo><mi>U</mi><mo stretchy=\"false\">)</mo></math></span><span></span>, where <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><mi>U</mi></math></span><span></span> is an open subset in <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><msup><mrow><mi>ℂ</mi></mrow><mrow><mi>k</mi></mrow></msup></math></span><span></span>. We show that the complement of the set of Lebesgue points of <span><math altimg=\"eq-00005.gif\" display=\"inline\" overflow=\"scroll\"><mi>φ</mi></math></span><span></span> is pluripolar. The key ingredient in our approach is to show that <span><math altimg=\"eq-00006.gif\" display=\"inline\" overflow=\"scroll\"><mo>|</mo><mi>φ</mi><msup><mrow><mo>|</mo></mrow><mrow><mi>α</mi></mrow></msup></math></span><span></span> for <span><math altimg=\"eq-00007.gif\" display=\"inline\" overflow=\"scroll\"><mi>α</mi><mo>∈</mo><mo stretchy=\"false\">[</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo stretchy=\"false\">)</mo></math></span><span></span> is locally bounded from above by a plurisubharmonic function.</p>","PeriodicalId":54951,"journal":{"name":"International Journal of Mathematics","volume":"31 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140154580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A characterization of quasipositive two-bridge knots 准正二桥结的特征描述
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-03-02 DOI: 10.1142/s0129167x24500150
Burak Ozbagci, Stepan Orevkov

We prove a simple necessary and sufficient condition for a two-bridge knot K(p,q) to be quasipositive, based on the continued fraction expansion of p/q. As an application, coupled with some classification results in contact and symplectic topology, we give a new proof of the fact that smoothly slice two-bridge knots are non-quasipositive. Another proof of this fact using methods within the scope of knot theory is presented in Appendix A, by Stepan Orevkov.

我们基于 p/q 的连续分数展开,证明了双桥结 K(p,q) 为准正数的一个简单必要条件和充分条件。作为应用,结合接触拓扑学和交点拓扑学中的一些分类结果,我们给出了平滑切分二桥结为非类正结的新证明。斯捷潘-奥列夫科夫(Stepan Orevkov)在附录 A 中给出了另一个使用结理论方法的证明。
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引用次数: 0
Finsler metrizabilities and geodesic invariance 芬斯勒元可变性和测地不变性
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-02-28 DOI: 10.1142/s0129167x24500162
Ioan Bucataru, Oana Constantinescu

We demonstrate that various metrizability problems for Finsler sprays can be reformulated in terms of the geodesic invariance of two tensors, namely the metric and angular tensors. We show that a spray S is the geodesic spray of some Finsler metric if and only if its metric tensor is geodesically invariant. Moreover, we establish that gyroscopic sprays constitute the largest class of sprays characterized by a geodesic-invariant angular metric. Scalar functions associated with these geodesically invariant tensors will also be invariant, thereby providing first integrals for the given spray.

我们证明,可以用两个张量(即度量张量和角度张量)的大地不变性来重新表述芬斯勒喷雾的各种可元性问题。我们证明,当且仅当一个喷雾 S 的度量张量具有大地不变性时,它就是某个 Finsler 度量的大地喷雾。此外,我们还确定陀螺喷雾构成了以大地不变角度量为特征的最大一类喷雾。与这些大地不变张量相关的标量函数也将是不变的,从而为给定的喷雾提供第一积分。
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引用次数: 0
Equivariant spectral flow and equivariant η-invariants on manifolds with boundary 有边界流形上的等变谱流和等变η变量
IF 0.6 4区 数学 Q3 MATHEMATICS Pub Date : 2024-02-14 DOI: 10.1142/s0129167x2450006x
Johnny Lim, Hang Wang

In this paper, we study several closely related invariants associated to Dirac operators on odd-dimensional manifolds with boundary with an action of the compact group H of isometries. In particular, the equality between equivariant winding numbers, equivariant spectral flow and equivariant Maslov indices is established. We also study equivariant η-invariants which play a fundamental role in the equivariant analog of Getzler’s spectral flow formula. As a consequence, we establish a relation between equivariant η-invariants and equivariant Maslov triple indices in the splitting of manifolds.

在本文中,我们研究了与奇维流形上的狄拉克算子相关的几个密切相关的不变式,这些奇维流形的边界具有紧凑组 H 的等效作用。特别是,我们建立了等变缠绕数、等变谱流和等变马斯洛夫指数之间的相等关系。我们还研究了等变量 η-不变式,它在格茨勒谱流公式的等变量类比中起着基本作用。因此,我们在流形分裂中建立了等η变量与等马斯洛夫三指数之间的关系。
{"title":"Equivariant spectral flow and equivariant η-invariants on manifolds with boundary","authors":"Johnny Lim, Hang Wang","doi":"10.1142/s0129167x2450006x","DOIUrl":"https://doi.org/10.1142/s0129167x2450006x","url":null,"abstract":"<p>In this paper, we study several closely related invariants associated to Dirac operators on odd-dimensional manifolds with boundary with an action of the compact group <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><mi>H</mi></math></span><span></span> of isometries. In particular, the equality between equivariant winding numbers, equivariant spectral flow and equivariant Maslov indices is established. We also study equivariant <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><mi>η</mi></math></span><span></span>-invariants which play a fundamental role in the equivariant analog of Getzler’s spectral flow formula. As a consequence, we establish a relation between equivariant <span><math altimg=\"eq-00005.gif\" display=\"inline\" overflow=\"scroll\"><mi>η</mi></math></span><span></span>-invariants and equivariant Maslov triple indices in the splitting of manifolds.</p>","PeriodicalId":54951,"journal":{"name":"International Journal of Mathematics","volume":"24 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140154653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
期刊
International Journal of Mathematics
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