Pub Date : 2024-06-06DOI: 10.1007/s00208-024-02903-y
Lindsay Dever
Ambient prime geodesic theorems provide an asymptotic count of closed geodesics by their length and holonomy and imply effective equidistribution of holonomy. We show that for a smoothed count of closed geodesics on compact hyperbolic 3-manifolds, there is a persistent bias in the secondary term which is controlled by the number of zero spectral parameters. In addition, we show that a normalized, smoothed bias count is distributed according to a probability distribution, which we explicate when all distinct, non-zero spectral parameters are linearly independent.
{"title":"Bias in the distribution of holonomy on compact hyperbolic 3-manifolds","authors":"Lindsay Dever","doi":"10.1007/s00208-024-02903-y","DOIUrl":"https://doi.org/10.1007/s00208-024-02903-y","url":null,"abstract":"<p>Ambient prime geodesic theorems provide an asymptotic count of closed geodesics by their length and holonomy and imply effective equidistribution of holonomy. We show that for a smoothed count of closed geodesics on compact hyperbolic 3-manifolds, there is a persistent bias in the secondary term which is controlled by the number of zero spectral parameters. In addition, we show that a normalized, smoothed bias count is distributed according to a probability distribution, which we explicate when all distinct, non-zero spectral parameters are linearly independent.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"27 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141512657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article studies the canonical Hilbert energy (H^{s/2}(M)) on a Riemannian manifold for (sin (0,2)), with particular focus on the case of closed manifolds. Several equivalent definitions for this energy and the fractional Laplacian on a manifold are given, and they are shown to be identical up to explicit multiplicative constants. Moreover, the precise behavior of the kernel associated with the singular integral definition of the fractional Laplacian is obtained through an in-depth study of the heat kernel on a Riemannian manifold. Furthermore, a monotonicity formula for stationary points of functionals of the type ({mathcal {E}}(v)=[v]^2_{H^{s/2}(M)}+int _M F(v) , dV), with (Fge 0), is given, which includes in particular the case of nonlocal s-minimal surfaces. Finally, we prove some estimates for the Caffarelli–Silvestre extension problem, which are of general interest. This work is motivated by Caselli et al. (Yau’s conjecture for nonlocal minimal surfaces, arxiv preprint, 2023), which defines nonlocal minimal surfaces on closed Riemannian manifolds and shows the existence of infinitely many of them for any metric on the manifold, ultimately proving the nonlocal version of a conjecture of Yau (Ann Math Stud 102:669–706, 1982). Indeed, the definitions and results in the present work serve as an essential technical toolbox for the results in Caselli et al. (Yau’s conjecture for nonlocal minimal surfaces, arxiv preprint, 2023).
这篇文章研究了黎曼流形上的(sin (0,2))的典型希尔伯特能(H^{s/2}(M)),尤其关注封闭流形的情况。给出了该能量与流形上分数拉普拉奇的几个等价定义,并证明它们在明确的乘法常数范围内是相同的。此外,通过深入研究黎曼流形上的热核,还获得了与分数拉普拉奇奇异积分定义相关的核的精确行为。此外,我们还给出了具有 (Fge 0) 的函数类型 ({mathcal {E}}(v)=[v]^2_{H^{s/2}(M)}+int _M F(v) , dV) 的静止点的单调性公式,其中特别包括非局部 s 最小曲面的情况。最后,我们证明了对 Caffarelli-Silvestre 扩展问题的一些估计,这些估计具有普遍意义。这项工作受 Caselli 等人(Yau's conjecture for nonlocal minimal surfaces, arxiv preprint, 2023)的启发,他们定义了封闭黎曼流形上的非局部极小曲面,并证明了对于流形上的任意度量,存在无限多的非局部极小曲面,最终证明了 Yau 猜想的非局部版本(Ann Math Stud 102:669-706, 1982)。事实上,本研究中的定义和结果是卡塞利等人(Yau's conjecture for nonlocal minimal surfaces, arxiv preprint, 2023)成果的重要技术工具箱。
{"title":"Fractional Sobolev spaces on Riemannian manifolds","authors":"Michele Caselli, Enric Florit-Simon, Joaquim Serra","doi":"10.1007/s00208-024-02894-w","DOIUrl":"https://doi.org/10.1007/s00208-024-02894-w","url":null,"abstract":"<p>This article studies the canonical Hilbert energy <span>(H^{s/2}(M))</span> on a Riemannian manifold for <span>(sin (0,2))</span>, with particular focus on the case of closed manifolds. Several equivalent definitions for this energy and the fractional Laplacian on a manifold are given, and they are shown to be identical up to explicit multiplicative constants. Moreover, the precise behavior of the kernel associated with the singular integral definition of the fractional Laplacian is obtained through an in-depth study of the heat kernel on a Riemannian manifold. Furthermore, a monotonicity formula for stationary points of functionals of the type <span>({mathcal {E}}(v)=[v]^2_{H^{s/2}(M)}+int _M F(v) , dV)</span>, with <span>(Fge 0)</span>, is given, which includes in particular the case of nonlocal <i>s</i>-minimal surfaces. Finally, we prove some estimates for the Caffarelli–Silvestre extension problem, which are of general interest. This work is motivated by Caselli et al. (Yau’s conjecture for nonlocal minimal surfaces, arxiv preprint, 2023), which defines nonlocal minimal surfaces on closed Riemannian manifolds and shows the existence of infinitely many of them for any metric on the manifold, ultimately proving the nonlocal version of a conjecture of Yau (Ann Math Stud 102:669–706, 1982). Indeed, the definitions and results in the present work serve as an essential technical toolbox for the results in Caselli et al. (Yau’s conjecture for nonlocal minimal surfaces, arxiv preprint, 2023).</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"35 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141259069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1007/s00208-024-02898-6
Takwon Kim, Ki-Ahm Lee, Hyungsung Yun
In this paper, we study generalized Schauder theory for the degenerate/singular parabolic equations of the form
$$begin{aligned} u_t = a^{i'j'}u_{i'j'} + 2 x_n^{gamma /2} a^{i'n} u_{i'n} + x_n^{gamma } a^{nn} u_{nn} + b^{i'} u_{i'} + x_n^{gamma /2} b^n u_{n} + c u + f quad (gamma le 1). end{aligned}$$
When the equation above is singular, it can be derived from Monge–Ampère equations by using the partial Legendre transform. Also, we study the fractional version of Taylor expansion for the solution u, which is called s-polynomial. To prove (C_s^{2+alpha })-regularity and higher regularity of the solution u, we establish generalized Schauder theory which approximates coefficients of the operator with s-polynomials rather than constants. The generalized Schauder theory not only recovers the proof for uniformly parabolic equations but is also applicable to other operators that are difficult to apply the bootstrap argument to obtain higher regularity.
本文研究了形式为 $$begin{aligned} u_t = a^{i'j'}u_{i'j'} 的退化/奇异抛物方程的广义绍德理论。+ 2 x_n^{gamma /2} a^{i'n} u_{i'n}+ x_n^{gamma } a^{nn} u_{nn}+ b^{i'} u_{i'}+ x_n^{gamma /2} b^n u_{n}+ c u + f quad (gamma le 1).end{aligned}$$当上面的方程是奇异方程时,它可以通过部分 Legendre 变换从 Monge-Ampère 方程中导出。此外,我们还研究了解 u 的分数版泰勒展开,即 s 多项式。为了证明解 u 的 (C_s^{2+alpha })-regularity 和更高的正则性,我们建立了广义的 Schauder 理论,该理论用 s-polynomial 而不是常数来逼近算子的系数。广义绍德理论不仅恢复了均匀抛物方程的证明,而且适用于其他难以应用引导论证获得高正则性的算子。
{"title":"Generalized Schauder theory and its application to degenerate/singular parabolic equations","authors":"Takwon Kim, Ki-Ahm Lee, Hyungsung Yun","doi":"10.1007/s00208-024-02898-6","DOIUrl":"https://doi.org/10.1007/s00208-024-02898-6","url":null,"abstract":"<p>In this paper, we study generalized Schauder theory for the degenerate/singular parabolic equations of the form </p><span>$$begin{aligned} u_t = a^{i'j'}u_{i'j'} + 2 x_n^{gamma /2} a^{i'n} u_{i'n} + x_n^{gamma } a^{nn} u_{nn} + b^{i'} u_{i'} + x_n^{gamma /2} b^n u_{n} + c u + f quad (gamma le 1). end{aligned}$$</span><p>When the equation above is singular, it can be derived from Monge–Ampère equations by using the partial Legendre transform. Also, we study the fractional version of Taylor expansion for the solution <i>u</i>, which is called <i>s</i>-polynomial. To prove <span>(C_s^{2+alpha })</span>-regularity and higher regularity of the solution <i>u</i>, we establish generalized Schauder theory which approximates coefficients of the operator with <i>s</i>-polynomials rather than constants. The generalized Schauder theory not only recovers the proof for uniformly parabolic equations but is also applicable to other operators that are difficult to apply the bootstrap argument to obtain higher regularity.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"53 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141258908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1007/s00208-024-02904-x
Marcelo M. Cavalcanti, Valéria N. Domingos Cavalcanti, André Vicente
We study the stabilization and the well-posedness of solutions of the quintic wave equation with locally distributed damping. The novelty of this paper is that we deal with the difficulty that the main equation does not have good nonlinear structure amenable to a direct proof of a priori bounds and a desirable observability inequality. It is well known that observability inequalities play a critical role in characterizing the long time behaviour of solutions of evolution equations, which is the main goal of this study. In order to address this, we approximate weak solutions for regular solutions for which it is possible to obtain a priori bounds and prove the essential observability inequality. The treatment of these approximate solutions is still a challenging task and requires the use of Strichartz estimates and some microlocal analysis tools such as microlocal defect measures.
{"title":"Exponential decay for the quintic wave equation with locally distributed damping","authors":"Marcelo M. Cavalcanti, Valéria N. Domingos Cavalcanti, André Vicente","doi":"10.1007/s00208-024-02904-x","DOIUrl":"https://doi.org/10.1007/s00208-024-02904-x","url":null,"abstract":"<p>We study the stabilization and the well-posedness of solutions of the quintic wave equation with locally distributed damping. The novelty of this paper is that we deal with the difficulty that the main equation does not have good nonlinear structure amenable to a direct proof of a priori bounds and a desirable observability inequality. It is well known that observability inequalities play a critical role in characterizing the long time behaviour of solutions of evolution equations, which is the main goal of this study. In order to address this, we approximate weak solutions for regular solutions for which it is possible to obtain a priori bounds and prove the essential observability inequality. The treatment of these approximate solutions is still a challenging task and requires the use of Strichartz estimates and some microlocal analysis tools such as microlocal defect measures.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"30 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141259060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-02DOI: 10.1007/s00208-024-02906-9
Irving Dai, Jennifer Hom, Matthew Stoffregen, Linh Truong
We study the homology concordance group of knots in integer homology three-spheres which bound integer homology four-balls. Using knot Floer homology, we construct an infinite number of (mathbb {Z})-valued, linearly independent homology concordance homomorphisms which vanish for knots coming from (S^3). This shows that the homology concordance group modulo knots coming from (S^3) contains an infinite-rank summand. The techniques used here generalize the classification program established in previous papers regarding the local equivalence group of knot Floer complexes over (mathbb {F}[U, V]/(UV)). Our results extend this approach to complexes defined over a broader class of rings.
{"title":"Homology concordance and knot Floer homology","authors":"Irving Dai, Jennifer Hom, Matthew Stoffregen, Linh Truong","doi":"10.1007/s00208-024-02906-9","DOIUrl":"https://doi.org/10.1007/s00208-024-02906-9","url":null,"abstract":"<p>We study the homology concordance group of knots in integer homology three-spheres which bound integer homology four-balls. Using knot Floer homology, we construct an infinite number of <span>(mathbb {Z})</span>-valued, linearly independent homology concordance homomorphisms which vanish for knots coming from <span>(S^3)</span>. This shows that the homology concordance group modulo knots coming from <span>(S^3)</span> contains an infinite-rank summand. The techniques used here generalize the classification program established in previous papers regarding the local equivalence group of knot Floer complexes over <span>(mathbb {F}[U, V]/(UV))</span>. Our results extend this approach to complexes defined over a broader class of rings.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"327 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.1007/s00208-024-02893-x
Jiao Chen, Danqing He, Guozhen Lu, Bae Jun Park, Lu Zhang
In this paper, we investigate the Hörmander type theorems for the multi-linear and multi-parameter Fourier multipliers. When the multipliers are characterized by (L^u)-based Sobolev norms for (1<ule 2), our results on the smoothness assumptions are sharp in the multi-parameter and bilinear case. In the multi-parameter and multi-linear case, our results are almost sharp. Moreover, even in the one-parameter and multi-linear case, our results improve earlier ones in the literature.
{"title":"A sharp Hörmander estimate for multi-parameter and multi-linear Fourier multiplier operators","authors":"Jiao Chen, Danqing He, Guozhen Lu, Bae Jun Park, Lu Zhang","doi":"10.1007/s00208-024-02893-x","DOIUrl":"https://doi.org/10.1007/s00208-024-02893-x","url":null,"abstract":"<p>In this paper, we investigate the Hörmander type theorems for the multi-linear and multi-parameter Fourier multipliers. When the multipliers are characterized by <span>(L^u)</span>-based Sobolev norms for <span>(1<ule 2)</span>, our results on the smoothness assumptions are sharp in the multi-parameter and bilinear case. In the multi-parameter and multi-linear case, our results are almost sharp. Moreover, even in the one-parameter and multi-linear case, our results improve earlier ones in the literature.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"46 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2023-05-13DOI: 10.1177/19433875231176339
Heather Schopper, Natalie A Krane, Kevin J Sykes, Katherine Yu, J David Kriet, Clinton D Humphrey
Study design: Retrospective chart review.
Objective: Restoration of premorbid occlusion is a key goal in the treatment of mandibular fractures. Placement of the patient in maxillomandibular fixation (MMF) is performed during mandibular fracture repair to help establish occlusion. A number of techniques are available to achieve MMF. We sought to examine trends in MMF technique at our institution.
Methods: A retrospective chart review was conducted to evaluate patients who underwent surgical treatment of mandibular fractures between January 1, 2011 and March 31, 2021. Data including fracture characteristics, mechanism of injury, patient demographics, complication rates, and MMF technique utilized were collected.
Results: One hundred sixty-three patients underwent MMF (132 males). The most common etiology of fracture was assault (34%). There was an increasing preference for rapid MMF techniques over time, as opposed to standard Erich arch bars. No significant difference in obtaining adequate fracture reduction as determined by postoperative imaging or complications were noted between those who underwent MMF with newer rapid techniques vs traditional MMF techniques.
Conclusions: Our institution has demonstrated changing trends in the technique utilized for establishing occlusion intraoperatively, more recently favoring rapid MMF techniques, with similar rates of complications and ability to adequately reduce fractures.
{"title":"Trends in Maxillomandibular Fixation Technique at a Single Academic Institution.","authors":"Heather Schopper, Natalie A Krane, Kevin J Sykes, Katherine Yu, J David Kriet, Clinton D Humphrey","doi":"10.1177/19433875231176339","DOIUrl":"10.1177/19433875231176339","url":null,"abstract":"<p><strong>Study design: </strong>Retrospective chart review.</p><p><strong>Objective: </strong>Restoration of premorbid occlusion is a key goal in the treatment of mandibular fractures. Placement of the patient in maxillomandibular fixation (MMF) is performed during mandibular fracture repair to help establish occlusion. A number of techniques are available to achieve MMF. We sought to examine trends in MMF technique at our institution.</p><p><strong>Methods: </strong>A retrospective chart review was conducted to evaluate patients who underwent surgical treatment of mandibular fractures between January 1, 2011 and March 31, 2021. Data including fracture characteristics, mechanism of injury, patient demographics, complication rates, and MMF technique utilized were collected.</p><p><strong>Results: </strong>One hundred sixty-three patients underwent MMF (132 males). The most common etiology of fracture was assault (34%). There was an increasing preference for rapid MMF techniques over time, as opposed to standard Erich arch bars. No significant difference in obtaining adequate fracture reduction as determined by postoperative imaging or complications were noted between those who underwent MMF with newer rapid techniques vs traditional MMF techniques.</p><p><strong>Conclusions: </strong>Our institution has demonstrated changing trends in the technique utilized for establishing occlusion intraoperatively, more recently favoring rapid MMF techniques, with similar rates of complications and ability to adequately reduce fractures.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"381 1","pages":"119-123"},"PeriodicalIF":0.9,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11107819/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90684266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.1007/s00208-024-02901-0
Agnid Banerjee, Nicola Garofalo, Isidro H. Munive
In his seminal 1981 study D. Jerison showed the remarkable negative phenomenon that there exist, in general, no Schauder estimates near the characteristic boundary in the Heisenberg group (mathbb {H}^{n}.) On the positive side, by adapting tools from Fourier and microlocal analysis, he developed a Schauder theory at a non-characteristic portion of the boundary, based on the non-isotropic Folland–Stein Hölder classes. On the other hand, the 1976 celebrated work of Rothschild and Stein on their lifting theorem established the central position of stratified nilpotent Lie groups (nowadays known as Carnot groups) in the analysis of Hörmander operators but, to present date, there exists no known counterpart of Jerison’s results in these sub-Riemannian ambients. In this paper we fill this gap. We prove optimal (Gamma ^{k,alpha })((kge 2)) Schauder estimates near a (C^{k,alpha }) non-characteristic portion of the boundary for (Gamma ^{k-2, alpha }) perturbations of horizontal Laplacians in Carnot groups.
在 1981 年的开创性研究中,D.Jerison 在他 1981 年的开创性研究中展示了一个显著的负面现象,即在海森堡群 (mathbb {H}^{n}.) 的特征边界附近一般不存在肖德尔估计。从正面看,通过改编傅里叶分析和微局域分析的工具,他基于非各向同性的福兰-斯坦霍尔德类,在边界的非特征部分发展了肖德尔理论。另一方面,1976 年罗斯柴尔德和斯坦因关于其提升定理的著名研究确立了分层零potent Lie 群(现称为卡诺群)在赫曼德算子分析中的核心地位,但迄今为止,杰里逊的结果在这些亚黎曼环境中还没有已知的对应物。本文将填补这一空白。我们证明了最优的 (Gamma ^{k,α }) ((kge 2))Schauder estimates near a (C^{k,alpha }) non-characteristic portion of the boundary for (Gamma ^{k-2, alpha }) perturbations of horizontal Laplacians in Carnot groups.
{"title":"Higher order boundary Schauder estimates in Carnot groups","authors":"Agnid Banerjee, Nicola Garofalo, Isidro H. Munive","doi":"10.1007/s00208-024-02901-0","DOIUrl":"https://doi.org/10.1007/s00208-024-02901-0","url":null,"abstract":"<p>In his seminal 1981 study D. Jerison showed the remarkable negative phenomenon that there exist, in general, no Schauder estimates near the characteristic boundary in the Heisenberg group <span>(mathbb {H}^{n}.)</span> On the positive side, by adapting tools from Fourier and microlocal analysis, he developed a Schauder theory at a non-characteristic portion of the boundary, based on the non-isotropic Folland–Stein Hölder classes. On the other hand, the 1976 celebrated work of Rothschild and Stein on their lifting theorem established the central position of stratified nilpotent Lie groups (nowadays known as Carnot groups) in the analysis of Hörmander operators but, to present date, there exists no known counterpart of Jerison’s results in these sub-Riemannian ambients. In this paper we fill this gap. We prove optimal <span>(Gamma ^{k,alpha })</span> <span>((kge 2))</span> Schauder estimates near a <span>(C^{k,alpha })</span> non-characteristic portion of the boundary for <span>(Gamma ^{k-2, alpha })</span> perturbations of horizontal Laplacians in Carnot groups.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"95 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gromov’s (open) question whether the closed convex hull of finitely many points in a complete ({{,textrm{CAT},}}(0)) space is compact naturally extends to weaker notions of non-positive curvature in metric spaces. In this article, we consider metric spaces admitting a conical geodesic bicombing, and show that the question has a negative answer in this setting. Specifically, for each (n>1), we construct a complete metric space X admitting a conical geodesic bicombing, which is the closed convex hull of n points and is not compact. The space X moreover has the universal property that for any n points (A={x_1,ldots ,x_n}subset Y) in a complete ({{,textrm{CAT},}}(0)) space Y there exists a Lipschitz map (f:Xrightarrow Y) such that the convex hull of (A) is contained in f(X).
格罗莫夫提出了一个(开放的)问题:在一个完整的({,textrm{CAT},}(0))空间中,有限多个点的闭凸壳是否紧凑,这个问题自然延伸到了公元空间中较弱的非正曲率概念。在本文中,我们考虑了容许圆锥测地双梳理的度量空间,并证明了在这种情况下问题的答案是否定的。具体地说,对于每个 (n>1),我们构造了一个容许圆锥形大地双角的完整度量空间 X,它是 n 个点的闭凸壳,并且不紧凑。空间 X 还具有这样一个普遍性质:对于完整的 ({{,textrm{CAT},}}(0)) 空间 Y 中的任意 n 个点 (A={x_1,ldots ,x_n}subset Y) 都存在一个 Lipschitz 映射 (f:Xrightarrow Y) ,使得 (A) 的凸壳包含在 f(X) 中。
{"title":"A non-compact convex hull in generalized non-positive curvature","authors":"Giuliano Basso, Yannick Krifka, Elefterios Soultanis","doi":"10.1007/s00208-024-02905-w","DOIUrl":"https://doi.org/10.1007/s00208-024-02905-w","url":null,"abstract":"<p>Gromov’s (open) question whether the closed convex hull of finitely many points in a complete <span>({{,textrm{CAT},}}(0))</span> space is compact naturally extends to weaker notions of non-positive curvature in metric spaces. In this article, we consider metric spaces admitting a conical geodesic bicombing, and show that the question has a negative answer in this setting. Specifically, for each <span>(n>1)</span>, we construct a complete metric space <i>X</i> admitting a conical geodesic bicombing, which is the closed convex hull of <i>n</i> points and is not compact. The space <i>X</i> moreover has the universal property that for any <i>n</i> points <span>(A={x_1,ldots ,x_n}subset Y)</span> in a complete <span>({{,textrm{CAT},}}(0))</span> space <i>Y</i> there exists a Lipschitz map <span>(f:Xrightarrow Y)</span> such that the convex hull of <span>(A)</span> is contained in <i>f</i>(<i>X</i>).</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"87 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-30DOI: 10.1007/s00208-024-02899-5
R. İ. Nanç Baykur, Mustafa Korkmaz
We construct symplectic surface bundles over surfaces with positive signatures for all but 19 possible pairs of fiber and base genera. Meanwhile, we determine the commutator lengths of a few new mapping classes.
{"title":"Geography of surface bundles over surfaces","authors":"R. İ. Nanç Baykur, Mustafa Korkmaz","doi":"10.1007/s00208-024-02899-5","DOIUrl":"https://doi.org/10.1007/s00208-024-02899-5","url":null,"abstract":"<p>We construct symplectic surface bundles over surfaces with positive signatures for all but 19 possible pairs of fiber and base genera. Meanwhile, we determine the commutator lengths of a few new mapping classes.</p>","PeriodicalId":18304,"journal":{"name":"Mathematische Annalen","volume":"50 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}