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Mediterranean Journal of Mathematics最新文献

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On Density and Bishop–Phelps–Bollobás-Type Properties for the Minimum Norm 论最小规范的密度和毕晓普-菲尔普斯-波洛巴类型属性
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-08-02 DOI: 10.1007/s00009-024-02705-1
Domingo García, Manuel Maestre, Miguel Martín, Óscar Roldán
{"title":"On Density and Bishop–Phelps–Bollobás-Type Properties for the Minimum Norm","authors":"Domingo García, Manuel Maestre, Miguel Martín, Óscar Roldán","doi":"10.1007/s00009-024-02705-1","DOIUrl":"https://doi.org/10.1007/s00009-024-02705-1","url":null,"abstract":"<p>We study the set <span>({text {MA}}(X,Y))</span> of operators between Banach spaces <i>X</i> and <i>Y</i> that attain their minimum norm, and the set <span>({text {QMA}}(X,Y))</span> of operators that quasi attain their minimum norm. We characterize the Radon–Nikodym property in terms of operators that attain their minimum norm and obtain some related results about the density of the sets <span>({text {MA}}(X,Y))</span> and <span>({text {QMA}}(X,Y))</span>. We show that every infinite-dimensional Banach space <i>X</i> has an isomorphic space <i>Y</i>, such that not every operator from <i>X</i> to <i>Y</i> quasi attains its minimum norm. We introduce and study Bishop–Phelps–Bollobás type properties for the minimum norm, including the ones already considered in the literature, and we exhibit a wide variety of results and examples, as well as exploring the relations between them.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
Contact GRA Solitons and Applications to General Relativity 联系 GRA Solitons 和广义相对论的应用
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-24 DOI: 10.1007/s00009-024-02703-3
Sourav Nayak, Dhriti Sundar Patra
{"title":"Contact GRA Solitons and Applications to General Relativity","authors":"Sourav Nayak, Dhriti Sundar Patra","doi":"10.1007/s00009-024-02703-3","DOIUrl":"https://doi.org/10.1007/s00009-024-02703-3","url":null,"abstract":"<p>This article investigates generalized Ricci almost solitons, also known as GRA solitons, on contact metric manifolds, including the gradient case. At first, we establish that a complete <i>K</i>-contact or Sasakian manifold endowed with a closed GRA soliton satisfying <span>(4c_1c_2 ne 1)</span> is compact Einstein with scalar curvature <span>(2n(2n+1))</span>. As for the gradient case, it exhibits an isometry to the unit sphere <span>({mathbb {S}}^{2n+1})</span>. Subsequently, we identify a few adequate conditions under which a non-trivial complete <i>K</i>-contact manifold with a GRA soliton is trivial (<span>(eta )</span>-Einstein). Following that, we establish certain results on <i>H</i>-contact and complete contact manifolds. We also demonstrate that a non-Sasakian <span>((k,mu ))</span>-contact manifold with a closed GRA soliton is flat for dimension 3, and for higher dimensions, it is locally isometric to the trivial bundle <span>({mathbb {R}}^{n+1} times {mathbb {S}}^n(4))</span>, provided <span>(4c_1c_2 (1-2n)ne 1)</span> and <span>(c_2ne 0)</span>. Finally, we discuss a few applications of GRA solitons in general relativity. These include characterizing PF spacetimes with a concircular velocity vector field and determining a sufficient condition for a GRW spacetime to be a PF spacetime.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141771203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
Maximum-Norm a Posteriori Error Bounds for an Extrapolated Upwind Scheme Applied to a Singularly Perturbed Convection-Diffusion Problem 应用于奇异扰动对流扩散问题的外推上风方案的最大正态后验误差边界
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-19 DOI: 10.1007/s00009-024-02698-x
Torsten Linß, Goran Radojev
{"title":"Maximum-Norm a Posteriori Error Bounds for an Extrapolated Upwind Scheme Applied to a Singularly Perturbed Convection-Diffusion Problem","authors":"Torsten Linß, Goran Radojev","doi":"10.1007/s00009-024-02698-x","DOIUrl":"https://doi.org/10.1007/s00009-024-02698-x","url":null,"abstract":"<p>Richardson extrapolation is applied to a simple first-order upwind difference scheme for the approximation of solutions of singularly perturbed convection-diffusion problems in one dimension. Robust <i>a posteriori</i> error bounds are derived for the proposed method on arbitrary meshes. It is shown that the resulting error estimator can be used to steer an adaptive mesh algorithm that generates meshes resolving layers and singularities. Numerical results are presented that illustrate the theoretical findings.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141739016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
Solutions to a Pillai-Type Equation Involving Tribonacci Numbers and S-Units 涉及 Tribonacci 数和 S 单位的 Pillai 型方程的解法
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-17 DOI: 10.1007/s00009-024-02702-4
Herbert Batte, Florian Luca
{"title":"Solutions to a Pillai-Type Equation Involving Tribonacci Numbers and S-Units","authors":"Herbert Batte, Florian Luca","doi":"10.1007/s00009-024-02702-4","DOIUrl":"https://doi.org/10.1007/s00009-024-02702-4","url":null,"abstract":"<p>Let <span>( {T_n}_{nge 0} )</span> be the sequence of Tribonacci numbers. In this paper, we study the exponential Diophantine equation <span>(T_n-2^x3^y=c)</span>, for <span>(n,x,yin mathbb {Z}_{ge 0})</span>. In particular, we show that there is no integer <i>c</i> with at least six representations of the form <span>(T_n-2^x3^y)</span>.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141722268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
Vortex Ground State Solutions for Electromagnetostatic Schrödinger–Maxwell System with Critical Exponent 具有临界指数的静电薛定谔-麦克斯韦系统的涡旋基态解法
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-16 DOI: 10.1007/s00009-024-02701-5
Yuping Ji, Kaimin Teng
{"title":"Vortex Ground State Solutions for Electromagnetostatic Schrödinger–Maxwell System with Critical Exponent","authors":"Yuping Ji, Kaimin Teng","doi":"10.1007/s00009-024-02701-5","DOIUrl":"https://doi.org/10.1007/s00009-024-02701-5","url":null,"abstract":"","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141643031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
Solvability of a Family of Nonlinear Degenerate Parabolic Mixed Equations 非线性退化抛物混合方程组的可解性
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-16 DOI: 10.1007/s00009-024-02690-5
Ramiro Acevedo, Christian Gómez, Juan David Samboní
{"title":"Solvability of a Family of Nonlinear Degenerate Parabolic Mixed Equations","authors":"Ramiro Acevedo, Christian Gómez, Juan David Samboní","doi":"10.1007/s00009-024-02690-5","DOIUrl":"https://doi.org/10.1007/s00009-024-02690-5","url":null,"abstract":"","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141643756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 Property that Characterizes the Enneper Surface and Helix Surfaces 恩尼佩尔表面和螺旋面的一个特性
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-11 DOI: 10.1007/s00009-024-02697-y
Pascual Lucas, José Antonio Ortega-Yagües
{"title":"A Property that Characterizes the Enneper Surface and Helix Surfaces","authors":"Pascual Lucas, José Antonio Ortega-Yagües","doi":"10.1007/s00009-024-02697-y","DOIUrl":"https://doi.org/10.1007/s00009-024-02697-y","url":null,"abstract":"<p>The main goal of this paper is to show that helix surfaces and the Enneper surface are the only surfaces in the 3-dimensional Euclidean space <span>(mathbb {R}^{3})</span> whose isogonal lines are generalized helices and pseudo-geodesic lines.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
Weight Decompositions on Algebraic Models for Mapping Spaces and Homotopy Automorphisms 映射空间代数模型上的权重分解与同调自动形态
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-11 DOI: 10.1007/s00009-024-02700-6
Joana Cirici, Bashar Saleh
{"title":"Weight Decompositions on Algebraic Models for Mapping Spaces and Homotopy Automorphisms","authors":"Joana Cirici, Bashar Saleh","doi":"10.1007/s00009-024-02700-6","DOIUrl":"https://doi.org/10.1007/s00009-024-02700-6","url":null,"abstract":"<p>We obtain restrictions on the rational homotopy types of mapping spaces and of classifying spaces of homotopy automorphisms by means of the theory of positive weight decompositions. The theory applies, in particular, to connected components of holomorphic maps between compact Kähler manifolds as well as homotopy automorphisms of Kähler manifolds.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
LVM Manifolds and lck Metrics LVM 歧管和 lck 指标
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-09 DOI: 10.1007/s00009-024-02696-z
Bastien Faucard
{"title":"LVM Manifolds and lck Metrics","authors":"Bastien Faucard","doi":"10.1007/s00009-024-02696-z","DOIUrl":"https://doi.org/10.1007/s00009-024-02696-z","url":null,"abstract":"<p>In this paper, we compare two types of complex non-Kähler manifolds: LVM and lck manifolds. First, lck manifolds (for locally conformally Kähler manifolds) admit a metric which is locally conformal to a Kähler metric. On the other side, LVM manifolds (for López de Medrano, Verjovsky and Meersseman) are quotients of an open subset of <span>({mathbb {C}}^n)</span> by an action of <span>({mathbb {C}}^*times {mathbb {C}}^m)</span>. LVM and lck manifolds have a fundamental common point: Hopf manifolds which are a specific case of LVM manifolds and which admit also lck metric. Therefore, the question of this paper is:</p><blockquote><p>Are LVM manifolds lck ?</p></blockquote><p>We provide some answers to this question. The results obtained are as follows. In the set of all LVM manifolds, there is a dense subset of LVM manifolds which are not lck. And if we consider lck manifolds with potential (whose metric derives from a potential), the diagonal Hopf manifolds are the only LVM manifolds which admit an lck metric with potential. However, we show that there exists an lck covering with potential (non-compact) of a certain subclass of LVM manifolds. Finally, we present some examples.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
On the Inclusion Relations of Global Ultradifferentiable Classes Defined by Weight Matrices 论由权重矩阵定义的全局超微分类的包含关系
IF 1.1 3区 数学
Mediterranean Journal of Mathematics Pub Date : 2024-07-08 DOI: 10.1007/s00009-024-02694-1
Chiara Boiti, David Jornet, Alessandro Oliaro, Gerhard Schindl
{"title":"On the Inclusion Relations of Global Ultradifferentiable Classes Defined by Weight Matrices","authors":"Chiara Boiti, David Jornet, Alessandro Oliaro, Gerhard Schindl","doi":"10.1007/s00009-024-02694-1","DOIUrl":"https://doi.org/10.1007/s00009-024-02694-1","url":null,"abstract":"<p>We study and characterize the inclusion relations of global classes in the general weight matrix framework in terms of growth relations for the defining weight matrices. We consider the Roumieu and Beurling cases, and as a particular case, we also treat the classical weight function and weight sequence cases. Moreover, we construct a weight sequence which is oscillating around any weight sequence which satisfies some minimal conditions and, in particular, around the critical weight sequence <span>((p!)^{1/2})</span>, related with the non-triviality of the classes. Finally, we also obtain comparison results both on classes defined by weight functions that can be defined by weight sequences and conversely.</p>","PeriodicalId":49829,"journal":{"name":"Mediterranean Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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
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