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Positivity最新文献

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Inequalities of singular values and unitarily invariant norms for sums and products of matrices 奇异值不等式和矩阵和积的单位不变规范
IF 1 3区 数学
Positivity Pub Date : 2024-05-03 DOI: 10.1007/s11117-024-01053-4
Jianguo Zhao
{"title":"Inequalities of singular values and unitarily invariant norms for sums and products of matrices","authors":"Jianguo Zhao","doi":"10.1007/s11117-024-01053-4","DOIUrl":"https://doi.org/10.1007/s11117-024-01053-4","url":null,"abstract":"<p>In this work, we investigate inequalities of singular values and unitarily invariant norms for sums and products of matrices. First, we prove that <span>(s^{2}big (XY^{*}big )prec _{wlog }sbig ((X^{*}X)^{q}(Y^{*}Y)(X^{*}X)^{1-q}big ))</span>, where <span>(X, Yin M_{n}(C))</span> and <span>(0&lt;q&lt;1)</span>. Based on this result, we present some inequalities between sum of the <i>t</i>-geometric mean and sum of the product of matrices. Those obtained results are the generalization of the present results. In the end, we present a singular values version of Audenaert’s inequality [1].</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"17 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885953","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
z-congruences and topologies on $$C^+(X)$$ $$C^+(X)$$上的z共轭和拓扑结构
IF 1 3区 数学
Positivity Pub Date : 2024-04-28 DOI: 10.1007/s11117-024-01049-0
Pronay Biswas, Sagarmoy Bag, Sujit Kumar Sardar
{"title":"z-congruences and topologies on $$C^+(X)$$","authors":"Pronay Biswas, Sagarmoy Bag, Sujit Kumar Sardar","doi":"10.1007/s11117-024-01049-0","DOIUrl":"https://doi.org/10.1007/s11117-024-01049-0","url":null,"abstract":"<p>For a Tychonoff space <i>X</i>, <span>(C^+(X))</span> denotes the non-negative real-valued continuous functions on <i>X</i>. We obtain a correlation between <i>z</i>-congruences on the ring <i>C</i>(<i>X</i>) and <i>z</i>-congruences on the semiring <span>(C^+(X))</span>. We give a new characterization of P-spaces via <i>z</i>-congruences on <span>(C^+(X))</span>. The <i>z</i>-congruences on <span>(C^+(X))</span> are shown to have an algebraic nature like <i>z</i>-ideals. We study some topological properties of <span>(C^+(X))</span> under <i>u</i>-topology and <i>m</i>-topology. It is shown that a proper ideal of <span>(C^+(X))</span> is closed under <i>m</i>-topology if and only if it is the intersection of maximal ideals of <span>(C^+(X))</span>. Also, we prove that every ideal of <span>(C^+(X))</span> is closed if and only if <i>X</i> is a <i>P</i>-space. We investigate the connectedness and compactness of <span>(C^+(X))</span> under <i>m</i>-topology. It is shown that the component of <span>(varvec{0})</span> is <span>(C_psi (X)cap C^+(X))</span>. Finally, we show that <span>(C_m^+(X))</span> is locally compact, <span>(sigma )</span>-compact and hemicompact if and only if <i>X</i> is finite.</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"77 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140812316","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
The monotonicity of Orlicz–Lorentz spaces equipped with the F-norm 配备 F 准则的奥利兹-洛伦兹空间的单调性
IF 1 3区 数学
Positivity Pub Date : 2024-04-27 DOI: 10.1007/s11117-024-01048-1
Yangyang Xue, Yunan Cui
{"title":"The monotonicity of Orlicz–Lorentz spaces equipped with the F-norm","authors":"Yangyang Xue, Yunan Cui","doi":"10.1007/s11117-024-01048-1","DOIUrl":"https://doi.org/10.1007/s11117-024-01048-1","url":null,"abstract":"<p>In this paper, we introduce a new F-normed space, namely Orlicz–Lorentz spaces equipped with the Mazur–Orlicz F-norm. Some basic properties in Orlicz–Lorentz spaces equipped with the Mazur–Orlicz F-norm are given. We find a tool to study the geometry property of Orlicz–Lorentz function spaces, the necessary and sufficient conditions for strict monotonicity, lower local uniform monotonicity, upper local uniform monotonicity in Orlicz–Lorentz spaces endowed with the Mazur–Orlicz F-norm are obtained without any assumptions. The tool also can simplify the proof of the corresponding results of Orlicz–Lorentz spaces equipped with the Luxemburg norm without condition (+).</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"20 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140812918","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
Weak integrability of operator valued functions with values in ideals of compact operators on Hilbert space 在希尔伯特空间上紧凑算子的理想中取值的算子值函数的弱可积分性
IF 1 3区 数学
Positivity Pub Date : 2024-04-13 DOI: 10.1007/s11117-024-01047-2
Matija Milović
{"title":"Weak integrability of operator valued functions with values in ideals of compact operators on Hilbert space","authors":"Matija Milović","doi":"10.1007/s11117-024-01047-2","DOIUrl":"https://doi.org/10.1007/s11117-024-01047-2","url":null,"abstract":"<p>In this paper, we provide some sufficient conditions for Pettis integrability of operator valued functions that take values in ideals of compact operators on the separable Hilbert space. Additionally, we show that, in general, these conditions do not imply Bochner integrability.</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"25 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140580408","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
Kernel embedding of measures and low-rank approximation of integral operators 度量的核嵌入和积分算子的低阶逼近
IF 1 3区 数学
Positivity Pub Date : 2024-04-04 DOI: 10.1007/s11117-024-01041-8
Bertrand Gauthier
{"title":"Kernel embedding of measures and low-rank approximation of integral operators","authors":"Bertrand Gauthier","doi":"10.1007/s11117-024-01041-8","DOIUrl":"https://doi.org/10.1007/s11117-024-01041-8","url":null,"abstract":"<p>We describe a natural coisometry from the Hilbert space of all Hilbert-Schmidt operators on a separable reproducing kernel Hilbert space <span>(hbox { (RKHS)}, mathcal {H})</span> and onto the RKHS <span>(mathcal {G})</span> associated with the squared-modulus of the reproducing kernel of <span>(mathcal {H})</span>. Through this coisometry, trace-class integral operators defined by general measures and the reproducing kernel of <span>(mathcal {H})</span> are isometrically represented as potentials in <span>(mathcal {G})</span>, and the quadrature approximation of these operators is equivalent to the approximation of integral functionals on <span>(mathcal {G})</span>. We then discuss the extent to which the approximation of potentials in RKHSs with squared-modulus kernels can be regarded as a differentiable surrogate for the characterisation of low-rank approximation of integral operators.</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"280 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140580400","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 $$varepsilon $$ -quasi efficient solutions for fractional infinite multiobjective optimization problems with locally Lipschitz data 关于具有局部 Lipschitz 数据的分数无限多目标优化问题的 $$varepsilon $$ 准高效解决方案
IF 1 3区 数学
Positivity Pub Date : 2024-04-01 DOI: 10.1007/s11117-024-01046-3
Thanh-Hung Pham
{"title":"On $$varepsilon $$ -quasi efficient solutions for fractional infinite multiobjective optimization problems with locally Lipschitz data","authors":"Thanh-Hung Pham","doi":"10.1007/s11117-024-01046-3","DOIUrl":"https://doi.org/10.1007/s11117-024-01046-3","url":null,"abstract":"<p>In this paper, we investigate optimality conditions and duality for <span>(varepsilon )</span>-quasi efficient solutions of the fractional infinite multiobjective optimization problems with locally Lipschitz data. The obtained results improve or include some recent known ones. Several illustrative examples are also provided.</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"2015 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140580398","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
Estimates related to the iterates of positive linear operators and their multidimensional analogues 与正线性算子迭代相关的估计值及其多维类似物
IF 1 3区 数学
Positivity Pub Date : 2024-03-22 DOI: 10.1007/s11117-024-01045-4
Octavian Agratini, Radu Precup
{"title":"Estimates related to the iterates of positive linear operators and their multidimensional analogues","authors":"Octavian Agratini, Radu Precup","doi":"10.1007/s11117-024-01045-4","DOIUrl":"https://doi.org/10.1007/s11117-024-01045-4","url":null,"abstract":"<p>The starting point of this paper is the construction of a general family <span>( (L_{n})_{nge 1})</span> of positive linear operators of discrete type. Considering <span>((L_{n}^{k})_{kge 1})</span> the sequence of iterates of one of such operators, <span>(L_{n})</span>, our goal is to find an expression of the upper edge of the error <span>(Vert L_{n}^{k}f-f^{*}Vert )</span>, <span>(fin C[0,1])</span>, where <span>(f^{*} )</span> is the fixed point of <span>(L_{n}.)</span> The estimate makes use of the error formula for the sequence of successive approximations in Banach’s fixed point theorem and the error of approximation of the operator <span>(L_{n}.)</span> Examples of special operators are inserted. Some extensions to multidimensional approximation operators are also given.\u0000</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"7 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140201935","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
Short note on some geometric inequalities derived from matrix inequalities 关于从矩阵不等式推导出的一些几何不等式的简短说明
IF 1 3区 数学
Positivity Pub Date : 2024-03-20 DOI: 10.1007/s11117-024-01042-7
{"title":"Short note on some geometric inequalities derived from matrix inequalities","authors":"","doi":"10.1007/s11117-024-01042-7","DOIUrl":"https://doi.org/10.1007/s11117-024-01042-7","url":null,"abstract":"<h3>Abstract</h3> <p>Using the connection between ellipsoids and positive semidefinite matrices we provide alternative proofs to some recently proven inequalities concerning the volume of <span> <span>(L_2)</span> </span> zonoids as consequences of classical inequalities for matrices.</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"32 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140168675","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
Discrete stopping times in the lattice of continuous functions 连续函数网格中的离散停止时间
IF 1 3区 数学
Positivity Pub Date : 2024-03-19 DOI: 10.1007/s11117-024-01044-5
Achintya Raya Polavarapu
{"title":"Discrete stopping times in the lattice of continuous functions","authors":"Achintya Raya Polavarapu","doi":"10.1007/s11117-024-01044-5","DOIUrl":"https://doi.org/10.1007/s11117-024-01044-5","url":null,"abstract":"<p>A functional calculus for an order complete vector lattice <span>({mathcal {E}})</span> was developed by Grobler (Indag Math (NS) 25(2):275–295, 2014) using the Daniell integral. We show that if one represents the universal completion of <span>({mathcal {E}})</span> as <span>(C^infty (K))</span>, where <i>K</i> is an extremally disconnected compact Hausdorff topological space, then the Daniell functional calculus for continuous functions is exactly the pointwise composition of functions in <span>(C^infty (K))</span>. This representation allows an easy deduction of the various properties of the functional calculus. Afterwards, we study discrete stopping times and stopped processes in <span>(C^infty (K))</span>. We obtain a representation that is analogous to what is expected in probability theory.\u0000</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"26 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140168487","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
Lebesgue spaces with variable exponent: some applications to the Navier–Stokes equations 具有可变指数的勒贝格空间：纳维耶-斯托克斯方程的一些应用
IF 1 3区 数学
Positivity Pub Date : 2024-03-18 DOI: 10.1007/s11117-024-01043-6
Diego Chamorro, Gastón Vergara-Hermosilla
{"title":"Lebesgue spaces with variable exponent: some applications to the Navier–Stokes equations","authors":"Diego Chamorro, Gastón Vergara-Hermosilla","doi":"10.1007/s11117-024-01043-6","DOIUrl":"https://doi.org/10.1007/s11117-024-01043-6","url":null,"abstract":"<p>In this article we study some problems related to the incompressible 3D Navier–Stokes equations from the point of view of Lebesgue spaces of variable exponent. These functional spaces present some particularities that make them quite different from the usual Lebesgue spaces: indeed, some of the most classical tools in analysis are not available in this framework. We will give here some ideas to overcome some of the difficulties that arise in this context in order to obtain different results related to the existence of mild solutions for this evolution problem.</p>","PeriodicalId":54596,"journal":{"name":"Positivity","volume":"61 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140152155","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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