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Sharps Bounds for Power Mean in Terms of Contraharmonic Mean
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作者 Zeid I. Almuhiameed 《Journal of Applied Mathematics and Physics》 2020年第7期1229-1235,共7页
In this research work, we consider the below inequalities: (1.1). The researchers attempt to find an answer as to what are the best possible parameters <i><i>&#945;</i></i>, <i><i&... In this research work, we consider the below inequalities: (1.1). The researchers attempt to find an answer as to what are the best possible parameters <i><i>&#945;</i></i>, <i><i>&#946;</i></i> that (1.1) can be held? The main tool is the optimization of some suitable functions that we seek to find out. Without loss of generality, we have assumed that <i>a</i> > <i>b</i> and let <img src="Edit_26c0f99b-93dd-48ff-acdb-f1c8047744f1.bmp" alt="" /> for 1) and <i>a</i> < <i>b</i>, <img src="Edit_15c32a7a-e9ae-41d3-8f49-c6b9c01c7ece.bmp" alt="" />(<i>t</i> small) for 2) to determine the condition for <i><i>&#945;</i></i> and <i><i>&#946;</i></i> to become <i>f</i>(<i>t</i>) ≤ 0 and <i>g</i>(<i>t</i>) ≥ 0. 展开更多
关键词 sharps bounds Power Mean Contraharmonic Mean
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A SHARP ESTIMATE ON THE DEGREE OF APPROXIMATION TO FUNCTIONS OF BOUNDED VARIATION BY CERTAIN OPERATORS 被引量:1
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作者 Vijay Gupta 《Analysis in Theory and Applications》 1995年第3期106-107,共2页
Recently Guo introduced integrated Meyer -Konig and Zeller operators and studied the rate of convergence for function of bounded variation. In this note we give a sharp estimate for these operators.
关键词 A sharp ESTIMATE ON THE DEGREE OF APPROXIMATION TO FUNCTIONS OF BOUNDED VARIATION BY CERTAIN OPERATORS
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On a special type of Ma-Minda function
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作者 S.Sivaprasad Kumar Shagun Banga 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2024年第4期654-673,共20页
We introduce a primitive class of analytic functions, by specializing in many wellknown classes, classify Ma-Minda functions based on its conditions and their interesting geometrical aspects. Further, study a newly de... We introduce a primitive class of analytic functions, by specializing in many wellknown classes, classify Ma-Minda functions based on its conditions and their interesting geometrical aspects. Further, study a newly defined subclass of starlike functions involving a special type of Ma-Minda function introduced here for obtaining inclusion and radius results. We also establish some majorization, Bloch function norms, and other related problems for the same class. 展开更多
关键词 Ma-Minda function typically real function Hankel determinants sharp coefficient bounds radius problems logarithmic function
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Sharp Growth Theorems and Coefficient Bounds for Starlike Mappings in Several Complex Variables 被引量:29
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作者 Hidetaka HAMADA Tatsuhiro HONDA 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2008年第4期353-368,共16页
Let B be the unit ball in a complex Banach space. Let S^*k+1(B) be the family of normalized starlike mappings f on B such that z = 0 is a zero of order k + 1 of f(z) - z. The authors obtain sharp growth and cov... Let B be the unit ball in a complex Banach space. Let S^*k+1(B) be the family of normalized starlike mappings f on B such that z = 0 is a zero of order k + 1 of f(z) - z. The authors obtain sharp growth and covering theorems, as well as sharp coefficient bounds for various subsets of S^*k+1(B). 展开更多
关键词 sharp coefficient bound sharp covering theorem sharp growth theorem Starlike mapping Zero of order k
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Sharp weak bounds for n-dimensional fractional Hardy operators 被引量:1
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作者 Haixia YU Junfeng LI 《Frontiers of Mathematics in China》 SCIE CSCD 2018年第2期449-457,共9页
We obtain the operator norms of the n-dimensional fractional Hardy operator Hα(0 〈 α 〈 n) from weighted Lebesgue spaces Lp|x|p(R^n) to weighted weak Lebesgue spacesLq,∞|x|β(R^n).
关键词 sharp weak bound fractional Hardy operator Lebesgue space with power weight
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ON REFINEMENT OF THE COEFFICIENT INEQUALITIES FOR A SUBCLASS OF QUASI-CONVEX MAPPINGS IN SEVERAL COMPLEX VARIABLES
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作者 Qinghua XU Yuanping LAI 《Acta Mathematica Scientia》 SCIE CSCD 2020年第6期1653-1665,共13页
Let K be the familiar class of normalized convex functions in the unit disk.In[14],Keogh and Merkes proved that for a function f(z)=z+∑k=2∞a k z k in the class K,|a 3−λa 22|≤max{13,|λ−1|},λ∈C.The above estimate... Let K be the familiar class of normalized convex functions in the unit disk.In[14],Keogh and Merkes proved that for a function f(z)=z+∑k=2∞a k z k in the class K,|a 3−λa 22|≤max{13,|λ−1|},λ∈C.The above estimate is sharp for eachλ.In this article,we establish the corresponding inequality for a normalized convex function f on U such that z=0 is a zero of order k+1 of f(z)−z,and then we extend this result to higher dimensions.These results generalize some known results. 展开更多
关键词 Fekete-Szegö problem subclass of quasi-convex mappings sharp coefficient bound
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On the Coefficient Inequality for A Subclass of Starlike Mappings in Several Complex Variables
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作者 GUO Sheng-ti XU Qing-hua 《Chinese Quarterly Journal of Mathematics》 2018年第1期98-110,共13页
Let S~* be the familiar class of normalized univalent functions in the unit disk.In [9], Keogh and Merkes proved that for a function f(z) = z +∑k=2∞ a_kz^k in the class S~*,then |a_3-λa_2~2| ≤ max{1, |3-4λ|}, λ... Let S~* be the familiar class of normalized univalent functions in the unit disk.In [9], Keogh and Merkes proved that for a function f(z) = z +∑k=2∞ a_kz^k in the class S~*,then |a_3-λa_2~2| ≤ max{1, |3-4λ|}, λ∈ C. In this article, we investigate the corresponding problem for the subclass of starlike mappings defined on the unit ball in a complex Banach space, on the unit polydisk in Cnand the bounded starlike circular domain in C~■, respectively. 展开更多
关键词 Fekete-Szego problem Subclass of starlike mappings sharp coefficient bound
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Escobar’s Conjecture on a Sharp Lower Bound for the First Nonzero Steklov Eigenvalue
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作者 Chao Xia Changwei Xiong 《Peking Mathematical Journal》 CSCD 2024年第2期759-778,共20页
It was conjectured by Escobar(J Funct Anal 165:101–116,1999)that for an ndimensional(n≥3)smooth compact Riemannian manifold with boundary,which has nonnegative Ricci curvature and boundary principal curvatures bound... It was conjectured by Escobar(J Funct Anal 165:101–116,1999)that for an ndimensional(n≥3)smooth compact Riemannian manifold with boundary,which has nonnegative Ricci curvature and boundary principal curvatures bounded below by c>0,the first nonzero Steklov eigenvalue is greater than or equal to c with equality holding only on isometrically Euclidean balls with radius 1/c.In this paper,we confirm this conjecture in the case of nonnegative sectional curvature.The proof is based on a combination of Qiu-Xia’s weighted Reilly-type formula with a special choice of the weight function depending on the distance function to the boundary,as well as a generalized Pohozaev-type identity. 展开更多
关键词 Stekloveigenvalue Laplacian eigenvalue sharp bound Nonnegative sectional curvature
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Sharp Bound for the Generalized m-Linear n-Dimensional Hardy-Littlewood-Polya Operator
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作者 Qianjun He Mingquan Wei Dunyan Yan 《Analysis in Theory and Applications》 CSCD 2023年第1期28-41,共14页
In this paper,we calculate the sharp bound for the generalized m-linear n-dimensional Hardy-Littlewood-Polya operator on power weighted central and non-central homogeneous Morrey spaces.As an application,the sharp bou... In this paper,we calculate the sharp bound for the generalized m-linear n-dimensional Hardy-Littlewood-Polya operator on power weighted central and non-central homogeneous Morrey spaces.As an application,the sharp bound for the Hardy-Littlewood-Polya operator on power weighted central and noncentral homo-geneous Morrey spaces is obtained.Finally,we also find the sharp bound for the Hausdorff operator on power weighted central and noncentral homogeneous Morrey spaces,which generalizes the previous results. 展开更多
关键词 sharp bound n-dimensional Hardy-Littlewood-Polya operator power weight Morrey space Hausdorff operator
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Multilinear Hausdorff Operators and Their Best Constants 被引量:12
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作者 Jie Cheng CHEN Da Shan FAN Chun Jie ZHANG 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2012年第8期1521-1530,共10页
In this paper, we study two different extensions of the Hausdorff operator to the multilinear case. Boundedness on Lebesgue spaces and Herz spaces is obtained. The bound on the Lebesgue space is optimal. Our results a... In this paper, we study two different extensions of the Hausdorff operator to the multilinear case. Boundedness on Lebesgue spaces and Herz spaces is obtained. The bound on the Lebesgue space is optimal. Our results are substantial extensions of some known results on Multilinear high dimensional Hardy operator. 展开更多
关键词 Hausdorff operator MULTILINEAR Herz space sharp bounds
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Spectral Gap of the Largest Eigenvalue of the Normalized Graph Laplacian
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作者 Jürgen Jost Raffaella Mulas Florentin Münch 《Communications in Mathematics and Statistics》 SCIE 2022年第3期371-381,共11页
We offer a new method for proving that the maxima eigenvalue of the normalized graph Laplacian of a graph with n vertices is at least n+1/n−1 provided the graph is not complete and that equality is attained if and onl... We offer a new method for proving that the maxima eigenvalue of the normalized graph Laplacian of a graph with n vertices is at least n+1/n−1 provided the graph is not complete and that equality is attained if and only if the complement graph is a single edge or a complete bipartite graph with both parts of size n−1/2.With the same method,we also prove a new lower bound to the largest eigenvalue in terms of the minimum vertex degree,provided this is at most n−1/2. 展开更多
关键词 Spectral graph theory Normalized Laplacian Largest eigenvalue sharp bounds
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Endpoint estimates for n-dimensional Hardy operators and their commutators 被引量:21
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作者 ZHAO FaYou FU ZunWei LU ShanZhen 《Science China Mathematics》 SCIE 2012年第10期1977-1990,共14页
In this paper,the sharp bound for the weak-type(1,1) inequality for the n-dimensional Hardy operator is obtained.Moreover,the precise norms of generalized Hardy operators on the type of Campanato spaces are worked out... In this paper,the sharp bound for the weak-type(1,1) inequality for the n-dimensional Hardy operator is obtained.Moreover,the precise norms of generalized Hardy operators on the type of Campanato spaces are worked out.As applications,the corresponding norms of the Riemann-Liouville integral operator and the n-dimensional Hardy operator are deduced.It is also proved that the n-dimensional Hardy operator maps from the Hardy space into the Lebesgue space.The endpoint estimate for the commutator generated by the Hardy operator and the(central) BMO function is also discussed. 展开更多
关键词 sharp bound generalized Hardy operator COMMUTATOR Campanato space Hardy space
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Fekete and Szeg problem in one and higher dimensions 被引量:4
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作者 Qinghua Xu Taishun Liu Xiaosong Liu 《Science China Mathematics》 SCIE CSCD 2018年第10期1775-1788,共14页
In this paper, we establish the Fekete and Szego inequality for a class of holomorphic functions in the unit disk, and then we extend this result to a class of holomorphic mappings on the unit ball in a complex Banach... In this paper, we establish the Fekete and Szego inequality for a class of holomorphic functions in the unit disk, and then we extend this result to a class of holomorphic mappings on the unit ball in a complex Banach space or on the unit polydisk in Cn. 展开更多
关键词 Fekete and Szego problem Bieberbach conjectures in several complex variables subclasses ofstarlike mappings sharp coefficient bound
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On the Fekete and Szego Problem for Starlike Mappings of Order α 被引量:3
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作者 Qing Hua XU Fang FANG Tai Shun LIU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2017年第4期554-564,共11页
Let Sα*be the familiar class of normalized starlike functions of order α in the unit disk. In this paper, we establish the Fekete and Szeg? inequality for the class Sα*, and then we generalize this result to the un... Let Sα*be the familiar class of normalized starlike functions of order α in the unit disk. In this paper, we establish the Fekete and Szeg? inequality for the class Sα*, and then we generalize this result to the unit ball in a complex Banach space or on the unit polydisk in Cn. 展开更多
关键词 Fekete–Szego problem starlike mappings of order α sharp coefficient bound
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