scholarly journals Sharp Bounds for Fractional Conjugate Hardy Operator on Higher-Dimensional Product Spaces

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Zequn Wang ◽  
Mingquan Wei ◽  
Qianjun He ◽  
Dunyan Yan
Keyword(s):  
Operator Norm ◽  
Hardy Operator ◽  
Sharp Bound ◽  
Product Spaces ◽  
Sharp Bounds ◽  
Higher Dimensional

In this paper, we obtain the sharp bound for fractional conjugate Hardy operator on higher-dimensional product spaces from L1ℝn1×⋯×ℝnm to the space wLQℝn1×⋯×ℝnm and Lpℝn1×⋯×ℝnm to the space Lqℝn1×⋯×ℝnm. More generally, the operator norm of the fractional Hardy operator on higher-dimensional product spaces from LPℝn1×⋯×ℝnm to LQIℝn1×⋯×ℝnm is obtained.

The sharp bounds of the second and third Hankel determinants for the class 𝓢𝓛*

2020 ◽  
Vol 70 (4) ◽  
pp. 849-862
Author(s):  
Shagun Banga ◽  
S. Sivaprasad Kumar
Keyword(s):  
Triangle Inequality ◽  
Starlike Functions ◽  
Sharp Bound ◽  
The Novel ◽  
Sharp Bounds ◽  
Hankel Determinants ◽  
Lemniscate Of Bernoulli ◽  
Carathéodory Functions ◽  
The Right

AbstractIn this paper, we use the novel idea of incorporating the recently derived formula for the fourth coefficient of Carathéodory functions, in place of the routine triangle inequality to achieve the sharp bounds of the Hankel determinants H3(1) and H2(3) for the well known class 𝓢𝓛* of starlike functions associated with the right lemniscate of Bernoulli. Apart from that the sharp bound of the Zalcman functional: $\begin{array}{} |a_3^2-a_5| \end{array}$ for the class 𝓢𝓛* is also estimated. Further, a couple of interesting results of 𝓢𝓛* are also discussed.

scholarly journals A note on magnitude bounds for the mask coefficients of the interpolatory Dubuc–Deslauriers subdivision scheme

2014 ◽  
Vol 17 (1) ◽  
pp. 226-232
Author(s):  
H. E. Bez ◽  
N. Bez
Keyword(s):  
Recent Result ◽  
Operator Norm ◽  
Subdivision Scheme ◽  
Sharp Bounds

AbstractWe analyse the mask associated with the $2n$-point interpolatory Dubuc–Deslauriers subdivision scheme $S_{a^{[n]}}$. Sharp bounds are presented for the magnitude of the coefficients $a^{[n]}_{2i-1}$ of the mask. For scales $i \in [1,\sqrt{n}]$ it is shown that $|a^{[n]}_{2i-1}|$ is comparable to $i^{-1}$, and for larger power scales, exponentially decaying bounds are obtained. Using our bounds, we may precisely analyse the summability of the mask as a function of $n$ by identifying which coefficients of the mask contribute to the essential behaviour in $n$, recovering and refining the recent result of Deng–Hormann–Zhang that the operator norm of $S_{a^{[n]}}$ on $\ell ^\infty $ grows logarithmically in $n$.

scholarly journals Some inequalities for the norm and the numerical radius of linear operators in Hilbert spaces

2008 ◽  
Vol 39 (1) ◽  
pp. 1-7 ◽  
Author(s):  
S. S. Dragomir
Keyword(s):  
Hilbert Spaces ◽  
Linear Operators ◽  
Operator Norm ◽  
Inner Product ◽  
Product Spaces ◽  
Numerical Radius ◽  
Inner Product Spaces

In this paper various inequalities between the operator norm and its numerical radius are provided. For this purpose, we employ some classical inequalities for vectors in inner product spaces due to Buzano, Goldstein-Ryff-Clarke, Dragomir-S ´andor and the author.

Sharp bounds for Hardy operators on product spaces

2018 ◽  
Vol 38 (2) ◽  
pp. 441-449
Author(s):  
Mingquan WEI ◽  
Dunyan YAN
Keyword(s):  
Product Spaces ◽  
Sharp Bounds ◽  
Hardy Operators

scholarly journals On Lipschitz continuity with respect to the Poincaré metric of linear contractions between Möbius gyrovector spaces

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Keiichi Watanabe
Keyword(s):  
Linear Operator ◽  
Lipschitz Continuity ◽  
Lipschitz Constant ◽  
Operator Norm ◽  
Inner Product ◽  
Product Spaces ◽  
Poincaré Metric ◽  
Lipschitz Continuous ◽  
Inner Product Spaces

AbstractFor every linear operator between inner product spaces whose operator norm is less than or equal to one, we show that the restriction to the Möbius gyrovector space is Lipschitz continuous with respect to the Poincaré metric. Moreover, the Lipschitz constant is precisely the operator norm.

scholarly journals Castelnuovo bounds for higher-dimensional varieties

2012 ◽  
Vol 148 (4) ◽  
pp. 1085-1132 ◽  
Author(s):  
F. L. Zak
Keyword(s):  
Betti Numbers ◽  
Higher Dimension ◽  
Algebraic Varieties ◽  
Sectional Genus ◽  
Sharp Bounds ◽  
Higher Dimensional ◽  
Dual Varieties ◽  
Hyperplane Sections

AbstractWe give bounds for the Betti numbers of projective algebraic varieties in terms of their classes (degrees of dual varieties of successive hyperplane sections). We also give bounds for classes in terms of ramification volumes (mixed ramification degrees), sectional genus and, eventually, in terms of dimension, codimension and degree. For varieties whose degree is large with respect to codimension, we give sharp bounds for the above invariants and classify the varieties on the boundary, thus obtaining a generalization of Castelnuovo’s theory for curves to varieties of higher dimension.

scholarly journals A Sharp Bound for the Product of Weights of Cross-Intersecting Families

10.37236/5782 ◽  
2016 ◽  
Vol 23 (4) ◽  
Author(s):  
Peter Borg
Keyword(s):  
General Setting ◽  
Sharp Bound ◽  
Integer Sequences ◽  
Sharp Bounds ◽  
The Family ◽  
Intersecting Families

Two families $\mathcal{A}$ and $\mathcal{B}$ of sets are said to be cross-intersecting if each set in $\mathcal{A}$ intersects each set in $\mathcal{B}$. For any two integers $n$ and $k$ with $1 \leq k \leq n$, let ${[n] \choose \leq k}$ denote the family of subsets of $\{1, \dots, n\}$ of size at most $k$, and let $\mathcal{S}_{n,k}$ denote the family of sets in ${[n] \choose \leq k}$ that contain $1$. The author recently showed that if $\mathcal{A} \subseteq {[m] \choose \leq r}$, $\mathcal{B} \subseteq {[n] \choose \leq s}$, and $\mathcal{A}$ and $\mathcal{B}$ are cross-intersecting, then $|\mathcal{A}||\mathcal{B}| \leq \mathcal{S}_{m,r}||\mathcal{S}_{n,s}|$. We prove a version of this result for the more general setting of \emph{weighted} sets. We show that if $g : {[m] \choose \leq r} \rightarrow \mathbb{R}^+$ and $h : {[n] \choose \leq s} \rightarrow \mathbb{R}^+$ are functions that obey certain conditions, $\mathcal{A} \subseteq {[m] \choose \leq r}$, $\mathcal{B} \subseteq {[n] \choose \leq s}$, and $\mathcal{A}$ and $\mathcal{B}$ are cross-intersecting, then $$\sum_{A \in \mathcal{A}} g(A) \sum_{B \in \mathcal{B}} h(B) \leq \sum_{C \in \mathcal{S}_{m,r}} g(C) \sum_{D \in \mathcal{S}_{n,s}} h(D).$$The bound is attained by taking $\mathcal{A} = \mathcal{S}_{m,r}$ and $\mathcal{B} = \mathcal{S}_{n,s}$. We also show that this result yields new sharp bounds for the product of sizes of cross-intersecting families of integer sequences and of cross-intersecting families of multisets.

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