On One Generalization of the Hardy–Littlewood–Pólya Inequality

We generalize the Hardy–Littlewood–Pólya inequality for numerical sets to certain sets of vectors on a plane.     

Hardy–Littlewood–Polya’s Inequality and a New Concept of Weak Majorization

In this paper, we study some weak majorization properties with applications for the trees. A strongly notion of majorization is introduced and Hardy–Littlewood–Polya’s inequality is generalized.     

Lower Bounds for the Wiener Norm in ℤpd

Mathematical Notes - We obtain lower bounds for the ℓ1-norm of the Fourier transform of functions on ℤpd.     

Upper and Lower Bounds for Probabilities in the Conditional Borel–Cantelli Lemma

We obtain an inequality connected with a conditional version of the generalized Borel–Cantelli lemma.     

On Fast Polynomial Algorithms and Lower Bounds of the Linear Complexity

ＯｎＦａｓｔＰｏｌｙｎｏｍｉａｌＡｌｇｏｒｉｔｈｍｓａｎｄＬｏｗｅｒＢｏｕｎｄｓｏｆｔｈｅＬｉｎｅａｒＣｏｍｐｌｅｘｉｔｙＬｉＬｅｉ（李磊）（Ｘｉ＇ａｎＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ，Ｘｉ＇ａｎ，Ｃｈｉｎａ，＆ＡｏｍｏｒｉＵｎｉｖｅｒｓｉｔｙ，...     

Improved Hardy–Littlewood–Sobolev Inequality on Sn under Constraints

In this paper, we establish an improved Hardy–Littlewood–Sobolev inequality on Snunder higher-order moments constraint. Moreover, by constructing precise test functions, using improved Hardy–Littlewood–Sobolev inequality on Sn, we show such inequality is almost optimal in critical case.As an application, we give a simpler proof of the existence of the maximizer for conformal Hardy–Littlewood–Sobolev inequality.     

Optimal Bounds on the Modulus of Continuity of the Uncentered Hardy–Littlewood Maximal Function

We obtain sharp bounds for the modulus of continuity of the uncentered maximal function in terms of the modulus of continuity of the given function, via integral formulas. Some of the results deduced from these formulas are the following: The best constants for Lipschitz and Hölder functions on proper subintervals of ? are Lip? _α (Mf)≤(1+α)^?1Lip? _α (f), α∈(0,1]. On ?, the best bound for Lipschitz functions is \(\operatorname{Lip} ( Mf) \le (\sqrt{2} -1)\operatorname{Lip}( f)\). In higher dimensions, we determine the asymptotic behavior, as d→∞, of the norm of the maximal operator associated with cross-polytopes, Euclidean balls, and cubes, that is, ? _p balls for p=1,2,∞. We do this for arbitrary moduli of continuity. In the specific case of Lipschitz and Hölder functions, the operator norm of the maximal operator is uniformly bounded by 2^?α/q , where q is the conjugate exponent of p=1,2, and as d→∞ the norms approach this bound. When p=∞, best constants are the same as when p=1.     

Asymptotic approximations to the Hardy–Littlewood function

The function Q(x):=_∑n≥1(1/n)sin(x/n)$Q\left(x\right):={\sum }_{n\ge 1}(1/n)sin(x/n)$ was introduced by Hardy and Littlewood (1936) [5] in their study of Lambert summability, and since then it has attracted attention of many researchers. In particular, this function has made a surprising appearance in the recent disproof by Alzer, Berg and Koumandos (2005) [3] of a conjecture by Clark and Ismail (2003) [14]. More precisely, Alzer et al. have shown that the Clark and Ismail conjecture is true if and only if Q(x)≥−π/2$Q\left(x\right)\ge -\pi /2$ for all x>0$x>0$. It is known that Q(x)$Q\left(x\right)$ is unbounded in the domain x∈(0,∞)$x\in (0,\infty )$ from above and below, which disproves the Clark and Ismail conjecture, and at the same time raises a natural question of whether we can exhibit at least one point x$x$ for which Q(x)<−π/2$Q\left(x\right)<-\pi /2$. This turns out to be a surprisingly hard problem, which leads to an interesting and non-trivial question of how to approximate Q(x)$Q\left(x\right)$ for very large values of x$x$. In this paper we continue the work started by Gautschi (2005) in [4] and develop several approximations to Q(x)$Q\left(x\right)$ for large values of x$x$. We use these approximations to find an explicit value of x$x$ for which Q(x)<−π/2$Q\left(x\right)<-\pi /2$.     

Hardy–Littlewood–Sobolev inequality on the parabolic biangle

The Ramanujan Journal - We define the heat semigroup associated with a system of bivariate Jacobi polynomials which are orthogonal with respect to a probability measure on the parabolic biangle...     

A metric discrepancy result for the Hardy–Littlewood–Pólya sequences

The exact law of the iterated logarithm for discrepancies of the Hardy– Littlewood–Pólya sequences is proved. The exact constant in the law of the iterated logarithm is explicitly computed in the case when the Hardy–Littlewood–Pólya sequence consists of odd numbers.     

Hardy–Littlewoodʼs inequalities in the case of a capacity

Hardy–Littlewood?s inequalities, well known in the case of a probability measure, are extended to the case of a monotone (but not necessarily additive) set function, called a capacity. The upper inequality is established in the case of a capacity assumed to be continuous and submodular, the lower — under assumptions of continuity and supermodularity.     

A Hardy–Trudinger–Moser Inequality Involving LpNorm in the Hyperbolic Space

Let B be the unit disc in R~2, H be the completion of C_0∞(B) under the norm■ .By the method of blow-up analysis and an argument of rearrangement with respect to the standard hyperbolic metric ■, we prove that, for any fixed■ ,the supremum■ .This is an analog of early results of Lu–Yang(Discrete Contin. Dyn. Syst., 2009) and Yang(Trans.Amer. Math. Soc., 2007), and extends those of Wang–Ye(Adv. Math., 2012) and Yang–Zhu(Ann.Global Anal. Geom., 2016).     

Bounds of Singular Integrals on Weighted Hardy Spaces and Discrete Littlewood–Paley Analysis

We apply the discrete version of Calderón??s reproducing formula and Littlewood?CPaley theory with weights to establish the $H^{p}_{w} \to H^{p}_{w}$ (0<p<??) and $H^{p}_{w}\to L^{p}_{w}$ (0<p??1) boundedness for singular integral operators and derive some explicit bounds for the operator norms of singular integrals acting on these weighted Hardy spaces when we only assume w??A _??. The bounds will be expressed in terms of the A _q constant of w if q>q _w =inf?{s:w??A _s }. Our results can be regarded as a natural extension of the results about the growth of the A _p constant of singular integral operators on classical weighted Lebesgue spaces $L^{p}_{w}$ in Hytonen et al. (arXiv:1006.2530, 2010; arXiv:0911.0713, 2009), Lerner (Ill.?J.?Math. 52:653?C666, 2008; Proc. Am. Math. Soc. 136(8):2829?C2833, 2008), Lerner et?al. (Int.?Math. Res. Notes 2008:rnm 126, 2008; Math. Res. Lett. 16:149?C156, 2009), Lacey et?al. (arXiv:0905.3839v2, 2009; arXiv:0906.1941, 2009), Petermichl (Am. J. Math. 129(5):1355?C1375, 2007; Proc. Am. Math. Soc. 136(4):1237?C1249, 2008), and Petermichl and Volberg (Duke Math. J. 112(2):281?C305, 2002). Our main result is stated in Theorem?1.1. Our method avoids the atomic decomposition which was usually used in proving boundedness of singular integral operators on Hardy spaces.     

Landau–Bloch Constants for Functions in α-Bloch Spaces and Hardy Spaces

In this paper, we obtain a sharp distortion theorem for a class of functions in ??-Bloch spaces, and as an application of it, we establish the corresponding Landau??s theorem. These results generalize the corresponding results of Bonk, Minda and Yanagihara, and Liu, respectively. We also prove the existence of Landau?CBloch constant for a class of functions in Hardy spaces and the obtained result is a generalization of the corresponding result of Chen and Gauthier.     

Local Hardy–Littlewood maximal operator

In this article we define and investigate a local Hardy–Littlewood maximal operator in Euclidean spaces. It is proved that this operator satisfies weighted L ^p , p > 1, and weighted weak type (1,1) estimates with weight function ${w \in A^p_{\rm{loc}}}In this article we define and investigate a local Hardy–Littlewood maximal operator in Euclidean spaces. It is proved that this operator satisfies weighted L ^p , p > 1, and weighted weak type (1,1) estimates with weight function w ? A^p_loc{w \in A^p_{\rm{loc}}}, the class of local A _p weights which is larger than the Muckenhoupt A _p class. Also, the condition w ? A^p_loc{w \in A^p_{\rm{loc}}} turns out to be necessary for the weighted weak type (p,p), p ≥ 1, inequality to hold.     

Sharp weighted bounds for the Hardy–Littlewood maximal operators on Musielak–Orlicz spaces

Let \({\varphi}\) be a Musielak–Orlicz function satisfying that, for any \({(x,\,t)\in{\mathbb R}^n \times [0, \infty)}\), \({\varphi(\cdot,\,t)}\) belongs to the Muckenhoupt weight class \({A_\infty({\mathbb R}^n)}\) with the critical weight exponent \({q(\varphi) \in [1,\,\infty)}\) and \({\varphi(x,\,\cdot)}\) is an Orlicz function with uniformly lower type \({p^{-}_{\varphi}}\) and uniformly upper type \({p^+_\varphi}\) satisfying \({q(\varphi) < p^{-}_{\varphi}\le p^{+}_{\varphi} < \infty}\). In this paper, the author obtains a sharp weighted bound involving \({A_\infty}\) constant for the Hardy–Littlewood maximal operator on the Musielak–Orlicz space \({L^{\varphi}}\). This result recovers the known sharp weighted estimate established by Hytönen et al. in [J. Funct. Anal. 263:3883–3899, 2012].