A remark on the centered n-dimensional Hardy-Littlewood maximal function

We study the behaviour of the n-dimensional centered Hardy-Littlewood maximal operator associated to the family of cubes with sides parallel to the axes, improving the previously known lower bounds for the best constants c _n that appear in the weak type (1,1) inequalities.     

一类奇异积分算子的加权估计

假设A是一个Young函数,MD#为广义sharp极大函数.本文首先引进了LA-Hrmander条件,对于满足LA-Hrmander条件的算子T,得到了与T相关的广义sharp极大函数的估计.然后,再利用该估计得到了算子T的加权Lp范数被Hardy-Littlewood极大函数和与Aˉ相关的极大函数的加权Lp范数所控制(0相似文献   

Weak weighted inequalities for a dyadic one-sided maximal function in

In this note we introduce a dyadic one-sided maximal function defined as

where is a certain cube associated with the dyadic cube and . We characterize the pair of weights for which the maximal operator applies into weak- for .

     

The best constant in the Davis inequality for the expectation of the martingale square function

A method is introduced for the simultaneous study of the square function and the maximal function of a martingale that can yield sharp norm inequalities between the two. One application is that the expectation of the square function of a martingale is not greater than times the expectation of the maximal function. This gives the best constant for one side of the Davis two-sided inequality. The martingale may take its values in any real or complex Hilbert space. The elementary discrete-time case leads quickly to the analogous results for local martingales indexed by . Some earlier inequalities are also improved and, closely related, the Lévy martingale is embedded in a large family of submartingales.

     

REGULARITY OF POISSON EQUATION IN SOME LOGARITHMIC SPACE

In this note, the regularity of Poisson equation -△u = f with f lying in logarithmic function space Lp(LogL)a(Ω)(1＜p ＜∞, a ∈ R) is studied. The result of the note generalizes the W2,p estimate of Poisson equation in Lp(Ω).     

On unboundedness of maximal operators for directional Hilbert transforms

We show that for any infinite set of unit vectors in the maximal operator defined by

is not bounded in .

     

On weak type inequalities for dyadic maximal functions

We obtain sharp estimates for the localized distribution function of the dyadic maximal function , given the local L¹ norms of ? and of G○? where G is a convex increasing function such that G(x)/x→+∞ as x→+∞. Using this we obtain sharp refined weak type estimates for the dyadic maximal operator.     

Equivalence of operator norm for Hardy-Littlewood maximal operators and their truncated operators on Morrey spaces

We will prove that for 1相似文献   

W ~(1,p)(R~n)-BOUNDEDNESS FOR MAXIMAL FUNCTIONS

In this paper, we get W 1,p(Rn)-boundedness for tangential maximal func- tion and nontangential maximal function , which improves J.Kinnunen, P.Lindqvist and Tananka’s results.     

On maximal functions in Orlicz spaces

Let and be the functions having the representations and , where is a positive continuous function such that and is quasi-increasing. Then the maximal function is a function in Orlicz space for all if and only if there exists a positive constant such that for all .

     

On Hardy - Littlewood Maximal Functions in Orlicz Spaces

Let Φ(t) and Ψ(t) be the functions having the following representations Φ(t) = ∫a(s)ds and Ψ(t) = ∫b(s) ds, where a(s) is a positive continuous function such that ∫a(s)/s ds = + ∞ and b(s) is an increasing function such that lim_s→ ∞ b(s) = + ∞. Then the following statements for the Hardy - Littlewood maximal function M f (x) are equivalent:

• 1 (i) there exist positive constants c₁ and s₀ such that
• 1 (ii) there exist positive constant c₂ and c₃ such that

.     

H^p（D）函数的两个新刻划

证明了关于单位圆盘D上的H^p函数的两个新的等价命题。     

Endpoint estimates for the circular maximal function

We consider the problem of endpoint estimates for the circular maximal function defined by

where is the normalized surface area measure on . Let be the closed triangle with vertices . We prove that for , there is a constant such that Furthermore, .

     

鞅极大算子的加权弱型不等式

本文研究了极大算子M满足一类弱型不等式时权函数应具备的条件.利用极大算子的弱(1,1)不等式和Young不等式,证明了权函数对(u,v)此时为AΦ,Ψ权,推广了Ap,p权的理论.     

A note on the DiPerna-Lions Flows

In this note, we give a short proof for the DiPerna-Lions flows associated to ODEs following the method of Crippa and De Lellis [3]. More precisely, assume that [divb] ∈ Ll∞oc(Rd), |b|/(1 + |x| log |x|) ∈ L∞(Rd) and | b| φ(| b|) ∈ Ll1oc(Rd), where φ(r) = log log(r + c), c > 0. Then, there exists a unique regular Lagrangian flow associated with the ODE X˙(t, x) = b(X(t, x)), X(0, x) = x.     

$L^p$函数的分布函数在端点处的极限性质

We consider the limiting property of the distribution function of L~p function at endpoints 0 and ∞ and prove that for λ 0 the following two equations limλ→+∞λ~pm({x : |f(x)| λ}) = 0, limλ→0+λ~pm({x : |f(x)| λ}) = 0hold for f ∈ L~p(Rn) with 1 ≤ p ∞. This result is naturally applied to many operators of type(p, q) as well.     

On the Davis inequality in Banach function spaces

We give a characterization of those Banach function spaces in which the Davis inequality for martingales is valid. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Weighted endpoint estimates for maximal commutators associated with the sections

We prove endpoint estimates for maximal commutators for a class of singular integral operators related to the real analysis of the Monge Ampere equation.     

On area integral estimates for solutions to parabolic systems in time-varying and non-smooth cylinders

In this paper we prove results relating the (parabolic) non-tangential maximum operator and appropriate square functions in for solutions to general second order, symmetric and strongly elliptic parabolic systems with real valued and constant coefficients in the setting of a class of time-varying, non-smooth infinite cylinders . In particular we prove a global as well as a local and scale invariant equivalence between the parabolic non-tangential maximal operator and appropriate square functions for solutions of our system. The novelty of our approach is that it is not based on singular integrals, the prevailing tool in the analysis of systems in non-smooth domains. Instead the methods explored have recently proved useful in the analysis of elliptic measure associated to non-symmetric operators through the work of Kenig-Koch-Pipher-Toro and in the analysis of caloric measure without the use of layer potentials.