Multilinear Fractional Integral Operators: A counter-example

具有Dini型核的多线性分数次Calderón-Zygmund算子

Multilinear fractional Calderón-Zygmund operators with Dini type kernel

本文研究具有Dini型核的多线性分数次Calderón-Zygmund算子，证明其端点弱型估计，并在变指数Lebesgue空间上建立有界性。

Multilinear fractional integral operators on non-homogeneous metric measure spaces

Let $(X,d,μ)$ be a non-homogeneous metric measure space satisfying both the geometrically doubling and the upper doubling measure conditions. In this paper, the boundedness of multilinear fractional integral operator in this setting is proved. Via a sharp maximal operator, the boundedness of commutators generated by multilinear fractional integral operator with $RBMO(μ)$ function on non-homogeneous metric measure spaces in Lebesgue spaces is obtained.

Sharp Weighted Bounds for Multilinear fractional Maximal type Operators with Rough Kernels

In this paper, we will give the weighted bounds for multilinear fractional maximal type operators $\mathcal{M}_{Ω,α}$ with rough homogeneous kernels. We obtain a mixed $A_{(\vec{P},q)}-A_\infty$ bound and a $A_{\vec{P}}$ type estimate for $\mathcal{M}_{Ω,α}$. As an application, we give an almost sharp estimate for the multilinear fractional integral operator with rough kernels $\mathcal{I}_{Ω,α}$.

On multilinear fractional strong maximal operator associated with rectangles and multiple weights

In this paper, the multilinear fractional strong maximal operator $\mathcal{M}_{\mathcal{R},α}$ associated with rectangles and corresponding multiple weights $A_{(\vec{p},q),\mathcal{R}}$ are introduced. Under the dyadic reverse doubling condition, a necessary and sufficient condition for two-weight inequalities is given. As consequences, we first obtain a necessary and sufficient condition for one-weight inequalities. Then, we give a new proof for the weighted estimates of multilinear fractional maximal operator $\mathcal{M}_α$ associated with cubes and multilinear fractional integral operato…

Weighted mixed weak-type inequalities for multilinear fractional operators

The aim of this paper is to obtain mixed weak-type inequalities for multilinear fractional operators, extending results by F. Berra, M. Carena and G. Pradolini \cite{BCP}. We prove that, under certain conditions on the weights, there exists a constant $C$ such that $$\Bigg\| \frac{\mathcal G_α(\vec f \,)}{v}\Bigg\|_{L^{q, \infty}(νv^q)} \leq C \ \prod_{i=1}^m{\|f_i\|_{L^1(u_i)}},$$ where $\mathcal G_α(\vec f \,)$ is the multilinear maximal function $\mathcal M_α(\vec f\,)$ that was introduced by K. Moen in \cite{M} or the multilineal fractional integral $\mathcal I_α(\vec f \,)$. As an applica…

Weighted Estimates for the iterated Commutators of Multilinear Maximal and Fractional Type Operators

In this paper, the following iterated commutators $T_{*,Πb}$ of maximal operator for multilinear singular integral operators and $I_{α, Πb}$ of multilinear fractional integral operator are introduced and studied $$\aligned T_{*,Πb}(\vec{f})(x)&=\sup_{δ>0}\bigg|[b_1,[b_2,...[b_{m-1},[b_m,T_δ]_m]_{m-1}...]_2]_1 (\vec{f})(x)\bigg|,$$ $$\aligned I_{α, Πb}(\vec{f})(x)&=[b_1,[b_2,...[b_{m-1},[b_m,I_α]_m]_{m-1}...]_2]_1 (\vec{f})(x),$$ where $T_δ$ are the smooth truncations of the multilinear singular integral operators and $I_α$ is the multilinear fractional integral operator, $b_i\in BMO$ for $i=1,…

广义Morrey空间中分层李群上若干多重线性分数次积分算子的有界性

Boundness of Some Multilinear Fractional Integral Operators in Generalized Morrey Spaces on Stratified Lie Groups

本文研究分层李群上广义Morrey空间中多重线性分数次积分与极大算子的Spanne型有界性。

Optimal parameters related with continuity properties of the multilinear fractional integral operator between Lebesgue and Lipschitz spaces

We deal with the boundedness of the multilinear fractional integral operator $I_{γ,m}$ from a product of weighted Lebesgue spaces into adequate weighted Lipschitz spaces. Our results generalize some previous estimates not only for the linear case but also for the unweighted problem in the multilinear context. We characterize the classes of weights for which the problem described above holds and show the optimal range of the parameters involved. The optimality is understood in the sense that the parameters defining the corresponding spaces belong to a certain region. We further exhibit examples…

多线性设置中超越极值的 $\oldsymbol{p}$ 值相关的分数阶算子若干交换子的平滑性性质

Smoothness properties related to several commutators of fractional operators for values of $\boldsymbol{p}$ beyond the extreme in the multilinear setting

本文证明了多线性分数阶算子高阶交换子从加权 Lebesgue 空间乘积到加权 Lipschitz 空间的连续性，推广了无权和线性情形的估计，并完整分析了相关多线性权性质及最优参数区域。

On the Multilinear Fractional Integral Operators with Correlation Kernels

In this paper, we study a class of multilinear fractional integral operators which have correlation kernels $\prod_{1\leq i<j \leq k}|x_i-x_j|^{-α_{ij}}$. The necessary and sufficient conditions are obtained under which these oprators are bounded from $L^{p_1}\times \cdots \times L^{p_k}$ into $L^q$. As a consequence, we also get the endpoint estimates from $L^{p_1}\times \cdots \times L^{p_k}$ to $BMO$ of these operators.

具有分数阶秩的非退化多线性奇异乘子

Non-Degenerate Multilinear Singular Multipliers with Fractional Rank

本研究针对满足m维线性子空间外符号估计的多线性乘子，建立了其作用于ℝᵈ上(n-1)元函数组的Lᵖ估计，重点分析了分数阶秩情形下的相关性质，为多线性奇异乘子的有界性研究提供了新结果。

Extension of Multilinear Fractional Integral Operators to Linear Operators on Lebesgue Spaces with Mixed Norms

In [C. E. Kenig and E. M. Stein, Multilinear estimates and fractional integration, Math. Res. Lett., 6(1):1-15, 1999], the following type of multilinear fractional integral \[ \int_{\mathbb{R}^{mn}} \frac{f_1(l_1(x_1,\ldots,x_m,x))\cdots f_{m+1}(l_{m+1}(x_1,\ldots,x_m,x))}{(|x_1|+\ldots+|x_m|)^λ} dx_1\ldots dx_m \] was studied, where $l_i$ are linear maps from $\mathbb{R}^{(m+1)n}$ to $\mathbb{R}^n$ satisfying certain conditions. They proved the boundedness of such multilinear fractional integral from $L^{p_1}\times \ldots \times L^{p_{m+1}}$ to $L^q$ when the indices satisfy the homogeneity c…

Two-weighted estimates of the multilinear fractional integral operator between weighted Lebesgue and Lipschitz spaces with optimal parameters

Given an $m$-tuple of weights $\vec{v}=(v_1,\dots,v_m)$, we characterize the classes of pairs $(w,\vec{v})$ involved with the boundedness properties of the multilinear fractional integral operator from $\prod_{i=1}^mL^{p_i}\left(v_i^{p_i}\right)$ into suitable Lipschitz spaces associated to a parameter $δ$, $\mathcal{L}_w(δ)$. Our results generalize some previous estimates not only for the linear case but also for the unweighted problem in the multilinear context. We emphasize the study related to the range of the parameters involved with the problem described above, which is optimal in the se…

Weak factorizations of the Hardy space in terms of multilinear fractional integral operator

We give a constructive proof of the factorization theorem for the classical Hardy space in terms of fractional integral operator. Moreover, the result is extended to the multilinear case and weighted case. As an application, we obtain the characterization of $BMO$ via the weighted boundedness of commutators of the multilinear fractional integral operator, without individual conditions on the weights class.

多线性分数次极大算子与积分算子及其交换子在广义加权Morrey空间上的刻画及应用

Characterizations for multilinear fractional maximal and integral operators and their commutators on generalized weighted Morrey spaces and applications

本文研究了多线性分数次极大与积分算子及其交换子在广义加权Morrey空间上的有界性，证明了两种有界性刻画，并应用于Besov-Morrey空间有界性、嵌入定理及次拉普拉斯算子先验估计。

Some extensions of classes involving pair of weights related to the boundedness of multilinear commutators associated to generalized fractional integral operators

We deal with the boundedness properties of higher order commutators related to some generalizations of the multilinear fractional integral operator of order $m$, $I_α^m$, from a product of weighted Lebesgue spaces into adequate weighted Lipschitz spaces, extending some previous estimates for the linear case. Our study includes two different types of commutators and sufficient conditions on the weights in order to guarantee the continuity properties described above. We also exhibit the optimal range of the parameters involved. The optimality is understood in the sense that the parameters defini…

On the behaviors of rough multilinear fractional integral and multi-sublinear fractional maximal operators both on product L^{p} and weighted L^{p} spaces

The aim of this paper is to get the product Lp-estimates, weighted estimates and two-weighted estimates for rough multilinear fractional integral operators and rough multi-sublinear fractional maximal operators, respectively. The author also studies two-weighted weak type estimate on product Lp (Rn) for rough multi-sublinear fractional maximal operators. In fact, this article is the rough kernel versions of [4, 5]' s results.

On two-weight norm estimates for multilinear fractional maximal function

We prove some Sawyer-type characterizations for multilinear fractional maximal function for the upper triangle case. We also provide some two-weight norm estimates for this operator. As one of the main tools, we use an extension of the usual Carleson Embedding that is an analogue of the P. L. Duren extension of the Carleson Embedding for measures.

Multilinear singular operators with fractional rank

We prove bounds for multilinear operators on $\R^d$ given by multipliers which are singular along a $k$ dimensional subspace. The new case of interest is when the rank $k/d$ is not an integer. Connections with the concept of {\em true complexity} from Additive Combinatorics are also investigated.

多线性分数阶稀疏算子理论 II：通过多线性分数阶稀疏形式改进加权估计

The multilinear fractional sparse operator theory II: refining weighted estimates via multilinear fractional sparse forms

本文通过引入新的多线性分数阶稀疏形式和权类，改进多线性分数阶奇异积分算子广义交换子的加权估计，获得尖锐定量界并应用于分数阶Laplacian方程解的正则性。

多线性嵌入定理对于分数稀疏算子

Multilinear embedding theorem for fractional sparse operators

本文研究了分数稀疏算子的多线性嵌入定理的充分条件，通过验证这些条件，建立了幂权重下的定理，并提供了Schrodinger算子的Morrey型充分条件。

Hardy 型空间估计：多线性分数次积分算子

Hardy type spaces estimates for multilinear fractional integral operators

本文证明了多线性分数次积分算子在多种广义 Hardy 空间上的有界性，并推广了现有理论。

多线性分数次有界平均振荡算子理论 I：稀疏控制、稀疏 $T1$ 定理、非对角外推、定量加权估计——针对广义交换子

The multilinear fractional bounded mean oscillation operator theory I: sparse domination, sparse $T1$ theorem, off-diagonal extrapolation, quantitative weighted estimate -- for generalized commutators

本文在球基测度空间上引入并研究了多线性分数次有界平均振荡算子及其广义交换子，建立了稀疏控制与稀疏 $T1$ 定理，并在多线性分数次权下获得了多种加权不等式与非对角外推框架。

Two-weight inequalities for multilinear maximal functions in Orlicz spaces

In this note, we provide various two-weight norm estimates of the multi-linear fractional maximal function and weighted maximal function between different Orlicz spaces. More precisely, we obtain Sawyer-type characterizations and norm estimates for these operators.

Characterization of Lipschitz Functions via Commutators of Multilinear Singular Integral Operators in Variable Lebesgue Spaces

In this paper, the main aim is to consider the boundedness of commutators of multilinear Calderón-Zygmund operators with Lipschitz functions in the context of the variable exponent Lebesgue spaces. Furthermore, the variable versions of the Lipschitz spaces are also discussed, and with the help of a key tool of a pointwise estimate involving the sharp maximal operator of the multilinear fractional commutator and certain associated maximal operators.

多线性分数阶稀疏算子理论I：逐点控制与加权估计

The multilinear fractional sparse operator theory I: pointwise domination and weighted estimate

本文针对多线性分数阶奇异积分算子的广义交换子，通过引入高阶多符号稀疏算子并利用极大权与迭代权方法，建立了Bloom型定量加权估计及端点估计，改进了现有方法并推广了结论。

Regularity and continuity of local Multilinear Maximal type operator

This paper will be devoted to study the regularity and continuity properties of the following local multilinear fractional type maximal operators, $$\mathfrak{M}_{α,Ω}(\vec{f})(x)=\sup\limits_{0<r<{\rm dist}(x,Ω^c)}\frac{r^α}{|B(x,r)|^m}\prod\limits_{i=1}^m\int_{B(x,r)}|f_i(y)|dy,\quad \hbox{for \ }0\leqα<mn,$$ where $Ω$ is a subdomain in $\mathbb{R}^n$, $Ω^c=\mathbb{R}^n\backslashΩ$ and $B(x,r)$ is the ball in $\mathbb{R}^n$ centered at $x$ with radius $r$. Several new pointwise estimates for the derivative of the local multilinear maximal function $\mathfrak{M}_{0,Ω}$ and the fractional maxi…

Two-weight inequalities for multilinear commutators

We prove Bloom type two-weight inequalities for commutators of multilinear singular integral operators including Calderón-Zygmund operators and their dyadic counterparts. Such estimates are further extended to a general higher order multilinear setting. The proof involves a pointwise sparse domination of multilinear commutators.

$A_p$-$A_\infty$ estimates for multilinear maximal and sparse operators

We obtain mixed $A_p$--$A_\infty$ estimates for a large family of multilinear maximal and sparse operators. Operators from this family are known to control for instance multilinear Calderón--Zygmund operators, square functions, fractional integrals, and the bilinear Hilbert transform. Our results feature a new multilinear version of the Fujii--Wilson $A_\infty$ characteristic that allows us to recover the best known estimates in terms of the $A_p$ characteristic for dependent weights as a special case of the mixed characteristic estimates for general tuples of weights.

On the Boundedness of Multilinear Fractional Strong Maximal Operator with multiple weights

In this paper, we investigated the boundedness of multilinear fractional strong maximal operator $\mathcal{M}_{\mathcal{R},α}$ associated with rectangles or related to more general basis with multiple weights $A_{(\vec{p},q),\mathcal{R}}$. In the rectangles setting, we first gave an end-point estimate of $\mathcal{M}_{\mathcal{R},α}$, which not only extended the famous linear result of Jessen, Marcinkiewicz and Zygmund, but also extended the multilinear result of Grafakos, Liu, Pérez and Torres ($α=0$) to the case $0<α<mn.$ Then, in one weight case, we gave several equivalent characterizations…

Sharp bounds for multilinear curved Kakeya, restriction and oscillatory integral estimates away from the endpoint

We revisit the multilinear Kakeya, curved Kakeya, restriction, and oscillatory integral estimates that were obtained in paper of Bennett, Carbery, and the author using a heat flow monotonicity method applied to a fractional Cartesian product, together with induction on scales arguments. Many of these estimates contained losses of the form $R^\varepsilon$ (or $\log^{O(1)} R$) for some scale factor $R$. By further developing the heat flow method, and applying it directly for the first time to the multilinear curved Kakeya and restriction settings, we are able to eliminate these losses, as long a…

Multilinear integral operators and mean oscillation

In this paper, the boundedness properties for some multilinear operators related to certain integral operators from Lebesgue spaces to Orlicz spaces are obtained. The operators include Calderón--Zygmund singular integral operator, fractional integral operator, Littlewood--Paley operator and Marcinkiewicz operator.

Generalized Fractional Integrals and Their Commutators over Non-homogeneous Metric Measure Spaces

Let $({\mathcal X},d,μ)$ be a metric measure space satisfying both the upper doubling and the geometrically doubling conditions. In this paper, the authors establish some equivalent characterizations for the boundedness of fractional integrals over $({\mathcal X},d,μ)$. The authors also prove that multilinear commutators of fractional integrals with ${\mathop\mathrm{\,RBMO(μ)}}$ functions are bounded on Orlicz spaces over $({\mathcal X},d,μ)$, which include Lebesgue spaces as special cases. The weak type endpoint estimates for multilinear commutators of fractional integrals with functions in t…

新型分数型权与若干算子的有界性

New fractional type weights and the boundedness of some operators

本文建立了两类分数型变指标权，分别刻画多线性分数型算子及其交换子在加权变指标 Lebesgue 空间上的有界性，并推广了已有的矩阵权结果。

Some Weighted Estimates on Gaussian Measure Spaces

In this paper, we obtain the weighted boundedness for the local multi(sub)linear Hardy-Littlewood maximal operators and local multilinear fractional integral operators associated with the local Muckenhoupt weights on Gaussian measure spaces. We deal with these problems by introducing a new pointwise equivalent "radial" definitions of these local operators. Moreover using a similar approach, we also get the weighted boundedness for the local fractional maximal operators with rough kernel and local fractional integral operators with rough kernel on Gaussian measure spaces.

Multilinear estimates for Calderón commutators

In this paper, we investigate the multilinear boundedness properties of the higher ($n$-th) order Calderón commutator for dimensions larger than two. We establish all multilinear endpoint estimates for the target space $L^{\frac{d}{d+n},\infty}(\mathbb{R}^d)$, including that Calderón commutator maps the product of Lorentz spaces $L^{d,1}(\mathbb{R}^d)\times\cdots\times L^{d,1}(\mathbb{R}^d)\times L^1(\mathbb{R}^d)$ to $L^{\frac{d}{d+n},\infty}(\mathbb{R}^d)$, which is the higher dimensional nontrivial generalization of the endpoint estimate that the $n$-th order Calderón commutator maps $L^{1}…

Multilinear singular integrals on non-commutative $L^p$ spaces

We prove $L^p$ bounds for the extensions of standard multilinear Calderón-Zygmund operators to tuples of UMD spaces tied by a natural product structure. This can, for instance, mean the pointwise product in UMD function lattices, or the composition of operators in the Schatten-von Neumann subclass of the algebra of bounded operators on a Hilbert space. We do not require additional assumptions beyond UMD on each space - in contrast to previous results, we e.g. show that the Rademacher maximal function property is not necessary. The obtained generality allows for novel applications. For instance…

极大多重线性算子

Maximal multilinear operators

本文为一类单变量极大多重线性平均建立 $L^p$ 界，推广了 Lacey 的双线性结果，并应用于几乎处处收敛及动力系统遍历对应物。

加权Riesz-Kolmogorov准则与变指数Lebesgue空间上紧性的多线性外推

Compact sets in quasi-Banach function spaces and multilinear extrapolation of compactness on $L^{p(\cdot)}(w)$

本文通过建立加权Riesz-Kolmogorov定理，在变指数Lebesgue空间上实现了多线性紧算子的外推，并得到了交换子、分数次积分和Fourier乘子的新加权紧性估计。

Banach-valued multilinear singular integrals

We develop a general framework for the analysis of operator-valued multilinear multipliers acting on Banach-valued functions. Our main result is a Coifman-Meyer type theorem for operator-valued multilinear multipliers acting on suitable tuples of UMD spaces. A concrete case of our theorem is a multilinear generalization of Weis' operator-valued Hörmander-Mihlin linear multiplier theorem. Furthermore, we derive from our main result a wide range of mixed $L^p$-norm estimates for multi-parameter multilinear paraproducts, leading to a novel mixed norm version of the partial fractional Leibniz rule…

具有齐次核的多线性分数次极大算子与积分算子、Hardy--Littlewood--Sobolev及Olsen型不等式

Multilinear fractional maximal and integral operators with homogeneous kernels, Hardy--Littlewood--Sobolev and Olsen-type inequalities

本文针对具有齐次核的多线性分数次极大算子与积分算子，利用Hedberg和Adams的思想，证明了其在不同函数空间（含弱型空间）的有界性，得到Hardy--Littlewood--Sobolev及Olsen型不等式相关结果。

Regularity and continuity of the multilinear strong maximal operators

Let $m\ge 1$, in this paper, our object of investigation is the regularity and and continuity properties of the following multilinear strong maximal operator $${\mathscr{M}}_{\mathcal{R}}(\vec{f})(x)=\sup_{\substack{R \ni x R\in\mathcal{R}}}\prod\limits_{i=1}^m\frac{1}{|R|}\int_{R}|f_i(y)|dy,$$ where $x\in\mathbb{R}^d$ and $\mathcal{R}$ denotes the family of all rectangles in $\mathbb{R}^d$ with sides parallel to the axes. When $m=1$, denote $\mathscr{M}_{\mathcal{R}}$ by $\mathcal {M}_{\mathcal{R}}$.Then, $\mathcal {M}_{\mathcal{R}}$ coincides with the classical strong maximal function initia…

Fractional series operators on discrete Hardy spaces

We estudy the $H^{p}(\mathbb{Z})$ - $\ell^{q}(\mathbb{Z})$ boundedness of the fractional series operator $T_γ$ given by \[ (T_γb)(j) = \sum_{i \neq \pm j} \frac{b(i)}{|i-j|^α|i+j|^β}, \] where $0 \leq γ< 1$, $α, β> 0$ and $α+ β= 1 -γ$. By means of a counter-example, we also show that the operator $T_γ$ is not bounded from $H^{p}(\mathbb{Z})$ into $H^{q}(\mathbb{Z})$.

Fractional Hardy inequalities and visibility of the boundary

We prove fractional order Hardy inequalities on open sets under a combined fatness and visibility condition on the boundary. We demonstrate by counterexamples that fatness conditions alone are not sufficient for such Hardy inequalities to hold. In addition, we give a short exposition of various fatness conditions related to our main result, and apply fractional Hardy inequalities in connection to the boundedness of extension operators for fractional Sobolev spaces.

Sobolev space estimates for a class of bilinear pseudodifferential operators lacking symbolic calculus

The reappearance of a sometimes called exotic behavior for linear and multilinear pseudodifferential operators is investigated. The phenomenon is shown to be present in a recently introduced class of bilinear pseudodifferential operators which can be seen as more general variable coefficient counterparts of the bilinear Hilbert transform and other singular bilinear multipliers operators. The unboundedness on product of Lebesgue spaces but the boundedness on spaces of smooth functions (which is the exotic behavior referred to) of such operators is obtained. In addition, by introducing a new way…

A boundary-value problem for a mixed type equation involving hyper-Bessel fractional differential operator and Hilfer's bi-ordinal fractional derivative

In a rectangular domain, a boundary-value problem is considered for a mixed-type equation with a regularized Caputo-like counterpart of hyper-Bessel differential operator and the bi-ordinal Hilfer's fractional derivative. Using the method of separation of variables, Laplace transform, a unique solvability of the considered problem has been established. Moreover, we have found the explicit solution of initial problems for a differential equation with the bi-ordinal Hilfer's derivative and regularized Caputo-like counterpart of the hyper-Bessel differential operator with the non-zero starting po…