BMO‐ and VMO‐spaces of slice hyperholomorphic functions

In this paper we continue the study of important Banach spaces of slice hyperholomorphic functions on the quaternionic unit ball by investigating the BMO‐ and VMO‐spaces of slice hyperholomorphic functions. We discuss in particular conformal invariance and a refined characterization of these spaces in terms of Carleson measures. Finally we show the relations with the Bloch and Dirichlet space and the duality relation with the Hardy space . The importance of these spaces in the classical theory is well known. It is therefore worthwhile to study their slice hyperholomorphic counterparts, in particular because slice hyperholomorphic functions were found to have several applications in operator theory and Schur analysis.     

Composition operators on the polydisk induced by affine maps

We study the continuity of composition operators on the classical Hardy and weighted Bergman spaces of the polydisk. We show that this problem involves some delicate properties of the derivative of the symbol. In particular, we characterize continuity when the symbol is a linear self-map of the polydisk.     

Commutators on Lipschitz spaces and related function spaces

We characterize the symbol functions so that the associated commutators with symbol functions and the Hilbert transform are bounded on Lipschitz space Λ _α ^p , where 1 < p < ∞ and 0 < α < 1/p. Properties of such symbols are also discussed.      

Inverse Problems of Spectral Analysis and Carleson Interpolation

Mathematical Notes -     

Positive Toeplitz operators between the pluriharmonic Bergman spaces

We study Toeplitz operators between the pluriharmonic Bergman spaces for positive symbols on the ball. We give characterizations of bounded and compact Toeplitz operators taking a pluriharmonic Bergman space b ^p into another b ^q for 1 < p, q < ∞ in terms of certain Carleson and vanishing Carleson measures. This research was supported by KOSEF (R01-2003-000-10243-0) and Korea University Grant.     

Carleson measures on planar sets

In this paper, we investigate what are Carleson measures on open subsets in the complex plane. A circular domain is a connected open subset whose boundary consists of finitely many disjoint circles. We call a domain G multi-nicely connected if there exists a circular domain W and a conformal map ψ from W onto G such that ψ is almost univalent with respect the arclength on δW. We characterize all Carleson measures for those open subsets so that each of their components is multinicely connected and harmonic measures of the components are mutually singular. Our results suggest the extension of Carleson measures probably is up to this class of open subsets     

Operators associated with the Jacobi semigroup

The aim of this paper is to introduce some operators induced by the Jacobi differential operator and associated with the Jacobi semigroup, where the Jacobi measure is considered in the multidimensional case.In this context, we introduce potential operators, fractional integrals, fractional derivates, Bessel potentials and give a version of Carleson measures.We establish a version of Meyer’s multiplier theorem and by means of this theorem, we study fractional integrals and fractional derivates.Potential spaces related to Jacobi expansions are introduced and using fractional derivates, we give a characterization of these spaces. A version of Calderon’s Reproduction Formula and a version of Fefferman’s theorem are given.Finally, we present a definition of Triebel–Lizorkin spaces and Besov spaces in the Jacobi setting.     

On a class of lacunary series in BMOA

In this paper we consider a special class of lacunary series and we characterize their membership in the BMOA of the unit ball of Cn in terms of their Taylor coefficients. In addition, we show that a similar result holds for the class VMOA.     

M(o)bius不变的Qp空间:结果、技巧和问题

本文是关于Mobius不变的Qp函数空间方面的综述文章，给出了近10年来有关Qp函数空间的若干结果、技巧和问题。     

映入E(q,p)的复合算子

§ 1 .　Introduction　　LetD ={z:｜z｜ <1}betheunitdiskofcomplexplane,H(D)bethespaceofallana lysticfunctionsonD ,denoteLebesguemeasureonDbydm ,normalizedsothatm(D) =1.Fora ∈D ,σa(z) =a-z1- az istheMobiustransformationofDtoitselfandg(z,a) =log｜1- aza-z｜istheGreenfunctionofDwithsingularityata.Everyanalyticself mapφ :D →DoftheunitdiskinducesthroughcompositionalinearcompositionoperatorCφfromH(D)toitself.Itisawell knownconsequenceofLittlewood’ssubordinationprinciple( [1],[2 ])that…