Carleson Measures for the Bloch Space

In this paper we study the positive Borel measures μ on the unit disc in for which the Bloch space is continuously included in , 0 < p < ∞. We call such measures p-Bloch-Carleson measures. We give two conditions on a measure μ in terms of certain logarithmic integrals one of which is a necessary condition and the other a sufficient condition for μ being a p-Bloch-Carleson measure. We also give a complete characterization of the p-Bloch-Carleson measures within certain special classes of measures. It is also shown that, for p > 1, the p-Bloch-Carleson measures are exactly those for which the Toeplitz operator , defined by , maps continuously into the Bergman space A ¹, . Furthermore, we prove that if p > 1, α >-1 and ω is a weight which satisfies the Bekollé-Bonami -condition, then the measure defined by is a p-Bloch-Carleson-measure. We also consider the Banach space of those functions f which are analytic in and satisfy , as . The Bloch space is contained in . We describe the p-Carleson measures for and study weighted composition operators and a class of integration operators acting in this space. We determine which of these operators map continuously to the weighted Bergman space and show that they are automatically compact. This research is partially supported by several grants from “the Ministerio de Educación y Ciencia, Spain” (MTM2005-07347, MTM2007-60854, MTM2006-26627-E, MTM2007-30904-E and Ingenio Mathematica (i-MATH) No. CSD2006-00032); from “La Junta de Andalucía” (FQM210 and P06-FQM01504); from “the Academy of Finland” (210245) and from the European Networking Programme “HCAA” of the European Science Foundation.     

Generalized Interpolation in Bergman Spaces and Extremal Functions

In a recent paper A. Schuster and K. Seip [SchS] have characterized interpolating sequences for Bergman spaces in terms of extremal functions (or canonical divisors). As these are natural analogues in Bergman spaces of Blaschke products, this yields a Carleson type condition for interpolation. We intend to generalize this idea to generalized free interpolation in weighted Bergman spaces B^{p, α} as was done by V. Vasyunin [Va1] and N. Nikolski [Ni1] (cf.also [Ha2]) in the case of Hardy spaces. In particular we get a strong necessary condition for free interpolation in B^{p, α} on zero–sets of B^{p, α}–functions that in the special case of finite unions of B^{p, α}–interpolating sequences turns out to be also sufficient.     

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.     

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     

On some bilinear problems on weighted Hardy‐Sobolev spaces

In this paper we study the bilinear problem of characterizing the positive Borel measures μ on S ⁿ, satisfying where $H_s^2(w)$ and $H_t^2(w)$ are weighted Hardy‐Sobolev spaces, under adequate conditions on the weight w.     

A representation theorem of harmonic functions and its application to BMO on manifolds

Abstract. In this paper a representation theorem of harmonic functions on manifolds is set up.As an application, a characterization of BMO in terms of Carleson measures is obtained.     

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.      

Carleson测度与一致有界特征函数

UBC类与UBC_0类函数分别是BMOA类与VMOA类函数的亚纯推广。我们知道,对单位圆盘上的每一个解析函数,f(z),f(z)∈BMOA当且仅当(1-|z|~2)|f'(z)|~2dxdy是Carleson测度;f(z)∈VMOA当且仅当(1-|z|~2)|f'(z)|~2dxdy是消失Carleson测度。本文我们证明,对单位圆盘上的亚纯函数f(z),f(z)∈UBC_0当且仅当(1-|z|~2)f~(#2)(z)dxdy是消失Carleson测度;若f(z)∈N,则f(z)∈UBC当且仅当(1-|z|~2)f~(#2)(z)dxdy是Carleson测度;其中f~#(z)(?)|f'(z)|/(1+|f(z)|~2)。