HANKEL OPERATORS ON HARDY SPACES AND SCHATTEN CLASSES

For a holomorphic function f on the unit ball B~N of C~N, it is proved that the reduced Hankel oporator R_f on Hardy space H~2(B~N) is of Schatten class S_p for p≥1 if and only if f is in a corresponding Sobolev space.     

A refinement about estimation of expansion coefficients for normalized biholomorphic mappings

A refining estimation of homogeneous expansion for / is discussed, where f belongs to a subclass of all normalized biholomorphic mappings defined on the unit polydisk in Cn or the unit ball in complex Banach spaces, and x = 0 is a zero of order k 1 of f(x)-x. Moreover, an estimation of homogeneous expansion for subordinate mappings defined on the unit ball in complex Banach spaces is also given.     

Sharp Growth Theorems and Coefficient Bounds for Starlike Mappings in Several Complex Variables

Let B be the unit ball in a complex Banach space. Let S^＊k＋1（B） be the family of normalized starlike mappings f on B such that z = 0 is a zero of order k ＋ 1 of f（z） - z. The authors obtain sharp growth and covering theorems, as well as sharp coefficient bounds for various subsets of S^＊k＋1（B）.     

Homeomorphic extension of strongly spirallike mappings in C~n

In this paper we consider a proper subclass nA of the full class of spirallike mappings on the Euclidean unit ball Bn in Cn with respect to a given linear operator A. We use the method of subordination chains to obtain an upper growth result for nA , and we obtain various examples of mappings in the same class of normalized biholomorphic mappings on the unit ball Bn in Cn . We also prove that the class nA is compact, while the full class of spirallike mappings with respect to a linear operator need not be compact in dimension n≥2, even when the operator is diagonal. This is one of the motivations for considering the class nA . Finally we prove that if f is a quasiregular strongly spirallike mapping on Bn such that ||[Df(z)]-1 Af(z)|| is uniformly bounded on Bn , then f extends to a homeomorphism of R2n onto itself. In addition, if A + A* = 2aI n for some a 0, this extension is also quasiconformal on R2n .     

单位球Bn上的Bohr不等式

Bohr＇s type inequalities are studied in this paper： if f is a holomorphic mapping from the unit ball B^n to B^n, f（0）=p, then we have sum from k=0 to∞｜DφP（P）[D^kf（0）（z^k）]｜/k!｜｜DφP（P）｜｜〈1 for｜z｜〈max{1/2＋｜P｜,（1-｜p｜）/2^1/2andφ_P ∈Aut（B^n） such thatφ_（p）=0. As corollaries of the above estimate, we obtain some sharp Bohr＇s type modulus inequalities. In particular, when n=1 and ｜P｜→1, then our theorem reduces to a classical result of Bohr.     

Toeplitz and Hankel Products on Bergman Spaces of the Unit Ball

The authors give some new necessary conditions for the boundedness of Toeplitz products Tf^aTg^a on the weighted Bergman space Aa^2 of the unit ball, where f and g are analytic on the unit ball. Hankel products HfH9^＋ on the weighted Bergman space of the unit ball are studied, and the results analogous to those Stroethoff and Zheng obtained in the setting of unit disk are proved.     

New Subclasses of Biholomorphic Mappings and the Modified Roper-Suffridge Operator

The authors propose a new approach to construct subclasses of biholomorphic mappings with special geometric properties in several complex variables. The RoperSuffridge operator on the unit ball B~n in C~n is modified. By the analytical characteristics and the growth theorems of subclasses of spirallike mappings, it is proved that the modified Roper-Suffridge operator [Φ_(G,γ)(f)](z) preserves the properties of S_Ω~*(A, B), as well as strong and almost spirallikeness of type β and order α on B~n. Thus, the mappings in S_Ω~*(A, B), as well as strong and almost spirallike mappings, can be constructed through the corresponding functions in one complex variable. The conclusions follow some special cases and contain the elementary results.     

Composition Cesàro Operator on the Normal Weight Zygmund Space in High Dimensions

Let n>1 and B be the unit ball in n dimensions complex space Cⁿ.Suppose thatφis a holomorphic self-map of B andψ∈H(B)withψ(0)=0.A kind of integral operator,composition Cesàro operator,is defined by T_φψ(f)(z)=∫¹0f[φ(tz)]Rψ(tz)dt/t,f∈(B)z∈B.In this paper,the authors characterize the conditions that the composition Cesàro operator T_φ,ψis bounded or compact on the normal weight Zygmund space Z_μ(B).At the same time,the sufficient and necessary conditions for all cases are given.     

On quasi-convex mappings of orderαin the unit ball of a complex Banach space Dedicated to Professor Sheng GONG on the occasion of his 75th birthday

In this paper, a class of biholomorphic mappings named quasi-convex mapping of order a in the unit ball of a complex Banach space is introduced. When the Banach space is confined to Cn, we obtain the relation between this class of mappings and the convex mappings. Furthermore, the growth and covering theorems of this class of mappings are given on the unit ball of a complex Banach space X. Finally, we get the second order terms coefficient estimations of the homogeneous expansion of quasi-convex mapping of order a defined on the polydisc in Cn and on the unit ball in a complex Banach space, respectively.     

单位球B~n上的Bohr不等式(英文)

Bohr's type inequalities are studied in this paper: if f is a holomorphic mapping from the unit ball B~n to B~n, f(0)=p, then we have sum from k=0 to∞|Dφ_P(P)[D~kf(0)(z~k)]|／k!||Dφ_P(P)||＜1 for|z|＜max{1／2 |P|,(1-|p|)／2~(1／2)andφ_P∈Aut(B~n) such thatφ_(p)=0. As corollaries of the above estimate, we obtain some sharp Bohr's type modulus inequalities. In particular, when n=1 and |P|→1, then our theorem reduces to a classical result of Bohr.     

单位球加权伯格曼空间上托普里兹算子的乘积

We consider the question for what kind of square integrable holomorphic functions f,g on the unit ball the densely defined products TfTg-are invertible and Fredholm on the weighted Bergman space of the unit ball.We furthermore obtain necessary and sufficient conditions for bounded Haplitz products HfTg-,where f∈L2(Bn,dvα) and g is a square integrable holomorphic function.     

The commutants of analytic Toeplitz operators for several complex variables

It is proved that if  is a nonconstant bounded analytic function on the unit ball B n and continuous on S n in C n , and ψ is a bounded measurable function on S n such that T * and T ψ commute, then ψ is the boundary value of an analytic function on B n . In addition, the commutants of two Toeplitz operators are also discussed.     

ON CRITERION OF THE EXTREMALITY AND CONSTRUCTION OF HAMILTON SEQUENCES FOR A CLASS OF TEICHMULLER MAPPINGS

It is proved that if f is a Teichmiiller self-mapping of the unit disk with a holomorphic quadratic differential φ,and φ satisfies the growth condition m(φ,r)=1/2π∫0^2π|φ（reiθ）|dθ=o((1-r)^-s),r→1,for any s >1,then f is extremal,and there exists a sequence {tn},0<tn<1,lim tn=1,such that {φ(tnz)} is a Hamilton ssquence.It is the preclsion of a theorem of Reich-Strebel in 1974,and gives a fairly satisfactory answer to a question of Reich is 1988。     

EXTENDED CESARO OPERATORS ON THE BLOCH SPACE IN THE UNIT BALL OF C^n

The paper defines an extended Ceshro operator Tg with holomorphic symbol g in the unit ball B of C^n as Tg(f)(z) =∫^10f(tz)Rg(tz)dt/t, f∈H(B),z ∈ B. Where Rg(z) =∑^nj=1 zjθg/θzj is the radial derivative of g. In this paper, the author charac-terizes g for which Tg is bounded (or compact) on the Bloch space B and the little Bloch space B0.     

Sharp distortion theorems for a subclass of close-to-convex mappings

We introduce the class of strongly close-to-convex mappings of order c~ in the unit ball of a complex Banach space, and then, we give the sharp distortion theorems for this class of mappings in the unit ball of a complex Hilbert space X or the unit polydisc in Cn. As an application, a sharp growth theorem for strongly close-to-convex mappings of order α is obtained.     

Commuting of Toeplitz Operators in Several Complex Variables

1 IntroductionLet be the unit ball Bn or the polydisk Dn in Cn, and dA denote the Lebesgue measure on , normalized so that the measure of equals 1. L2/a() is The Bergman space. For z, the Bergman reproducing kernel is a function Kz L2/a). The normalized Bergman reproducing kernel k is the function Kz Kz2. Here, as elsewhere in this paper, the norm 2 and the inner product are taken in the space L2(,dA).Let P denote the orthogonal projection of L2(, dA) onto L2/a(). For a function f L …     

Packing Constant and Strong Extreme Point in Orlicz Spaces

Packing constant is an important and interesting geometric parameter.Packingconstant A_x of Banach space is a real number such that if r≤A_x,then a infinitenumber of spheres of radius r can be packed in the unit ball U(X),and if r>A_x,only a finite number of spheres can be done.It began in the 1950 studyingpacking constant of special sequence spaces.Rankin found A_2 and A_p of space l_2and l_p(p>1)respectively in 1955 and in 1958.In 1976,Cleaver discussed Orliczsequence space equipped with Orlicz norm [l_M, ||·||_M]·under a strong condition,     

CRITERIA FOR AN ANALYTIC FUNCTION BELONGING TO THE Q_K SPACES

The author gives a mild integral condition in a nondecreasing function K : [0, ∞) → [0, ∞), which is sufficient and the best possible to ensure that f is a Bloch function if and only if f belongs to QK, a Mbius-invariant space of functions analytic in the unit disk. Their contributions are slight improvements of known results, and the proofs presented here are independently developed. The corresponding results for meromorphic case are also given.     

A proof of Sethares'''' conjecture

Let (?)(z) be holomorphic in the unit disk △ and meromorphic on △. Suppose / is a Teichmuller mapping with complex dilatation In 1968, Sethares conjectured that f is extremal if and only if either (i)(?) has a double pole or (ii)(?) has no pole of order exceeding two on (?)△. The "if" part of the conjecture had been solved by himself. We will give the affirmative answer to the "only if" part of the conjecture. In addition, a more general criterion for extremality of quasiconformal mappings is constructed in this paper, which generalizes the "if" part of Sethares' conjecture and improves the result by Reich and Shapiro in 1990.     

Bloch Constant of Holomorphic Mappings on the Unit Ball of C~n

In this paper,the authors establish distortion theorems for various subfamilies H_k(B)of holomorphic mappings defined in the unit ball in C~n with critical points,where k is any positive integer.In particular,the distortion theorem for locally biholomorphic mappings is obtained when k tends to ∞.These distortion theorems give lower bounds on|det f′(z)|and Re det f′(z).As an application of these distortion theorems,the authors give lower and upper bounds of Bloch constants for the subfamiliesβ_k(M)of holomorphic mappings.Moreover,these distortion theorems are sharp.When B is the unit disk in C,these theorems reduce to the results of Liu and Minda.A new distortion result of Re det f′(z)for locally biholomorphie mappings is also obtained.