单位球上加权Bergman空间的复合型算子

本文给出了Cn中单位球上加权Bergman空间Apα到Bloch型空间βq的加权复合算子Tψ,φ为有界算子和紧算子的简捷充要条件,同时给出了如下结果:(1)若复合算子Cφ在Apα上有界,则Cφ在Apα上紧的充要条件是lim|z|→1-1-|z|/1-|φ(z)|=0.该结果改进了Zhu的相应结果.(2)复合算子Cφ是Apα到βn+1+α+p/p紧算子的充要条件是lim|z|→1-1-|z|/1-|φ(z)|=0.     

广义Bergman空间上的紧复合算子

首先证明广义Bergman空间A_(N,α)~p,(α-n-1,p0)上的复合算子C_φ的有界性和紧性是不依赖于p的,进而证明了若对某个q0和-n-1βα,C_φ在A_(N,β)~α上有界,则C_φ在A_(N,α)~p,α(α-n-1,p0)上是紧的当且仅当lim|z|→1-1-(|z|~2/1-|φ(1)|~2)=0.     

Zygmund空间上的微分复合算子

讨论Zygmund空间E={f∈H(D):sup_(z∈D)(l-|z|~2)|f″(z)|∞}上的微分复合算子DC_φ,这里C_φ是复合算子,D是微分算子.得到了DC_φ在Zygmund空间E和小Zygmund空间E_0上是有界算子与紧算子的充分必要条件.     

几个算子不等式的最佳常数

该文给出了单位圆上解析函数中φ(z),|φ(z)<1,对于 Hilbert空间 H上任一真压缩算子 A,算子φ(A)的范数估计,得出 sup b~2(φ)=2, sup b~2(φ)=1. b(φ)=sup(||φ(A)||(1-||A||~2) ||φ(A)||~2)~(1/2),b(φ)=sup{||φ(A)||(1-||A||~2) inf ||φ(A)x||~2}~(1/2),这里A取遍H上一切真压缩算子,并且若φ(z)=sum from σ=0 to n(0/σ),|φ(z)|,|φ(z)|<1,则||φ(A)|| ||φ(A)||≤2n,其中φ(z)=z~nφ(z~(-1)),且2是与n,φ(z)及A无关常数中的最小者.     

单位球的Bergman空间上Schatten类加权复合算子

本文研究了单位球的Bergman空间上Schatten类加权复合算子,得到了这种加权复合算子属于Schatten-Von Neumann.理想S_p的几个充要条件.作为推论给出了Wφ,φ是一个Hilbert- Schmidt算子的充要条件是∫_(Bn)(|ψ(ω)|~2)/((1-|φ(ω)|~2)~(n 1)dV(ω)<∞..     

C～n中单位球上μ-Bloch函数的等价刻画

设μ是[0,1)上的正规函数,给出了C~n中单位球B上μ-Bloch空间β_μ中函数的几种刻画.证明了下列条件是等价的:(1)f∈β_μ;(2)f∈H(B)且函数μ(|z|)(1-|z|~2)~(γ-1)R~(α,γ)f(z)在B上有界;(3)f∈H(B)且函数μ(|z|)(1-|z|~2)~M_1-1M_1f/_zm(z)在B上有界,其中|m|=M_1;(4)f∈H(B)且函数μ(|z|)(1-|z|~2)M_2-1R~(M_2)f(z)在B上有界.     

Dirichlet空间上一类乘法算子的酉等价类

本文研究了Dirichlet空间D上由二阶Blaschke积φ定义的乘法算子M_φ的酉等价类.主要结果表明对于D的一个乘子ψ,乘法算子M_ψ酉等价于M_φ当且仅当存在常数θ,|θ|θ=1,使得ψ(z)=φ(θz).这一结果是完全不同于Hardy空间与Bergman空间上的相应结果.     

单位球上不同Bergman空间之间小Hankel算子的本性模

本文利用指标φ的Berezin变换给出了小Hankel算子hφ:Ap(B)→Aq(B)(1 p∞,1q∞,p q)的本性模估计C1lim sup|a|→1-|Vφ(a)|∥hφ∥e,Ap(B)→Aq(B)C2lim sup|a|→1-|Vφ(a)|,∫其中Vφ(a)=∫B{k2(1+1/p-1/q)(w,a)1}/K1+1/p-1/q(a,a)φ(w)dν(w),C1和C2是常数.作为应用,本文给出了此类算子有界当且仅当supa∈B|Vφ(a)|∞,而此类算子是紧的当且仅当lim sup|a|→1-|Vφ(a)|=0.     

Reinhardt域上一类推广的Roper-Suffridge算子

研究一类推广的Roper-Suffridge算子F(z)=(f(z_1)+f′(z_1)∑_(k=2)~nakz_k~pk,f′(z)1)(~1/p2)z_2,…,f′(z_1)~(1/pn)z_n)′,证明该算子在复欧氏空间中的Reinhardt域Ω_(n,p2,%…,pn)={z=(z_1,…,z_n)∈C~n:|z_|~2+∑_(k=2)~n|zk|~(pk)1,Pk∈N~+,k=2,…,n}上分别保持α次的殆β型螺形性,α次的β型螺形性及强β型螺形性.     

从混合模空间到Zygmund-型空间的一些积型算子

设D={z∈C:|z|1}是复平面上的单位圆盘,H(D)表示D上的所有解析函数的集合,ψ_1,ψ_2∈H(D),n是一个非负整数,φ是D到D的一个解析自映射,μ是一个权函数.研究从混合模空间到Zygmund-型空间的积型算子T_(ψ_1,ψ_2,φ)~n的有界性和紧性特征,其中T_(ψ_1,ψ_2,φ)~nf(z)=ψ_1(z)f~((n))(φ(z))+ψ_2(z)f~((n+1))(φ(z)),f∈H(D).     

THE ASYMPTOTIC BEHAVIOUR OF ANALYTIC FUNCTIONS

AIn this paper, the author obtains the following results:(1) If Taylor coeffiients of a function satisfy the conditions:(i),(ii),(iii)A_k=O(1/k) the for any h>0 the function φ(z)=exp{w(z)} satisfies the asymptotic equality the case h>1/2 was proved by Milin.(2) If f(z)=z α_2z~2 …∈S~* and,then for λ>1/2     

Sharp Inequalities for BMO Functions

The purpose of the paper is to study sharp weak-type bounds for functions of bounded mean oscillation. Let 0 p ∞ be a fixed number and let I be an interval contained in R. The author shows that for any φ : I → R and any subset E I of positive measure,For each p, the constant on the right-hand side is the best possible. The proof rests on the explicit evaluation of the associated Bellman function. The result is a complement of the earlier works of Slavin, Vasyunin and Volberg concerning weak-type, L ~p and exponential bounds for the BMO class.     

Partial sums and the radius problem for some class of conformal mappings

Let $|\frac{{s_n (z)}} {{f(z)}} - 1| $|\frac{{s_n (z)}} {{f(z)}} - 1| when f ∈ $\left| {f'(z)\left( {\frac{z} {{f(z)}}} \right)^2 - 1} \right| < 1$\left| {f'(z)\left( {\frac{z} {{f(z)}}} \right)^2 - 1} \right| < 1     

${\mbox{\boldmath $R$}}^N$上奇异非线性多调和方程的正整体解

本文研究形如△((△nu)(p-1) )=f(|x|,u,|(?)u|)u-β,x∈RN的奇异非线性多调和方程在RN上的正整体解,此处P>1,β≥0是常数,n是自然数,f:R × R ×R →R 是一个连续函数, ξδ*:=sign(ξ)·|ξ|δ,,ξ∈R,δ>0,给出了该类方程具有无穷多个其渐进阶刚好为|x|2n的正整体解的充分条件与必要条件.这些结论可以推广到更一般的方程.     

奇异非线性$p-$调和方程的一类正整体解

设p>1,β≥0是常数, n是自然数, 是一个连续函数.本文研究形如的奇异非线性p-调和方程的正整体解,给出了该类方程具有无穷多个其渐近阶刚好为|x|(2n-2)(当|x|→∞时)的径向对称的正整体解的若干充分条件.     

Regularity Results for a Nonlinear Elliptic-Parabolic System with Oscillating Coefficients

In this paper we study the initial boundary value problem for the system $\mbox{div}(\sigma(u)\nabla\varphi)=0,$ $ u_t-\Delta u=\sigma(u)|\nabla\varphi|^2$. This problem is known as the thermistor problem which models the electrical heating of conductors. Our assumptions on $\sigma(u)$ leave open the possibility that $\liminf_{u\rightarrow\infty}\sigma(u)=0$, while $\limsup_{u\rightarrow\infty}\sigma(u)$ is large. This means that $\sigma(u)$ can oscillate wildly between $0$ and a large positive number as $u\rightarrow \infty$. Thus our degeneracy is fundamentally different from the one that is present in porous medium type of equations. We obtain a weak solution $(u, \varphi)$ with $|\nabla \varphi|, |\nabla u|\in L^\infty$ by first establishing a uniform upper bound for $e^{\varepsilon u}$ for some small $\varepsilon$. This leads to an inequality in $\nabla\varphi$, from which the regularity result follows. This approach enables us to avoid first proving the Hölder continuity of $\varphi$ in the space variables, which would have required that the elliptic coefficient $\sigma(u)$ be an $A_2$ weight. As it is known, the latter implies that $\ln\sigma(u)$ is "nearly bounded''.     

共形双曲度量的孤立奇点

Nitsche证明了共形双曲度量的孤立奇点要么是锥奇点,要么是尖奇点,二者必其一(Nitsche J.über die isolierten singularit?ten der L?sungen von△u=e~u [J]. Math Z, 1957, 68(3):316-324.).本文利用展开映射证明了在孤立奇点附近存在复坐标z,使得度量要么为(4α~2|z|~(2α-2))/((1-|z|~(2α))~2)|dz|~2,其中α 0,要么为|z|~(-2)(ln|z|)~(-2)|dz|~2.     

具位势项的快扩散方程的第二临界指标

This paper considers a fast diffusion equation with potential ut= um V (x)um+upin Rn×(0,T), where 1 2αm+n< m ≤ 1, p > 1, n ≥ 2, V (x) ～ω|x|2with ω≥ 0 as |x| →∞,and α is the positive root of αm(αm + n 2) ω = 0. The critical Fujita exponent was determined as pc= m +2αm+nin a previous paper of the authors. In the present paper,we establish the second critical exponent to identify the global and non-global solutions in their co-existence parameter region p > pcvia the critical decay rates of the initial data.With u0(x) ～ |x| aas |x| →∞, it is shown that the second critical exponent a =2p m,independent of the potential parameter ω, is quite different from the situation for the critical exponent pc.     

BERGMAN TYPE OPERATOR ON MIXED NORM SPACES WITH APPLICATIONS

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On the Springer''s Conjecture of the Coefficients of Univalent Meromorphic Functions

Let $\sigma$ denote the family of univalent functions $\[F(z) = z + \sum\limits_{n = 1}^\infty {\frac{{{b_n}}}{{{z^n}}}} \]$ in l< |z| <\infty if G(w) is the inverse of a function $F(z) \in \sigma ^'$, the expansion of G(w) in some neighborhood of w=\infty is $\[G(w) = w - \sum\limits_{n = 1}^\infty {\frac{{{B_n}}}{{{w^n}}}} \]$ It is well known that |B_1|\leq 1 for any F(z) \in \sigma ^'. Springer^[1] proved that | B_3| \leq 1 and conjectured that $\[|{B_{2n - 1}}| \le \frac{{(2n - 2)!}}{{n!(n - 1)!}}{\rm{ }}(n = 3,4, \cdots )\]$ (1) Kubota^[2] proved (1) for n=3, 4, 5. Schober^[3] proved (1) for n = 6, 7. Ren Fuyao[4,5] has verified (1) for n=6, 7, 8. In this article we are going to verify (1) for n=9.