关于紧算子的Orlicz-Pettis型定理

设X是桶空间,Y是序列完备的局部凸空间.本文证明了,由X到Y的紧算子组成的算子级数,其在弱算子拓扑下和一致算子拓扑下的子级数收敛是一致的,当且仅当(X’,β(X’,X))不拓扑同胚地包含CO;同时证明了,N’中σ(X’,X)-子级数收敛级数是β(X’;X)-子级数收敛的,当且仅当(X’,β(X’,X))不拓扑同胚地包含CO.     

Bergman空间L^1a（Ω）上的Toeplitz和Hankel算子

本文讨论了Bergman空间L^1a(Ω)中Toeplitz和Hankel算子的W^*紧性,得到与L^2a(Ω)上T－H算子紧性^[4]类似的某些结果。     

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.     

非共振带阻尼半线性梁方程系统的存在性结果

本文讨论可能带阻尼项的半线性梁方程系统 utt uxxxx But=Au g( t,x,u) h( t,x)的周期边值问题 .借助 L yapunov- Schmidt方法 ,利用 Leray- Schauder不动点定理 ,在一定条件下证明了该系统至少存在一个解     

Weyl型定理的稳定性

称Hilbert空间算子T∈B(H)满足a-Browder定理,如果σ_a(T)\σ_(aw)(T)=π_(00)~a(T),其中σ_a(T)和σ_(aw)(T)分别表示逼近点谱和Weyl本性逼近点谱,π_(00)~a(T)={λ∈isoσ_a(T),0dim N(T-λI)∞}.如果σ_a(T)\σ_(aw)(T)=π_(00)~A(T),称T满足a-Weyl定理.如果对所有的紧算子K,T+K都满足a-Browder定理(a-Weyl定理),则称T关于a-Browder定理(a-Weyl定理)是稳定性的.该文研究了a-Browder定理和a-Weyl定理的稳定性,给出了算子满足a-Browder定理和a-Weyl定理紧扰动的等价刻画.     

JACKSON‘S THEOREM FOR COMPACT GROUPS

In this article we consider the generalized shift operator defined by (Shuf)(g)=∫Gf(tut^-1g)dt on compact group G and by help of this operator we define “Spherical” modulus of continuity.So we prove Stechkin and Jackson type theorems.     

Bergman空间L_a~1(D)上的Toeplitz和Hankel算子

本文讨论了Bergman空间L1a(D)中Toeplitz和Hankel算子的w 紧性 ,得到与L2 a(D)上Toeplitz、Hankel算子紧性类似的某些结果     

Bergman空间上具有无界符号的迹类Toeplitz算子

本文研究了Bergman空间上具有无界符号的迹类Toeplitz算子的问题.利用构造的方法,获得了L2(Un,dA)中的函数φ,φ在Tn中每一点的任何邻域内都是无界的,并且使得Tφ是Bergman空间Lα2(Un,dA)上的迹类算子的结果.     

Banach格上的b-Dunford-Pettis算子

为了进一步研究Banach格上算子的性质,受b-序有界集和Dunford-Pettis集定义的启发,给出了b-Dunford-Pettis算子的定义,研究了该算子与b-AM-紧算子(Dunford-Pettis全连续算子,弱极限算子,序Dunford-Pettis算子)间的关系;利用b-Dunford-Pettis算子与Dunford-Pettis算子的共轭关系,证明了b-Dunford-Pettis算子满足控制性.     

Bergman空间L_a~1(Ω)上的Toeplitz和Hankel算子

本文讨论了 Bergman空间 L1a(Ω )中 Toeplitz和 Hankel算子的 W* 紧性 ,得到与 L2a(Ω )上 T- H算子紧性 [4]类似的某些结果     

带紧扰动的极大单调算子的满射定理

本文利用逼近方法和Ａｌｔｍａｎ不动点定理获得了带扰动的极大单调算子几个满射定理。     

Point-Based Set-Valued Approximations,C -Differential Operators and Applications

In this article, we investigate the point-based set-valued approximation [H. Xu (1999). Set-valued approximation and Newton's methods. Mathematical Programming , 84 , 401-420.] and the C -differential operator [L. Qi (1996). C -Differential operators, C -differentiability and generalized Newton methods, Applied Mathematics Report, AMR96/5, School of Mathematics, The University of New South Wales, Sydney, Australia.] of a vector valued function. Several questions about C -differential operators posed in [L. Qi (1996). C -Differential operators, C -differentiability and generalized Newton methods, Applied Mathematics Report, AMR96/5, School of Mathematics, The University of New South Wales, Sydney, Australia.] are answered. Further, we discuss the application of C -differential operator in nonsmooth optimization. We derive optimality conditions and establish a mean value theorem in terms of convex C -differential operators. Finally, we propose a conceptual algorithm based on the convex C -differential operators.     

An operator-valued Lyapunov theorem

We generalize Lyapunov's convexity theorem for classical (scalar-valued) measures to quantum (operator-valued) measures. In particular, we show that the range of a nonatomic quantum probability measure is a weak^?-closed convex set of quantum effects (positive operators bounded above by the identity operator) under a sufficient condition on the non-injectivity of integration. To prove the operator-valued version of Lyapunov's theorem, we must first define the notions of essentially bounded, essential support, and essential range for quantum random variables (Borel measurable functions from a set to the bounded linear operators acting on a Hilbert space).     

An Example on Operator Ideals

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Reflexivity of Operator Weighted Shifts

ＲｅｆｌｅｘｉｖｉｔｙｏｆＯｐｅｒａｔｏｒＷｅｉｇｈｔｅｄＳｈｉｆｔｓＬｉＪｕｅｘｉａｎ（李觉先）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＬｉａｏｎｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｓｈｅｎｇｙａｎｇ，１１００３６）ＺｈａｏＴｉａｎｘｉａ（赵天霞...     

A Completely Irreducible Compact Perturbation of a Class of Essentially Normal Operators

Ａ　Ｃｏｍｐｌｅｔｅｌｙ　Ｉｒｒｅｄｕｃｉｂｌｅ　Ｃｏｍｐａｃｔ　Ｐｅｒｔｕｒｂａｔｉｏｎ　ｏｆ　ａ　Ｃｌａｓｓ　ｏｆ　Ｅｓｓｅｎｔｉａｌｌｙ　Ｎｏｒｍａｌ　ＯｐｅｒａｔｏｒｓＪｉａｎｇＣｈｕｎｌａｎ（蒋春澜）ＣａｏＧｕａｎｇｆｕ（曹广福）ＳｕｎＳｈ...     

Hyperreflexivity and operator ideals

Suppose (B,β) is an operator ideal, and A is a linear space of operators between Banach spaces X and Y. Modifying the classical notion of hyperreflexivity, we say that A is called B-hyperreflexive if there exists a constant C such that, for any T∈B(X,Y) with α=supβ(qTi)<∞ (the supremum runs over all isometric embeddings i into X, and all quotient maps of Y, satisfying qAi=0), there exists a∈A, for which β(T−a)?Cα. In this paper, we give examples of B-hyperreflexive spaces, as well as of spaces failing this property. In the last section, we apply SE-hyperreflexivity of operator algebras (SE is a regular symmetrically normed operator ideal) to constructing operator spaces with prescribed families of completely bounded maps.     

A Common Generalization to Theorems on Set Systems with <Emphasis Type="Italic">L</Emphasis>-intersections

In this paper, we provide a common generalization to the well-known Erdös–Ko–Rado Theorem, Frankl–Wilson Theorem, Alon–Babai–Suzuki Theorem, and Snevily Theorem on set systems with L-intersections. As a consequence, we derive a result which strengthens substantially the well-known theorem on set systems with k-wise L-intersections by Füredi and Sudakov [J. Combin. Theory, Ser. A, 105, 143–159 (2004)]. We will also derive similar results on L-intersecting families of subspaces of an n-dimensional vector space over a finite field F _q , where q is a prime power.     

Elementary Operators on Standard Operator Algebras

We present a new simple proof of the structural result for elementary operators on standard operator algebras. Using the idea of this short proof we can characterize surjective maps between standard operator algebras having a certain multiplicativity-like property appearing in the abstract definition of elementary operators of length one. In particular, we show that such maps are automatically additive.     

Elementary Operators on Standard Operator Algebras

We present a new simple proof of the structural result for elementary operators on standard operator algebras. Using the idea of this short proof we can characterize surjective maps between standard operator algebras having a certain multiplicativity-like property appearing in the abstract definition of elementary operators of length one. In particular, we show that such maps are automatically additive.