Dye’s theorem in the almost continuous category

Suppose X and Y are Polish spaces with non-atomic Borel probability measures μ and ν and suppose that T and S are ergodic measure-preserving homeomorphisms of (X, μ) and (Y, ν). Then there are invariant G _δ subsets X′ ⊂ X and Y′ ⊂ Y of full measure and a homeomorphism ϕ: X′ → Y′ which maps μ|X′ to ν|Y′ and maps T-orbits onto S-orbits. We also deal with the case where T and S preserve infinite invariant measures.     

The variety of Jordan algebras determined by the identity (xy)(zt) ≡ 0 has almost polynomial growth

We prove that, in the case of ground field of characteristic zero, the variety cited in the title has almost polynomial growth. We construct an algebra generating this variety and completely describe the structure of the multilinear part of the variety as a module of the symmetric group.     

(ω)性质的判定

利用新定义的谱集,刻画了Hilbert空间上有界线性算子满足(ω_1)性质和(ω)性质的等价条件.另外,利用该谱集,对算子函数的(ω)性质进行了判定.     

On positive almost weak* Dunford–Pettis operators

In this paper, we introduce the class of almost weak* Dunford–Pettis operators and give a characterization of this class of operators. We study its relation with the classes of weak* Dunford–Pettis operators and almost Dunford–Pettis operators, and its relation with the closely related classes of almost limited operators and L-weakly compact operators.     

Favardʼs theorem of piecewise continuous almost periodic functions and its application

In this paper, by constructing Bochner–Fejér polynomials for piecewise continuous almost periodic functions (PCAP, for short), the authors establish Favard?s theorem of PCAP functions, which illustrates when the primitive function of PCAP function is a PCAP function. As its application, combining coincidence degree theory, we consider the existence of PCAP solution of impulsive single population model with hereditary effects. To our best knowledge, it is the first time when coincidence degree theory is used to study the existence of PCAP solution of impulsive differential equation.     

A Note on Property(ω)

In this note we study the property(ω),a variant of Weyl's theorem introduced by Rakoevic,by means of the new spectrum.We establish for a bounded linear operator defined on a Banach space a necessary and sufficient condition for which both property(ω) and approximate Weyl's theorem hold.As a consequence of the main result,we study the property(ω) and approximate Weyl's theorem for a class of operators which we call the λ-weak-H(p) operators.     

Lω-空间的ω-Lindel(o)f性质

在Lω-空间中引入ω-Lindel(o)f性质和ω-Lindel(o)f空间等概念,给出了其等价刻画,并证明它保持L-拓扑空间中许多良好的性质,如闭遗传性、L-好的推广、被连续的L值Zadeh型函数所保持.此外,引入了ω-紧性的概念,研究了其若干性质.     

Property(ω) and Its Perturbations

A Hilbert space operator T is said to have property(ω1) if σa(T)\σaw(T) ? π00(T), where σa(T) and σaw(T) denote the approximate point spectrum and the Weyl essential approximate point spectrum of T respectively, and π00(T) = {λ∈ iso σ(T), 0 dim N(T- λI) ∞}. If σa(T)\σaw(T) = π00(T), we say T satisfies property(ω). In this note, we investigate the stability of the property(ω1) and the property(ω) under compact perturbations, and we characterize those operators for which the property(ω1) and the property(ω) are stable under compact perturbations.     

Property (ω) and Its Perturbations

In the note,we establish for a bounded linear operator defined on a Hilbert space the necessary and sufficient conditions for the stability of property(ω) by means of the variant of the essential approximate point spectrum and the induced spectrum of consistency in Fredholm and index.In addition,the stability of property(ω) for H(P) operators is considered.     

A closed symplectic four-manifold has almost Kähler metrics of negative scalar curvature

We show that any closed symplectic four-dimensional manifold (M, ω) admits an almost Kähler metric of negative scalar curvature compatible with ω.     

Lω-空间的拟ω-Lindel(o)f性

在Lω-空间中引入拟ω-Lindel(o)f性的概念,讨论拟ω-Lindel(o)f性的一些基本性质,给出拟ω-Lindel(o)f性的几个等价刻画.     

算子矩阵的性质(gω)

设M_R=(T R O S)是定义在Banach空间X⊕Y上的2×2上三角算子矩阵,则T和S满足性质(gw)(或性质(gb))推不出M_R满足性质(gw)(或性质(gb)),即使R=0.文章主要利用局部谱理论的知识,研究了Banach空间上2×2上三角算子矩阵在什么情况下满足性质(gb)和性质(gw).     

广义(ω)性质的一个注记

通过定义新的谱集,研究了Weyl定理的一个变形—广义(w)性质,给出了Banach空间上有界线性算子满足广义(w)性质的充要条件.同时,利用所得的主要结论,我们研究了广义(w)性质的摄动.     

Strongly almost (<Emphasis Type="Italic">ω, λ, q</Emphasis>)-summable sequences

The purpose of this paper is to introduce the spaces of sequences that are strongly almost (ω, λ, q)-summable with respect to a modulus function. We give some relations related to these sequence spaces. It is also shown that if a sequence is strongly (ω, λ, q)-summable with respect to a modulus function, then it is S(λ _q )-statistically convergent.     

(ω)性质及Weyl型定理

(ω)性质是Rakocevic给出的Weyl定理的一种变化.本文通过定义新的谱集,给出了有界线性算子同时满足(ω)性质和a-Weyl定理的充要条件.同时,利用所得的主要结论,研究了H(p)算子的(ω)性质.     

An ‘almost all versus no’ dichotomy in homogeneous dynamics and Diophantine approximation

Let Y ₀ be a not very well approximable m × n matrix, and let \({\mathcal {M}}\) be a connected analytic submanifold in the space of m × n matrices containing Y ₀. Then almost all \({Y \in \mathcal {M}}\) are not very well approximable. This and other similar statements are cast in terms of properties of certain orbits on homogeneous spaces and deduced from quantitative nondivergence estimates for‘quasi-polynomial’ flows on the space of lattices.     

关于E_ω-投射模和E_ω-内射模(英文)

左R-模M称为Eω-内射模,如果对环R中任意的ω阶Euclid理想I来说,任何R-模同态能够拓展为R-模同态。左R-模M称为Eω-投射模,若对环R中任意的ω阶Euclid理想I和任何R-模同态f∈HomR(M,R/I),存在R-模同态g∈HomR(M,R)使得f=πg,其中π是自然同态。本文证明P和Q均是Eω-投射模当且仅当PQ是Eω-投射模。进而,又证明了每一个左R-模是Eω-投射的当且仅当每一个左R-模是Eω-内射。     

广义(ω)性质及亚循环算子

研究了Weyl定理的一种变化形式:广义$(\omega)$性质; 给出了广义$(\omega)$性质成立的充要条件.同时, 广义$(\omega)$性质及算子的亚(超)循环性之间的关系得到了研究.