单位圆盘上再生■[z]-模的刚性

主要研究单位开圆盘上■[z]-模的子模的刚性.证明了空间■_α(0<α<1)的子模具有刚性,这和Hardy空间的情况截然不同.本文还证明了Dirichlet空间的一类子模也具有刚性.     

分数次积分在局部Hardy空间上的有界性质

证明了当0<αn/(n-α)时,分数次积分Iα是局部Hardy空间hp(Rn)到空间hp(Rn)+Lq(Rn)的一个线性映射.     

关于随机赋范模中最佳逼近的一个注记

证明了随机赋范模中一个点是其任一子模的依概率范数的弱最佳逼近点当且仅当它是该子模的依概率范数的最佳逼近点,亦当且仅当该点是该子模的依随机范数的最佳逼近点.利用这些关系我们可以借助于随机赋范模的最近进展获得许多概率赋范空间中的新的最佳逼近定理.     

(α,δ)-弱刚性环上的Ore扩张

本文研究（α,δ）-弱刚性环上的Ore扩张环R[x;α,δ]的弱对称性、弱zip性、幂零p.p.性和幂零Baer性.利用对多项式的逐项分析的方法,证明了如果R是（α,δ）-弱刚性环和半交换环,则Ore扩张环R[x;α,δ]是弱对称的（弱zip的,幂零p.p.的,幂零Baer的）当且仅当R是弱对称的（弱zip的,幂零p.p.的,幂零Baer的）.这些结果统一和扩展了前面已有的相关结论.     

具有次亚B性质的ωα＋1－紧T1空间是ωα－Lindel?f空间

在本文中，我们证明了具有次亚Ｂ性质的ω_α＋1-紧Ｔ₁空间是ω_α－Ｌｉｎｄｅｌ?ｆ空间，此结果改进并推广了［１］中的主要结果。     

加权Bergman空间上Toeplitz与Hankel算子紧性的一个新特征

本文研究加权Ｂｅｒｇｍａｎ空间Ａ^（ｐ,α）（Ｂ）（ｐ＞１）上Ｔｏｅｐｌｉｔｚ与Ｈａｎｋｅｌ算子的紧性．证明了符号属于Ｌ^∞（Ｂ）的Ｔｏｅｐｌｉｔｚ与Ｈａｎｋｅｌ算子的紧性与作用空间Ａ^ｐ,α（Ｂ）无关     

斜三角矩阵环的强可逆性和弱刚性

设σ是环R的一个自同态,δ是R的一个σ-导子.研究斜三角矩阵环T_n(R,α)的强可逆性和(σ,δ)-弱刚性,证明了1)若α是环R的一个刚性自同态,则环R是强可逆环当且仅当T_n(R,α)是强可逆环;2)若α和σ都是环R的刚性自同态,ασ=σα,且R是δ-弱刚性环,则R是(σ,δ)-弱刚性环当且仅当T_n(R,α)是(σ,δ)-弱刚性环.     

复射影空间中极小曲面的整体刚性定理

本文主要研究复射影空间中的紧复曲线以及全实极小曲面的整体刚性问题.定义|A|2为复射影空间中紧复曲线∑的第二基本形式的模长平方.我们证明了如果∫∑|A|2dμ＜1/378π,那么∑是全测地的.对于全实极小曲面,我们也得到了类似的刚性定理.更一般地,我们证明了复射影空间中关于极小曲面的整体刚性定理.     

作用在加权Bergman空间上的无穷维Hilbert张量

本文首先介绍了一些基本的定义和事实,它们将用于证明我们的主要结果.其次,我们给出了Hilbert张量算子H的定义,并借助Song和Qi文章中的证明技巧,给出了一些引理,这些引理表明Hilbert张量算子H是良性定义的.此外,本文引入了Song和Qi给出的Hilbert张量算子的积分形式.随后,本文刻画了m阶无穷维Hilbert张量(超矩阵,即Hilbert张量算子),从加权Bergman空间A_α⁽p(m-1))(α>-1,α+2

β^q(β>-1,0 H,F_H是由Hilbert张量算子H诱导出的正齐次算子,借助Hilbert张量算子H在加权Bergman空间上的有界性及齐次性,文章证明了T_H从加权Bergman空间A_α⁽p(m-1))(α>1,α+2

相似文献   

半平面中解析函数的积分表示及在逼近中的应用

在该文中, 作者证明了满足一定增长性条件的右半平面上的解析函数可以由它在边界上的积分和其加权Blaschke乘积的和表示, 作为应用, 作者还考虑了指数多项式在实数轴上加权 Banach 空间C_α 中的完备性.     

The core operator and congruent submodules

The Hardy spaces H²(D²) can be conveniently viewed as a module over the polynomial ring C[z₁,z₂]. Submodules of H²(D²) have connections with many areas of study in operator theory. A large amount of research has been carried out striving to understand the structure of submodules under certain equivalence relations. Unitary equivalence is a well-known equivalence relation in set of submodules. However, the rigidity phenomenon discovered in [Douglas et al., Algebraic reduction and rigidity for Hilbert modules, Amer. J. Math. 117 (1) (1995) 75-92] and some other related papers suggests that unitary equivalence, being extremely sensitive to perturbations of zero sets, lacks the flexibility one might need for a classification of submodules. In this paper, we suggest an alternative equivalence relation, namely congruence. The idea is motivated by a symmetry and stability property that the core operator possesses. The congruence relation effectively classifies the submodules with a finite rank core operator. Near the end of the paper, we point out an essential connection of the core operator with operator model theory.     

On negative limit sets for one-dimensional dynamics

In this paper we study the structure of negative limit sets of maps on the unit interval. We prove that every α-limit set is an ω-limit set, while the converse is not true in general. Surprisingly, it may happen that the space of all α-limit sets of interval maps is not closed in the Hausdorff metric (and thus some ω-limit sets are never obtained as α-limit sets). Moreover, we prove that the set of all recurrent points is closed if and only if the space of all α-limit sets is closed.     

Quotient finite dimensional modules with acc on subdirectly irreducible submodules are noetherian

A right R-module M is (Goldie) finite dimensional (= f.d.) if M contains no infinite direct sums of submodules.M is quotient f.d. (= q.f.d.) if M/K is f.d. for all submodules K.A submodule I of M is subdirectly irreducible (= SDI) if V is the intersection of all submodules S _α of M that properly contain I, then V ≠ I, equivalentlyM/I has simple essential socle V/I. A theorem of Shock [74] states that a q.f.d. right module M is Noether-ian iff every proper submodule of M is contained in a maximal submodule. Camillo [77], proved a companion theorem: M is q.f.d. iff every submodule A ≠ 0 contains a finitely generated (= f.g) submodule S such that A/S has no maximal submodules. Using these two results, and an idea of Camillo [75], we prove the theorem stated in the title.     

Existence and convergence theorems for generalized hybrid mappings in uniformly convex metric spaces

In this paper, we show a relationship between strictly convexity of type (I) and (II) defined by Takahashi and Talman, and we prove that any uniformly convex metric space is strictly convex of type (II). Continuity of the convex structure is also shown on a compact domain. Then, we prove the existence of a minimum point of a convex, lower semicontinuous and d-coercive function defined on a nonempty closed convex subset of a complete uniformly convex metric space. By using this property, we prove fixed point theorems for (α, β)-generalized hybrid mappings in uniformly convex metric spaces. Using this result, we also obtain a common fixed point theorem for a countable commutative family of (α, β)-generalized hybrid mappings in uniformly convex metric spaces. Finally, we establish strong convergence of a Mann type iteration to a fixed point of (α, β)-generalized hybrid mapping in a uniformly convex metric space without assuming continuity of convex structure. Our results can be applied to obtain the existence and convergence theorems for (α, β)-generalized hybrid mappings in Hilbert spaces, uniformly convex Banach spaces and CAT(0) spaces.     

Hypersurfaces of the hyperbolic space with constant scalar curvature

We classify hypersurfaces of the hyperbolic space ?ⁿ⁺¹(c) with constant scalar curvature and with two distinct principal curvatures. Moreover, we prove that if Mⁿ is a complete hypersurfaces with constant scalar curvature n(n ? 1) R and with two distinct principal curvatures such that the multiplicity of one of the principal curvatures is n? 1, then R ≥ c. Additionally, we prove two rigidity theorems for such hypersurfaces.     

Some Bernstein-type rigidity theorems

We prove some Bernstein-type rigidity theorems for complete submanifolds in a Euclidean space and space-like submanifolds of a Lorentzian space. In particular, we obtain a Bernstein rigidity theorem for complete minimal submanifolds of arbitrary codimension in Euclidean space.     

On Einstein Matsumoto metrics

We study a special class of Finsler metrics,namely,Matsumoto metrics F=α2α-β,whereαis a Riemannian metric andβis a 1-form on a manifold M.We prove that F is a(weak)Einstein metric if and only ifαis Ricci flat andβis a parallel 1-form with respect toα.In this case,F is Ricci flat and Berwaldian.As an application,we determine the local structure and prove the 3-dimensional rigidity theorem for a(weak)Einstein Matsumoto metric.     

Near-Rings and Partitioned Groups

Over a commutative ring R with identity, free modules M with 2 distinguished submodules are studied. The category Rep₂R of such objects M have the obvious morphisms between them, which are homomorphisms between .R-modules preserving the distinguished submodules. The endo-morphisms for each M constitute a subalgebra End_RM of the algebra End_RM and the readability of λ-generated R-algebras A as End_RM is considered for cardinals λ. Despite the fact that 4 is the minimal number of distinguished submodules for realizing any algebra over a field il, we are able to prove a similar result in Rep₂R for many rings R including R = Z and algebras which are cotorsion-free. Several examples illustrate the boarder line of our main result. The main theorem is applied for constructing Butler groups in [11]     

On the metric properties of multimodal interval maps and <Emphasis Type="Italic">C</Emphasis><Superscript>2</Superscript> density of Axiom A

In this paper, we shall prove that Axiom A maps are dense in the space of C² interval maps (endowed with the C² topology). As a step of the proof, we shall prove real and complex a priori bounds for (first return maps to certain small neighborhoods of the critical points of) real analytic multimodal interval maps with non-degenerate critical points. We shall also discuss rigidity for interval maps without large bounds. Mathematics Subject Classification (2000) Primary 37E05; Secondary 37F25     

Flows, fixed points and rigidity for Kleinian groups

The main application of the techniques developed in this paper is to prove a relative version of Mostow rigidity, called pattern rigidity. For a cocompact group G, by a G-invariant pattern we mean a G-invariant collection of closed proper subsets of the boundary of hyperbolic space which is discrete in the space of compact subsets minus singletons. Such a pattern arises for example as the collection of translates of limit sets of finitely many infinite index quasiconvex subgroups of G. We prove that (in dimension at least three) for G ₁, G ₂ cocompact Kleinian groups, any quasiconformal map pairing a G ₁-invariant pattern to a G ₂-invariant pattern must be conformal. This generalizes a previous result of Schwartz who proved rigidity in the case of limit sets of cyclic subgroups, and Biswas and Mj (Pattern rigidity in hyperbolic spaces: duality and pd subgroups, arxiv:math.GT/08094449, 2008) who proved rigidity for Poincare Duality subgroups. Pattern rigidity is a consequence of the study conducted in this paper of the closed group of homeomorphisms of the boundary of real hyperbolic space generated by a cocompact Kleinian group G ₁ and a quasiconformal conjugate h ^?1 G ₂ h of a cocompact group G ₂. We show that if the conjugacy h is not conformal then this group contains a flow, i.e. a non-trivial one parameter subgroup. Mostow rigidity is an immediate consequence.