LF拟仿紧空间

本文定义了ＬＦ拟仿紧空间的概念，用半内部等概念给出ＬＦ拟仿紧空间的刻划，作者讨论了ＬＦ拟仿紧空间的半正则化，Ｌ－好的推广等问题，得到一系列结果，还在几乎Ｈｕｔｔｏｎ正则ＬＦ拓扑空间中讨论了ＬＦ拟仿紧空间的进一步的性质。     

拟仿紧性与乘积空间

本文证明了在V=L假定下,所有正规局部紧拟仿紧空间是仿紧的．并证明了正则拟仿紧性在有限 对一闭映射下是逆保持的．还研究了狭义拟仿紧性的有限乘积和逆极限定理．     

拟仿紧性与乘积空间

本文证明了在V=L假定下,所有正规局部紧拟仿紧空间是仿紧的.并证明了正则拟仿紧性在有限对一闭映射下是逆保持的.还研究了狭义拟仿紧性的有限乘积和逆极限定理.     

关于狭义拟仿紧空间

本文研究了狭义拟仿紧空间的两个因子的乘积和逆序列的极限的性质.还肯定地回答了刘应明在[1,2]中提出的一个问题.     

关于狭义拟仿紧空间

本文研究了狭义拟仿紧空间的两个因子的乘积和逆序列的极限的性质,还肯定地回答了刘应明在[1,2]中提出的一个问题。     

正规狭义拟仿紧的乘积性质

本文主要证明了如下一些结果(1)设     

正规狭义拟仿紧的乘积性质

本文主要证明了如下一些结果：（１）设Ｘ＝Ｌｉｍ并且每个投射πσ是开满映射,如果Ｘ是－仿紧的且每个 Ｘσ是正规狭义拟仿紧的,则 Ｘ是正规狭义拟仿紧的;如果 Ｘ是遗传－仿紧的且每个 Ｘσ是遗传正规狭义拟仿紧的．则 Ｘ是遗传正规狭义拟仿紧的． （２）如果 Ｘ＝是 －仿紧空间,则Ｘ是正规狭义拟仿紧的当且仅当 是正规狭义拟仿紧的．最后,还给出了诸多覆盖性质的可数乘积的一个等价性命题．     

仿紧性与性质b_1

本文建立关于仿紧性的下列 Alexandroff-urysohn 型特征定理:空间 X 是仿紧的当且仅当 X 的每个良序单调开覆盖有开的局部θ-加细序列.我们还讨论了正紧与点星形正紧性(或离散正紧性)的等价性.     

半群的拟紧性和不可约性

利用算子半群生成元的边界扰动方法,给出了Banach格上C0半群的拟紧性和不可约性的充分条件.并利用该结果对一串联可修复系统的拟紧性和不可约性进行了研究.     

L—Fuzzy拓扑空间的仿紧性和强仿紧性

仿紧性是分明拓扑学中的一个重要概念,如何合理定义LF拓扑中的仿紧性是一引人注目的课题。基于良紧性的几何刻划[4],文[3]和文[2]分别引入F拓扑中的局部有限族和仿紧性。文[2]对弱诱导的仿紧空间进行了比较深入的研究。但[2]和[3]的讨论还没有涉及到仿紧性的可乘性、分离性等问题。此外[2]引入了另一种局部有限性质:     

亚紧空间的可数乘积

In this paper,we present that if Y is a hereditarily metacompact space and{Xn:n∈ω}is a countable collection of Cech-scattered metacompact spaces,then the followings are∏equivalent:(1)Y×∏n∈ωXn is metacompact,(2)Y×∏n∈ωXn is countable metacompact,(3)Y×n∈ωXn is orthocompact.Thereby,this result generalizes Theorem 5.4 in[Tanaka,Tsukuba.J.Math.,1993,17:565–587].In addition,we obtain that if Y is a hereditarilyσ-metacompact space and{Xn:n∈ω∏}is a countable collection of Cech-scatteredσ-metacompact spaces,then the product Y×n∈ωXn isσ-metacompact.     

The relationship between fragmentable spaces and class spaces

In this note, we show that each fragmentable space introduced by Jayne and Rogers in 1985 is of class which was introduced by Kenderov in 1984. Our example shows that a space which is of class may not be a fragmentable space.

     

-compactness and automatic continuity in ultrametric spaces of bounded continuous functions

In this paper (weakly) separating maps between spaces of bounded continuous functions over a nonarchimedean field are studied. It is proven that the behaviour of these maps when is not locally compact is very different from the case of real- or complex-valued functions: in general, for -compact spaces and , the existence of a (weakly) separating additive map implies that and are homeomorphic, whereas when dealing with real-valued functions, this result is in general false, and we can just deduce the existence of a homeomorphism between the Stone-Cech compactifications of and . Finally, we also describe the general form of bijective weakly separating linear maps and deduce some automatic continuity results.

     

Variational representations of Varadhan functionals

Motivated by the theory of large deviations, we introduce a class of non-negative non-linear functionals that have a variational ``rate function" representation.

     

A separable non-remainder of

We prove that there is a compact separable continuum that (consistently) is not a remainder of the real line.

     

The -PIP and integrability of a single function

Two examples are given that answer in the negative the following question asked by E. M. Bator: If is bounded and weakly measurable and for each in there is a bounded sequence in such that a.e., does it follow that is Pettis integrable?

     

Complemented isometric copies of in dual Banach spaces

Let be a real or complex Banach space and . Then contains a -complemented, isometric copy of if and only if contains a -complemented, isometric copy of if and only if contains a subspace -asymptotic to .

     

Asymptotic properties of Banach spaces under renormings

It is shown that a separable Banach space can be given an equivalent norm with the following properties: If is relatively weakly compact and , then converges in norm. This yields a characterization of reflexivity once proposed by V.D. Milman. In addition it is shown that some spreading model of a sequence in is 1-equivalent to the unit vector basis of (respectively, ) implies that contains an isomorph of (respectively, ).

     

Non-Negative Integer Matrix Representations of a $\mathbb{Z}_{+}$-Ring

The $\mathbb{Z}_{+}$-ring is an important invariant in the theory of tensor category. In this paper, by using matrix method, we describe all irreducible $\mathbb{Z}_{+}$-modules over a $\mathbb{Z}_{+}$-ring $\mathcal{A}$, where $\mathcal{A}$ is a commutative ring with a $\mathbb{Z}_{+}$-basis{$1$, $x$, $y$, $xy$} and relations: $$ x^{2}=1,\;\;\;\;\; y^{2}=1+x+xy.$$We prove that when the rank of $\mathbb{Z}_{+}$-module $n\geq5$, there does not exist irreducible $\mathbb{Z}_{+}$-modules and when the rank $n\leq4$, there exists finite inequivalent irreducible $\mathbb{Z}_{+}$-modules, the number of which is respectively 1, 3, 3, 2 when the rank runs from 1 to 4.     

The optimality of James's distortion theorems

A renorming of , explored here in detail, shows that the copies of produced in the proof of the Kadec-Pelczynski theorem inside nonreflexive subspaces of cannot be produced inside general nonreflexive spaces that contain copies of . Put differently, James's distortion theorem producing one-plus-epsilon-isomorphic copies of inside any isomorphic copy of is, in a certain sense, optimal. A similar renorming of shows that James's distortion theorem for is likewise optimal.