局部可数集族、局部有限集族与Alexandroff问题

本文引进分层强ｓ－映射和分层强紧映射建立具有σ－局部可数网、具有σ－局部可数ｋ－网、具有σ－局部可数基的正则空间以及σ－空间、－空间、ｇ－可度量空间和确定的度量空间之间的联系．这些都是对Ａｌｅｘａｎｄｒｏｆｆ问题的回答．     

具有σ—局部可数弱基的空间

本文利用msss-映射,建立了具有σ－局部可数cs-网的空间和具有σ－局部可数弱基的空间与度量空间的关系,这是对Alexandroff的部分的肯定回答。     

关于σ-局部可数映射(英文)

借助σ-局部可数映射,建立了一些具有σ-局部可数网的空间与度量空间之间的关系。     

σ -局部有限集族与度量空间的σ -映象

利用σ-映射建立了具有σ-局部有限cs-网、σ-局部有限cs*-网、σ-局部有限序列邻域网、σ-局部有限序列开网的空间与度量空间确定的σ-映象之间的联系.     

关于msss-映射

本文证明了如下结果:(1)T₃空间X具有σ-局部可数cs^*-网当且仅当X是某-度量空间的序列复盖msss-映象;(2)T₃空间X具有σ-局部可数cs-网当且仅当X是某一度量空间的强序列复盖msss-映象.     

关于R-商、ss-映射

本文借助于R-商、ss-映射建立具有局部可数k-网的k_R-空间(具有由紧子集组成的局部可数k-网的k_R-空间)和度量空间(局部紧度量空间)之间的联系。     

关于局部可数网与ss映射

本文建立了度量空间在几类序列覆盖ss映射下象空间的特征,讨论了局部可数集族与局部可数基（弱基）之间的相互关系,特别地证明了几类具有特定性质的局部可数网的正则空间与度量空间的几类序列覆盖ss映象之间相互等价,回答了Tanaka提出的一个问题．     

关于局部紧空间的闭Lindelof映象

本文给出了两类局部紧空间闭Ｌ（Ｌｉｎｄｅｌｏｆ）映象的内部特征,证明了空间Ｘ是仿紧局部紧空间的闭Ｌ映象当且发Ｘ是具有σ－局部有限ｋ系的ｋ空间,由此得到在ｋ′空间类中,偏紧局部紧空间的闭Ｌ映象等价于偏紧局部紧空间的商ＳＬＪ央象,同时不证明了空间Ｘ是局部紧度量空间的闭Ｌ映象当且Ｘ是具有σ－局部有限紧ｋ网的Ｆｒｅｃｈｅｔ空间。     

σ-局部有限网与mssc-映射

建立了若干类具有σ-局部有限网的拓扑空间与度量空间的mssc一映象的联系。     

局部可分度量空间闭s映象的注记

该文讨论局部可分度量空间闭s映象的分解定理, 证明了正则的Fréchet空间是局部可分度量空间的闭s映象当且仅当满足如下条件: 具有点可数的cs*网, 第一可数的闭子空间是局部可分的, 且Lindelof的闭子空间是可分的.     

Locally M-Pseudoconvex Topologies on Locally A-Pseudoconvex Algebras

Let (A, T) be a locally A-pseudoconvex algebra over or . We define a new topology m(T) on A which is the weakest among all m-pseudoconvex topologies on A stronger than T. We describe a family of non-homogeneous seminorms on A which defines the topology m(T).     

Locally Well-Dominated and Locally Independent Well-Dominated Graphs

 In this article we present characterizations of locally well-dominated graphs and locally independent well-dominated graphs, and a sufficient condition for a graph to be k-locally independent well-dominated. Using these results we show that the irredundance number, the domination number and the independent domination number can be computed in polynomial time within several classes of graphs, e.g., the class of locally well-dominated graphs. Received: September 13, 2001 Final version received: May 17, 2002 RID="*" ID="*" Supported by the INTAS and the Belarus Government (Project INTAS-BELARUS 97-0093) RID="†" ID="†" Supported by RUTCOR RID="*" ID="*" Supported by the INTAS and the Belarus Government (Project INTAS-BELARUS 97-0093) 05C75, 05C69 Acknowledgments. The authors thank the referees for valuable suggestions.     

Concretely Locally Presentable and Locally Generated Categories

We give concrete versions of the characterizations of locally -presentable (resp. -generated) categories as categories of models of (resp. weakly) -ary limit-theories and of (resp. weakly) -ary essentially algebraic theories. By concrete we mean that starting with a category of -structures, the theories obtained are extensions of the original ones, and the equivalences of categories are concrete isomorphisms. -presentable and -generated objects are also investigated from this viewpoint.     

局部Cauchy列和局部完备性的性质

利用完备化的方法,给出了局部凸分离空间（X,T）中序列{xn}是局部Cauchy列当且仅当存在单调增且趋于正无穷大的正实数列{an},使得min{an,am}（xn-xm）→0（m,n→∞）,并得到局部凸分离空间（X,T）是局部完备的当且仅当X中每个丁局部Cauchy列的绝对凸闭包是丁紧的,以及一些局部完备性的相关性质．     

Locally Tabular $$\ne $$ Locally Finite

We show that for an arbitrary logic being locally tabular is a strictly weaker property than being locally finite. We describe our hunt for a logic that allows us to separate the two properties, revealing weaker and weaker conditions under which they must coincide, and showing how they are intertwined. We single out several classes of logics where the two notions coincide, including logics that are determined by a finite set of finite matrices, selfextensional logics, algebraizable and equivalential logics. Furthermore, we identify a closure property on models of a logic that, in the presence of local tabularity, is equivalent to local finiteness.