拓扑分子格的σ分离性

在拓扑分子格理论中,利用有序闭远域概念引入σi分离性(i=-1,0,1,2,3,4)、σ正则分离性和σ正规分离性等概念.较为系统地研究了这些概念的特征性质、遗传性质和拓扑性质.讨论了σ分离性与Ui-分离性和Ti-分离性之间的相互关系.     

L-Fuzzy保序算子空间的ω-分离性

在L-fuzzy保序算子空间中引进了ω-分离性等概念，系统地讨论了这些概念的性质。得出它们保持了L-fuzzy拓扑空间中的Ti分离性的主要结论，进而说明ω-分离性是R．Lowen的推广．     

L-fuzzy拓扑空间中的包含式正则分离性

本文首先在一般L-fuzzy拓扑空间中引入了包含式正则分离性的概念.其次将包含式正则分离性与点式正则分离性及正则分离性作了比较,讨论了它们之间的相互蕴含关系.最后说明了包含式正则分离性与包含式正规分离性及包含式完全正则分离性之间的协调性.     

LF拓扑空间的E_sT-分离性

为了进一步研究LF拓扑空间的分离性,利用E_s远域将LF拓扑空间的T-分离性的概念进行了推广,即得E_sT-分离性.给出了E_sT-分离性的一些等价刻画,讨论了E_sT-分离性之间的联系及其基本性质(如L-好的推广,E_s同胚不变性等),最后得出了T-分离性与E_sT-分离性的关系.     

LF拓扑空间的正则闭分离性

利用正则闭集概念在LF拓扑空间中引入了正则闭分离性Ti^rc（i=-1，O），次To^rc概念，给出了它们的刻画，证明了正则闭Ti^rc（i=-1，0）分离性、次To^rc分离性为拓扑性质，在LF拓扑空间的半正则化中Ti^rc分离性与Ti分离性是等价的。     

LF拓扑空间的rT-分离性

在利用r闭远域概念引入了rT-分离性的基础上讨论了该分离性的一些等价刻画和基本性质(L-好的推广、LF-r拓扑性质及遗传性等).结果表明它们保持了LF拓扑空间中的T-分离性的主要结果,是LF拓扑空间中的T-分离性的推广.     

L-拓扑空间的次分离性公理

在L-拓扑空间中引入称之为次分离的分离性公理,包括次T1、次T2、次T212、次T3、次T4分离性等。新的分离性公理体系协调性很好,具有预期好的性质,如:具有遗传性和可乘性,是Low en意义下“L-好的推广”,和在次T2空间中分子网收敛在一定意义下唯一等。此外,文中还初步讨论了次分离性与文献中其它分离性的关系。     

拓扑分子格的ST*分离性公理

由半开元、半拓扑概念出发在拓扑分子格中引入 ST* 分离性公理 ,给出它们的刻画 ,推广文 [2 ]中 T* 分离性公理 ,并得到 ST* 分离性与 T* 分离性之间的关系。     

L-fuzzy拓扑空间中关于子基的分离性

在L-fuzzy拓扑空间中引入了关于子基的分离性公理,给出了它们的特征刻画,研究了它们的一系列基本性质,如可遗传性、可积性、L-fuzzy同胚不变性等,并得到了这类新分离性与T分离性是等价的.     

L-Fuzzy拓扑空间的层分离性公理

在一般L-fuzzy拓扑空间中引入一套新的分离性公理。即层分离性公理。并研究其性质．讨论层分离性公理与L-fuzzy拓扑空间中的第一套分离性公理间的关系。表明前者比后者弱且两者有很好的协调性。     

On binormality in non-separable Banach spaces

We study binormality, a separation property of the norm and weak topologies of a Banach space. We show that every Banach space which belongs to a P-class is binormal. We also show that the asplundness of a Banach space is equivalent to a related separation property of its dual space.     

A nonconvex separation property in Banach spaces

We establish, in infinite dimensional Banach space, a nonconvex separation property for general closed sets that is an extension of Hahn-Banach separation theorem. We provide some consequences in optimization, in particular the existence of singular multipliers and show the relation of our property with the extremal principle of Mordukhovich. Received October 1997/Revised version February 1998     

Spaces from pieces IV

We are going to investigate simultaneous extensions of various topological structures (i.e. traces on several subsets at the same time are prescribed), also with separation axioms T₀, T₁, symmetry (in the sense of Part I, § 3), Riesz property, Lodato property. The following questions will be considered: (i) Under what conditions is there an extension? (ii) How can the finest extension be described? (iii) Is there a coarsest extension? (iv) Can we say more about extensions of two structures than in the general case? (v) Assume that certain subfamilies (e.g. the finite ones) can be extended; does the whole family have an extension, too? The general categorial results from Part I will be applied whenever possible (even they are not really needed).     

Strict inductive limits in locally convex cones

We propose a definition for strict inductive limits in locally convex cones. By this definition, we prove that the strict inductive limit of a sequence of locally convex cones with the strict separation property has the same strict separation property. Also we establish that the strict inductive limit of a sequences of separated cones is separated too. Finally we verify barreledness for this strict inductive limit.     

Integro-differential properties of the singular Sturm-Liouville operator

We consider the properties of the positiveness, fractional power, boundedness, and separation of the singular Sturm-Liouville operator in a weighted space depending on the behavior of its coefficients. We derive necessary and sufficient conditions for its positiveness, trace class property, boundedness, and separation.     

More remarks on Souslin properties and tree topologies

We investigate separation properties of ω₁-trees. We show that the property γ of Devlin and Shelah is equivalent to hereditary collectionwise normality. We show that monotone normality and divisibility are both equivalent to orderability. Finally we show that Souslin trees are examples of trees with property γ which are not retractable.     

Iterated function systems of finite type and the weak separation property

We prove that any iterated function system of finite type possesses the weak separation property.

     

Superintuitionistic logics and the projective beth property

It is proved that in superintuitionistic logics, the projective Beth property follows from the Craig interpolation property, but the converse does not hold. A criterion is found which allows us to reduce the problem asking whether the projective Beth property is valid in superintuitionistic logics to suitable properties of varieties of pseudoboolean algebras. It is shown that the principle of variable separation follows from the projective Beth property. On the other hand, the interpolation property in a logic L implies the projective Beth property in Δ(L). Supported by RFFR grants No. 96-01-01552 and No. 99-01-00600. Translated fromAlgebra i Logika, Vol. 38, No. 6, pp. 680–696, November–December, 1999.     

Existentially Complete Nerode Semirings

Let Λ denote the semiring of isols. We characterize existential completeness for Nerode subsemirings of Λ, by means of a purely isol-theoretic “Σ₁ separation property”. (A “concrete” characterization that is not Λ-theoretic is well known: the existentially complete Nerode semirings are the ones that are isomorphic to Σ₁ ultrapowers.) Our characterization is purely isol-theoretic in that it is formulated entirely in terms of the extensions to Λ of the Σ₁ subsets of the natural numbers. Advantage is taken of a special kind of isol first conjectured to exist by Ellentuck and first proven to exist by Barback (unpublished). In addition, we strengthen the negative part of [13] by showing that existential completeness is not secured, for a given Nerode semiring, by either (i) a certain “functional closure” property for the extensions of partial recursive functions or (ii) the property of “pulling in” some portion of each partial recursive fiber; these latter results are perhaps a little surprising.     

Geometric characterizations of Gromov hyperbolicity

We prove the equivalence of three different geometric properties of metric-measure spaces with controlled geometry. The first property is the Gromov hyperbolicity of the quasihyperbolic metric. The second is a slice condition and the third is a combination of the Gehring–Hayman property and a separation condition. Mathematics Subject Classification (1991) 30F45