关于紧连续L-domain的一个刻画定理

本文从函数空间的Isbell拓扑以及ω-连续性两方面给出了紧连续L-domain的刻画定理．其主要结果是：连续L-domain是Lawson紧的当且仅当函数空间[L→L]的Scott拓扑与Isbell拓扑一致．     

Domain函数空间上的Isbell拓扑和Scott拓扑的一致性

本文主要讨论了Domain函数空间上Isbell拓扑和Scott拓扑的一致性.利用Domain函数空间给出了一个例子: Scott拓扑有开滤子基的非连续的DCPO.     

关于Scott开滤子拓扑核紧性的注记

本文构造了两个例子:(1)利用康托三分集构造了一个非连续的DCPO,这个非连续DCPO关于所有Scott开滤子为子基生成的拓扑是核紧的,T0的,且以Scott开滤子为基,从而回答了[2]提出的一个问题;(2)利用Domain函数空间给出一个非连续的DCPO,其上的Scott拓扑有开滤子基,这个例子比[3]中给出的更直观.     

关于Lowen空间指数对象的一点注记

L-拓扑空间(X,△)称为一Lowen空间若△有一组由层特征函数构成的基,即△中形如a∧U,a∈L,U∈X的元素构成△的一组基.若L=[0,1],则(X,△)是一Lowen空间当且仅当(X,△)是一Lowen意义下的fzzy邻域空间.通过在函数空间上引入适当的L-拓扑结构,证明了若0∈L是一素元并且Lowen空间(X,△)的开集格是一连续格,则(X,△)是Lowen空间范畴中一指数对象.特别地,若一fuzzy邻域空间的开集格连续,则它是FNS中一指数对象.     

拟连续Domain的若干拓扑性质

对拟连续Domain D证明了:(1)双拓扑空间(D,σ(D),(D))为两两完全正则空间;(2)若D有可数基,则(max(D),σ(D)max(D))为正则空间当且仅当它为Polish空间;(3)拓扑空间(D,σb(D))为零维Tychonoff空间,其中σb(D)为D上Scott拓扑的b-拓扑。     

L-Fuzzy Domain上的广义Scott拓扑

本文研究了L-fuzzy domain上的广义Scott拓扑,利用[1]中引入的L-fuzzy domain.获得了其上的广义Scott拓扑,它是Domain上Scott拓扑的推广,证明了一个L-fuzzy单调映射是L-fuzzy Scott连续映射当且仅当它关于L-fuzzy domain上的广义Scott拓扑连续.     

［X→L］上的Isbell拓扑和Scott拓扑

本文证明了：对ｃｏｒｅｃｏｍｐａｃｔ空间Ｘ和具有最小元的有界完备连续ＤＣＰＯＬ，［Ｘ→Ｌ］上的Ｉｓｂｅｌｌ拓扑与Ｓｃｏｔｔ拓扑重合．并且构造两个反例说明：若Ｌ不具有最小元，或Ｌ具有最小元但不满足有界完备性，则［Ｘ→Ｌ］上的Ｉｓｂｅｌｌ拓扑与Ｓｃｏｔｔ拓扑不必重合．     

Z-拟连续domain上的Scott拓扑和Lawson拓扑

对一般子集系统Z,引入了Z-拟连续domain的概念,证明了Z-完备偏序集P是Z-拟连续的当且仅当P上的Z-Scott拓扑σZ(P)在集包含序下是超连续格;Z-拟连续domain P上的Z-Scott拓扑σZ(P)是Sober的当且仅当σZ(P)具有Rudin性质,P贼予Z-Lawson拓扑λZ(P)是pospace,且若P上的Z-Lawson开上集是Z-Scott开的,Z-Lawson开下集是下拓扑开的,则(P,λZ(P))为严格完全正则序空间.     

拓扑空间子集的最小开集和最大闭集

讨论对于拓扑空间子集A是否存在包含A的最小开集和是否存在包含于A的最大闭集问题,证明了拓扑空间X是一个T1空间之充分且必要条件是,对于X的每一个子集A,X中存在包含A的最小开集（存在包含于A的最大闭集）当且仅当A是X的开集（闭集）,同时给出几个例子说明了定理的条件.     

Z-拟连续domain上的Scott拓扑和Lawson拓扑

对一般子集系统Z,引入了Z-拟连续domain的概念,证明了Z-完备偏序集P是Z-拟连续的当且仅当P上的Z-Scott拓扑σ_z(P)在集包含序下是超连续格;Z-拟连续domain P上的Z-Scott拓扑σ_z(P)是Sober的当且仅当σ_z(P)具有Rudin性质,P赋予Z-Lawson拓扑λ_z(P)是pospace;且若P上的Z-Lawson开上集是Z-Scott开的,Z-Lawson开下集是下拓扑开的,则(P,λ_z(P))为严格完全正则序空间。     

On the compact-open and admissible topologies

It is known (see, for example, [H. Render, Nonstandard topology on function spaces with applications to hyperspaces, Trans. Amer. Math. Soc. 336 (1) (1993) 101-119; M. Escardo, J. Lawson, A. Simpson, Comparing cartesian closed categories of (core) compactly generated spaces, Topology Appl. 143 (2004) 105-145; D.N. Georgiou, S.D. Iliadis, F. Mynard, Function space topologies, in: Open Problems in Topology 2, Elsevier, 2007, pp. 15-23]) that the intersection of all admissible topologies on the set C(Y,Z) of all continuous maps of an arbitrary space Y into an arbitrary space Z, is always the greatest splitting topology (which in general is not admissible). The following, interesting in our opinion, problem is arised: when a given splitting topology (for example, the compact-open topology, the Isbell topology, and the greatest splitting topology) is the intersection of k admissible topologies, where k is a finite number. Of course, in this case this splitting topology will be the greatest splitting.In the case, where a given splitting topology is admissible the above number k is equal to one. For example, if Y is a locally compact Hausdorff space, then k=1 for the compact-open topology (see [R.H. Fox, On topologies for function spaces, Bull. Amer. Math. Soc. 51 (1945) 429-432; R. Arens, A topology for spaces of transformations, Ann. of Math. 47 (1946) 480-495; R. Arens, J. Dugundji, Topologies for function spaces, Pacific J. Math. 1 (1951) 5-31]). Also, if Y is a corecompact space, then k=1 for the Isbell topology (see [P. Lambrinos, B.K. Papadopoulos, The (strong) Isbell topology and (weakly) continuous lattices, in: Continuous Lattices and Applications, in: Lect. Notes Pure Appl. Math., vol. 101, Marcel Dekker, New York, 1984, pp. 191-211; F. Schwarz, S. Weck, Scott topology, Isbell topology, and continuous convergence, in: Lect. Notes Pure Appl. Math., vol. 101, Marcel Dekker, New York, 1984, pp. 251-271]).In [R. Arens, J. Dugundji, Topologies for function spaces, Pacific J. Math. 1 (1951) 5-31] a non-locally compact completely regular space Y is constructed such that the compact-open topology on C(Y,S), where S is the Sierpinski space, coincides with the greatest splitting topology (which is not admissible). This fact is proved by the construction of two admissible topologies on C(Y,S) whose intersection is the compact-open topology, that is k=2.In the present paper improving the method of [R. Arens, J. Dugundji, Topologies for function spaces, Pacific J. Math. 1 (1951) 5-31] we construct some other non-locally compact spaces Y such that the compact-open topology on C(Y,S) is the intersection of two admissible topologies. Also, we give some concrete problems concerning the above arised general problem.     

Coincidence of the Isbell and fine Isbell topologies

Let C(X,Y) be the set of all continuous functions from a topological space X into a topological space Y. We find conditions on X that make the Isbell and fine Isbell topologies on C(X,Y) equal for all Y. For zero-dimensional spaces X, we show there is a space Z such that the coincidence of the Isbell and fine Isbell topologies on C(X,Z) implies the coincidence on C(X,Y) for all Y. We then consider the question of when the Isbell and fine Isbell topologies coincide on the set of continuous real-valued functions. Our results are similar to results established for consonant spaces.     

Function spaces from core compact coherent spaces to continuous B-domains

It is proved in this paper that for a continuous B-domain L, the function space [X→L] is continuous for each core compact and coherent space X. Further, applications are given. It is proved that:

(1)

the function space from the unit interval to any bifinite domain which is not an L-domain is not Lawson compact;

(2)

the Isbell and Scott topologies on [X→L] agree for each continuous B-domain L and core compact coherent space X.

     

When is the Isbell topology a group topology?

Conditions on a topological space X under which the space C(X,R) of continuous real-valued maps with the Isbell topology κ is a topological group (topological vector space) are investigated. It is proved that the addition is jointly continuous at the zero function in Cκ(X,R) if and only if X is infraconsonant. This property is (formally) weaker than consonance, which implies that the Isbell and the compact-open topologies coincide. It is shown the translations are continuous in Cκ(X,R) if and only if the Isbell topology coincides with the fine Isbell topology. It is proved that these topologies coincide if X is prime (that is, with at most one non-isolated point), but do not even for some sums of two consonant prime spaces.     

Complete spaces and zero-one measures

It is the purpose of this paper to characterize the complete spaces in the sense of [6] by measure-theoretic properties. Let (X,) be a measurable space and let be a subpaving of satisfying certain closure properties, then X is-complete iff every 0,1-valued-regular measure on is a Dirac measure. In particular, we obtain Hewitt's well-known theorem that a completely regular space X is realcompact iff every 0,1-valued Baire measure on X is a Dirac measure. The main tool for our investigations is an extension theorem for measures due to Topsoe [10].     

Division and k-th root theorems for Q-manifolds

We prove that a locally compact ANR-space X is a Q-manifold if and only if it has the Disjoint Disk Property (DDP), all points of X are homological Z∞-points and X has the countable-dimensional approximation property (cd-AP), which means that each map f:K→X of a compact polyhedron can be approximated by a map with the countable-dimensional image. As an application we prove that a space X with DDP and cd-AP is a Q-manifold if some finite power of X is a Q-manifold. If some finite power of a space X with cd-AP is a Q-manifold, then X2 and X×[0,1] are Q-manifolds as well. We construct a countable familyχof spaces with DDP and cd-AP such that no space X∈χis homeomorphic to the Hilbert cube Q whereas the product X×Y of any different spaces X, Y∈χis homeomorphic to Q. We also show that no uncountable familyχwith such properties exists.     

Strongly continuous posets and the local Scott topology

In this paper, the concept of strongly continuous posets (SC-posets, for short) is introduced. A new intrinsic topology—the local Scott topology is defined and used to characterize SC-posets and weak monotone convergence spaces. Four notions of continuity on posets are compared in detail and some subtle counterexamples are constructed. Main results are: (1) A poset is an SC-poset iff its local Scott topology is equal to its Scott topology and is completely distributive iff it is a continuous precup; (2) For precups, PI-continuity, LC-continuity, SC-continuity and the usual continuity are equal, whereas they are mutually different for general posets; (3) A T₀-space is an SC-poset equipped with the Scott topology iff the space is a weak monotone convergence space with a completely distributive topology contained in the local Scott topology of the specialization order.     

环上的拓扑和偏序

在环R上引入了拓扑O[R]和偏序≤R,证明了(R,O[R])是可分的,第一可数的局部紧空间,并得出了如下结论:(1)(R*,O*[R])是T1的当且仅当O*[R]是离散的当且仅当R中的任一元r满足r=r2=-r;(2)若(R,O[R])是T0的,则U∈O[R]当且仅当U=↓U;(3)若R是伪有限的且对任意r都有〈r〉>2,则(R,≤R)是代数Domain;(4)若环R的特征数chR为2,则R是伪有限的当且仅当Rop是代数Domain。