Exponential Objects in Coreflective or Quotient Reflective Subconstructs: A Comparison

We prove that in the construct PRAP of pre-approach spaces the class of exponential objects completely determines the exponential objects in certain subconstructs. We show that Exp B Exp PRAP for every coreflective subconstruct B and from this inclusion we deduce the equality Exp B = B Exp PRAP for every subconstruct B that is coreflective and finitely productive. We prove that the same equality holds for non-trivial quotient reflective subconstructs. These results induce well known answers to similar questions on the construct of pretopological spaces and are compared to the topological situation.     

Simultaneously reflective and coreflective full subconstructs of stratified L-topological spaces are concretely reflective and coreflective

Let L be a completely distributive lattice. A stratified L-topology on a set X is a subfamily of L-subsets of X which is closed with respect to arbitrary suprema and finite infinima, and contains all the constants. In this paper, it is shown that every simultaneously reflective and coreflective full subconstruct of stratified L-topological spaces is necessarily concretely reflective and coreflective. In other words, every such subconstruct is necessarily both initially and finally closed. As an application, it is demonstrated that the construct of bitopological spaces has exactly 4 simultaneously reflective and coreflective full subconstructs.     

FUZZY PRETOPOLOGICAL SPACES, AN EXTENSIONAL TOPOLOGICAL EXTENSION OF FTS

O.Introduction'ByacrazytopologyonasetXwemeanasubsetofixwhichisclosedunderfiniteintersections,arbitraryulilonsandcolltainsalltheconstantfuZzysets.ItiswellknownthatthecategoryFTSoffuzzytopologicalspacesisawell--fibredtopologicalconstruct,andsinceitcoDtainsthecategoryTopasabothreflectiveandcoreflectivesubcategory)likeTOP,thiscategorylacksmanyconvenientpropertiessuchasextensionality(fordefinitionsee[6]or4.1inthispaper),cartesianclosednessandbeingatopologicaluniverse(see[1,6]fordefinitons).SoH…     

Lower and upper fuzzy topological subhypergroups

This paper provides a new connection between algebraic hyperstructures and fuzzy sets. More specifically, using both properties of fuzzy topological spaces and those of fuzzy subhypergroups, we define the notions of lower (upper) fuzzy topological subhypergroups of a hypergroup endowed with a fuzzy topology. Some results concerning the image and the inverse image of a lower (upper) topological subhypergroup under a very good homomorphism of hypergroups (endowed with fuzzy topologies) are pointed out.     

Exponential objects and Cartesian closedness in the constructPrtop

We give an internal characterization of the exponential objects in the constructPrtop and investigate Cartesian closedness for coreflective or topological full subconstructs ofPrtop. If $ is the set {0} {1/n;n 1} endowed with the topology induced by the real line, we show that there is no full coreflective subconstruct ofPrtop containing $ and which is Cartesian closed. With regard to topological full subconstructs ofPrtop we give an example of a Cartesian closed one that is large enough to contain all topological Fréchet spaces and allT ₁ pretopological Fréchet spaces.Aspirant NFWO     

L—不分明拓扑空间的Alexandorff紧化

给出了一般的Ｌ－不分明拓扑空间的Ａｌｅｘａｎｄｏｒｆｆ紧化，并且对弱诱导空间证明了该紧化是弱诱导紧化类中唯一最小的紧化。     

Almost compactness in fuzzy topological spaces

We introduce and study almost compactness for fuzzy topological spaces. We show that the almost continuous image of an almost compact fuzzy topological space is almost compact. Moreover, we show that generally almost compactness for fuzzy topological spaces is not product-invariant, but if X and Y are almost fuzzy topological spaces and X is product related to Y, then their fuzzy topological product is almost compact.     

Categorical Properties of Probabilistic Convergence Spaces

The purpose of this paper is to discuss some categorical properties of probabilistic convergence spaces. Its main theses are: (1) the construct P-PrTop of probabilistic pretopological spaces is the extensional topological hull of the construct FTPcs of FT-diagonal probabilistic convergence spaces for every triangular norm T; (2) the construct P-PsTop of probabilistic pseudotopological spaces is the topological universe hull of FTPcs for every triangular norm T.     

Stable Subconstructs: A Correction and New Results

In Lowen and Wuyts (Appl Categ Struct 8:235–245, 2000) the authors studied the simultaneously concretely reflective and concretely coreflective subconstructs of the category Ap of approach spaces. For the sake of shortness we call such subconstructs stable. Using a technique introduced in Herrlich and Lowen (1999) it was possible to explicitly describe such stable subconstructs by a condition on the objects which used certain subsets of [0, ∞ ]. Thus each stable subconstruct Ap _m described in [9] corresponds to the subset {0} ∪ [m, ∞ ] ⊂ [0, ∞ ] for m ∈ [0, ∞ ]. Although this characterization is correct, Theorem 4.7 in [9] stating that the subconstructs Ap _m were the only stable subconstructs of Ap is not. The main results, which together prove that the only stable subconstructs are those where a restriction is put on the range of the distances of the objects, are upheld, but it turns out that not only the sets {0} ∪ [m, ∞ ], but actually each closed subsemigroup of [0, ∞ ] determines a stable subconstruct (albeit again in exactly the same way as characterized in [9]). In the first part of our paper, Sections 1 and 2, we develop the general technique, which is totally different to the one from [3], and in Theorem 2.13 we prove the main result for the case of approach spaces. The technique which we develop is also applicable to other cases. Thus, in Section 3, more precisely in Theorems 3.9 and 3.11, we give the complete solution to the corresponding characterization problem for the constructs pq Met ^∞ of pseudo-quasi-metric spaces and p Met ^∞ of pseudometric spaces and in Section 4 we briefly sketch how the technique can be adapted and used to also completely solve the problem in the case of more general types of approach spaces and metric spaces. At the same time, in all cases, we are able to give necessary and sufficient conditions under which two stable subconstructs of one of these topological constructs are concretely isomorphic. It turns out that in all cases there are 2^à₀2^{\aleph_0} non-concretely isomorphic stable subconstructs.     

Bornologies and metrically generated theories

Bornologies axiomatize an abstract notion of bounded sets and are introduced as collections of subsets satisfying a number of consistency properties. Bornological spaces form a topological construct, the morphisms of which are those functions which preserve bounded sets. A typical example is a bornology generated by a metric, i.e. the collection of all bounded sets for that metric. In a recent paper [E. Colebunders, R. Lowen, Metrically generated theories, Proc. Amer. Math. Soc. 133 (2005) 1547-1556] the authors noted that many examples are known of natural functors describing the transition from categories of metric spaces to the “metrizable” objects in some given topological construct such that, in some natural way, the metrizable objects generate the whole construct. These constructs can be axiomatically described and are called metrically generated. The construct of bornological spaces is not metrically generated, but an important large subconstruct is. We also encounter other important examples of metrically generated constructs, the constructs of Lipschitz spaces, of uniform spaces and of completely regular spaces. In this paper, the unified setting of metrically generated theories is used to study the functorial relationship between these constructs and the one of bornological spaces.     

关于模糊拓扑环的直积

给出模糊拓扑环族直积的定义,研究它的性质,及任意模糊拓扑环族直积、与其模糊拓扑子环,与其模糊拓扑剩余环之间的同构问题.并对(QU)型模糊拓扑环关于上述问题进行研究.     

函数空间上的模糊线性拓扑

本文给出了模糊拓扑向量空间（Ｘ，Ｗ）到（Ｙ，Ｊ）的函数族Ｆ上的模糊线性拓扑，证明了若值域空间（Ｙ，Ｊ）是（Ｑ）型的、局部凸的模糊拓扑向量空间，则（Ｆ，），也是型的、局部凸的模糊拓扑向量空间。     

LF拓扑线性空间上Fuzzy线性泛函的连续性

文（４）中给出了Ｘ（Ｌ）上的模糊线性算子的定义。作为其特例，本文证明了ＬＦ拓扑线性空间上模糊线性泛函连续性的几个等价命题和模糊线性泛函的Ｈａｈｎ－Ｂａｎａｃｈ延拓定理，进而给出了ＬＦ拓扑线性空间上存在非零连续模糊线性泛函的一个充要条件。     

关于模糊拓扑环的模糊度量化

本文引入了模糊拓扑环可广义模糊度量化 ,可模糊伪度量化及可模糊度量化三个概念 ;并分别得到了模糊拓扑环可广义模糊度量化 ,可模糊伪度量化及可模糊度量化的三个充分必要条件     

Fuzzy topological vector spaces I

Some of the properties of fuzzy topological vector spaces are investigated. Also, there are given necessary and sufficient conditions for a family of fuzzy sets, in a vector space E, to be the family of all neighborhoods of zero for a fuzzy linear topology.     

Almost Fuzzy Compactness in L-fuzzy Top ological Spaces

In this paper, the notion of almost fuzzy compactness is defined in L-fuzzy topological spaces by means of inequality, where L is a completely distributive DeMorgan algebra. Its properties are discusse...     

关于(QU)型模糊拓扑群的直积

研究(QU)型模糊拓扑群族直积,证明了任意(QU)型模糊拓扑群族的直积仍是(QU)型模糊拓扑群;研究了(QU)型模糊拓扑群族直积的模糊单位元之重域基的结构,得到了(QU)型模糊拓扑群族直积的一些重要性质.     

关于Fuzzy拓扑线性空间的某些结果

本文给出了Ｆｕｚｚｙ拓扑线性空间的若干特征刻划，简化了判断Ｆｕｚｚｙ拓扑线性空间的条件，研究了Ｆｕｚｚｙ拓扑线性空间的层次结构，揭示了Ｆｕｚｚｙ拓扑线性空间与分明拓扑线性空间的内在联系，得到了Ｆｕｚｚｙ拓扑线性空间的“平移不变性”与“局部凸性”都是可截性质。     

关于生成I(L)-fuzzy拓扑空间问题的研究

以生成I(L)拓扑空间为基础,首先引入了Ω_L,I_L等算子及I(L)-fuzzy拓扑空间的概念,其次研究了该拓扑空间的基本性质及算子的相应运算规则,最后讨论了此拓扑空间与I(L)-fuzzy拓扑空间的关系.得到了生成I(L)-fuzzy拓扑空军的相应性质.     

Fuzzy拓扑体

引入了 Fuzzy拓扑体的定义 ,研究了它的性质 ,得到了借助于θλ的重域系及开重域基刻画 Fuzz拓扑体的充要条件 ;为 Fuzzy拓扑体理论研究提供了框架和工具 .