5元素集合上T_0拓扑总数的计算

利用有限偏序集上的几个重要结果并借助于拓扑空间对应的特殊化序与拓扑之间的关系计算得出5元素集合上T0拓扑总数为4231,拓扑总数为6942.     

L-拟序集上的广义Alexandroff拓扑

在一类特殊的 L -拟序集上定义广义 Alexandroff拓扑 ,限制到通常的拟序集上就是 Alexandroff拓扑 ,并且该拓扑可以由其上的一族 Alexandroff拓扑取并得到。还证明任意一个拓扑空间的拓扑都可以表示为某个 L-拟序集上的广义 Alexandroff拓扑。     

τ-连续偏序集的网式刻画

利用cut算子,在偏序集上引入网的下极限收敛概念,讨论了它的一些性质,特别地,对任意包含于σ₂-拓扑的序相容拓扑τ,证明了一偏序集是τ-连续的当且仅当S-收敛是拓扑的当且仅当它是交τ-连续的且下极限收敛是拓扑的.     

L-拟序集上的广义Alexandroff拓扑与广义超度量空间上的广义Alexandroff拓扑

证明[10]中定义的L-拟序集上的广义Alexandroff拓扑是[2]中定义的广义超度量空间上的广义Alexandroff拓扑的推广，并且广义超度量空间中有关广义Alexandroff拓扑的许多性质都可以推广到L-拟序集中。     

近似空间的拓扑性质及其应用

近似空间(U,R)的全体可定义集构成X上的一个拓扑.本文在不要求论域U是有限的前提下探讨近似空间上这个拓扑的局部性质和可数性质,以及拓扑空间可近似化的充要条件及公理化体系,并寻找它们在粗糙集理论中的应用.     

偏序集的内蕴拓扑连通性北大核心

从序与拓扑的交叉考虑,进一步研究偏序集在多种内蕴拓扑下的连通性和局部连通性.主要结果有:(1)一个偏序集是序连通的当且仅当它赋予Alexandrov拓扑是连通的,也当且仅当它赋予Scott拓扑是连通的;(2)每一偏序集赋予Alexandrov拓扑是局部连通的,每一偏序集赋予Scott拓扑是局部连通的;(3)如果拓扑空间的特殊化偏序集序连通,则该拓扑空间是连通的;(4)构造反例说明了存在偏序集赋予下拓扑后是连通空间,但该偏序集本身不是序连通的.     

LF保序算子空间的ω-连通性

本文研究了LF保序算子空间的ω-连通性问题.利用LF保序算子空间的ω-远域和ω-连通集等概念,讨论了这些概念的特征性质.同时,给出了拓扑生成的F保序算子空间的若干ω-连通性质.     

Fuzzy拓扑共生结构与预序关系

A. Csáaszár在[1]中引入拓扑共生(Syntopogenous)结构的概念,将拓扑结构,邻近结构,一致结构适当地统一起来研究。近年来,A·K·Katsaras等人在[2,3,4]中分别提出Fuzzy序拓扑空间,Fuzzy拓扑共生空间的概念,给出了一些基本性质。在文[6]中,我们对以完全分配格L为值域的Fuzzy拓扑共生空间作了一些初步的讨论,得到包括它与L-fuzzy拓扑,邻近性,一致性的关系,连续性,连通性等的若干性质。本文将X上的L-fuzzy拓扑共生结构与X上的预序结构联系起来,讨论了L-fuzzy拓扑共生结构生成的预序,预序决定的L-fuzzy拓扑生成结构,以及递增(减)的L-fuzzy拓扑共生结构的性质;其它进一步的讨论将在随后的工作中给出。     

L—层次拓扑空间的有限覆盖性质

在L—层次拓扑空间中,引入了有限Ir—覆盖性质,并讨论了它的特性.证明了它是闭遗传的,它是在Ir—序同态下保持不变的等性质.     

Julia集的拓扑复杂性

研究有理函数及整函数Julia集的拓扑结构,刻画了有理函数Julia集的复杂性,展示了整函数在Fatou集上的动力学性质对其Julia集拓扑复杂性的影响.     

The Existence of the Complete and Completely Distributive Lattices

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Finite Intervals in the Lattice of Topologies

We prove a conjecture of Reinhold: that a finite lattice is isomorphic to an interval in the lattice of topologies on some set if and only if it is isomorphic to an interval in the lattice of topologies on a finite set.     

Topology vs generalized rough sets

This paper investigates the relationship between topology and generalized rough sets induced by binary relations. Some known results regarding the relation based rough sets are reviewed, and some new results are given. Particularly, the relationship between different topologies corresponding to the same rough set model is examined. These generalized rough sets are induced by inverse serial relations, reflexive relations and pre-order relations, respectively. We point that inverse serial relations are weakest relations which can induce topological spaces, and that different relation based generalized rough set models will induce different topological spaces. We proved that two known topologies corresponding to reflexive relation based rough set model given recently are different, and gave a condition under which the both are the same topology.     

Finite Intervals in the Lattice of Topologies

We discuss the question whether every finite interval in the lattice of all topologies on some set is isomorphic to an interval in the lattice of all topologies on a finite set – or, equivalently, whether the finite intervals in lattices of topologies are, up to isomorphism, exactly the duals of finite intervals in lattices of quasiorders. The answer to this question is in the affirmative at least for finite atomistic lattices. Applying recent results about intervals in lattices of quasiorders, we see that, for example, the five-element modular but non-distributive lattice cannot be an interval in the lattice of topologies. We show that a finite lattice whose greatest element is the join of two atoms is an interval of T ₀-topologies iff it is the four-element Boolean lattice or the five-element non-modular lattice. But only the first of these two selfdual lattices is an interval of orders because order intervals are known to be dually locally distributive.     

Compatible connectedness in graphs and topological spaces

A topology on the vertex set of a graphG iscompatible with the graph if every induced subgraph ofG is connected if and only if its vertex set is topologically connected. In the case of locally finite graphs with a finite number of components, it was shown in [11] that a compatible topology exists if and only if the graph is a comparability graph and that all such topologies are Alexandroff. The main results of Section 1 extend these results to a much wider class of graphs. In Section 2, we obtain sufficient conditions on a graph under which all the compatible topologies are Alexandroff and in the case of bipartite graphs we show that this condition is also necessary.     

A Characterization of Model Multi-colour Sets

Model sets are always Meyer sets, but not vice versa. This article is about characterizing model sets (general and regular) amongst the Meyer sets in terms of two associated dynamical systems. These two dynamical systems describe two very different topologies on point sets, one local and one global. In model sets these two are strongly interconnected and this connection is essentially definitive. The paper is set in the context of multi-colour sets, that is to say, point sets in which points come in a finite number of colours, that are loosely coupled together by finite local complexity. Communicated by Jean Bellissard submitted 8/10/04, accepted 15/02/05     

Classification of topologies on finite sets using graphs

With the use of directed graphs, we study topologies on finite sets. On this basis, we propose a new classification of these topologies. Some properties of T ₀-topologies on finite sets are proved. In particular, we prove the existence, in T ₀-topologies, of open sets containing any number of elements that does not exceed the cardinality of the set itself. Translated from Ukrains'kyi Matematychnyi Zhurnal, Vol. 60, No. 7, pp. 992–996, July, 2008.     

集合环

本文用集环来表现模糊集，得到了表现定理的新形式，并证明了这种表现可以有限化，即用有限个经典集近似刻划模糊集并且这样的刻划是同态的。最后，证明了集对方法是集环表现的特殊情形。     

An enumeration of distinct and non-isomorphic functional quasi-order relations

The problem of enumerating the number of distinct functional quasi-orders and the number of non-isomorphic functional quasi-orders that can be formed from a finite point set is considered. We establish the link between functional quasi-orders, functional digraphs, and functional Alexandroff topologies. As a result, we provide the generating functions associated to orbit-equivalent and orbit-isomorphic functional digraphs.