6元素集合上T0拓扑总数的计算

文中证明了有限预序集与有限偏序集的一些性质,并基于有限集上的拓扑和其上预序的一一对应关系,利用这些性质通过对极小元和极大元个数进行分类讨论,以一种有别于计算机算法而又容易理解的计算方法得出6元素集合上的T₀拓扑总数为130023.     

完全分配格上拓扑生成序的加细及其性质

在文[1]中,作者建立了完全分配格上的共生结构的一般理论,研究了余拓扑,拟一致和T结构的一致化结构。本文引进了完全分配格L上半拓扑生成序加细的概念,研究了其性质,得到了一系列重要的结论,为进一步研究完全分配格上拓扑共生结构的加细奠定了基础。     

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。     

正则F集空间中的度量拓扑

本文证明了Ｒ＾ｎ上正则Ｆ集收敛拓扑空间是完备的、可分的度量空间，给出了该种度量的具体表达形式。本文还讨论了弱收敛度量拓扑与正则Ｆ集上另外两种度量拓扑－一致收敛拓扑及积分收敛拓扑－之间的关系。     

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。     

偏序集上的测度拓扑和全测度

在偏序集上引入测度拓扑和全测度概念,研究其性质以及与其它内蕴拓扑间的众多关系。主要结果有:连续偏序集的测度拓扑实际上是由其上的任一全测度所决定且可由它的定向完备化上的测度拓扑和全测度分别限制得到;当连续偏序集还是D om a in时,其上的测度拓扑与μ拓扑一致;连续偏序集有可数基当且仅当其上的测度拓扑是可分的;一个网如果测度收敛则存在最终上确界;任一ω连续偏序集上都存在全测度。     

关于函数空间Y~X上三个特殊拓扑间关系的讨论

本文对函数空间上的一致收敛拓扑、紧收敛拓扑及 Cauchy收敛拓扑之间的关系进行了讨论 ,给出了这三个拓扑间两两等价的充要条件     

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.     

有限偏序集与4元素集合上T_0拓扑总数的计算

证明了有限偏序集的几个重要结果,利用这些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4元素集合上T0拓扑总数为219,拓扑总数为355.     

测度拓扑和连续偏序集的刻画

研究偏序集上的测度拓扑以及与其它内蕴拓扑间的关系,利用测度拓扑刻画了偏序集的连续性.构造了反例说明存在完全分配格,其上的测度拓扑不是连续格从而不是局部紧拓扑.     

On Series of Ordinals and Combinatorics

This paper deals mainly with generalizations of results in finitary combinatorics to infinite ordinals. It is well-known that for finite ordinals ∑_bT<αβ is the number of 2-element subsets of an α-element set. It is shown here that for any well-ordered set of arbitrary infinite order type α, ∑_bT<αβ is the ordinal of the set M of 2-element subsets, where M is ordered in some natural way. The result is then extended to evaluating the ordinal of the set of all n-element subsets for each natural number n ≥ 2. Moreover, series ∑_β<αf(β) are investigated and evaluated, where α is a limit ordinal and the function f belongs to a certain class of functions containing polynomials with natural number coefficients. The tools developed for this result can be extended to cover all infinite α, but the case of finite α appears to be quite problematic.     

On the structure of IO n

We study the structure of the semigroup IO _n of all order-preserving partial bijections on an n-element set. For this semigroup we describe maximal subsemigroups, maximal inverse subsemigroups, automorphisms and maximal nilpotent subsemigroups. We also calculate the maximal cardinality for the nilpotent subsemigroups in IO _n which happens to be given by the n-th Catalan number.     

Number of labeled topologies on ten points

The number of all the topologies that can be introduced on a fixed set of ten points is found. It is equal to 8,977,053,873,043. Out of these, 6,611,065,248,783 topologies satisfy the separation axiom T_o.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 86, pp. 5–10, 1979.     

On the Structure of IO n

Abstract. We study the structure of the semigroup IO _n of all order-preserving partial bijections on an n -element set. For this semigroup we describe maximal subsemigroups, maximal inverse subsemigroups, automorphisms and maximal nilpotent subsemigroups. We also calculate the maximal cardinality for the nilpotent subsemigroups in IO _n which happens to be given by the n -th Catalan number.     

Bargraph statistics on words and set partitions

In this paper, we consider statistics on partitions of an n-element set represented as a subset of the bargraphs that have n horizontal steps. More precisely, we find the joint distribution of the area and up step statistics on the latter subset of bargraphs, thereby obtaining new refined counts on partitions having a fixed number of blocks. Furthermore, we give explicit formulas in terms of the Stirling numbers for the total area and number of up steps in bargraphs corresponding to partitions, providing both algebraic and combinatorial proofs. Finally, we find asymptotic estimates for the average and total values of these statistics and as a consequence obtain some new identities for the Stirling and Bell numbers.     

The semigroups of order 9 and their automorphism groups

We report the number of semigroups with 9 elements up to isomorphism or anti-isomorphism to be 52?989?400?714?478 and up to isomorphism to be 105?978?177?936?292. We obtained these results by combining computer search with recently published formulae for the number of nilpotent semigroups of degree 3. We further provide a complete account of the automorphism groups of the semigroups with at most 9 elements. We use this information to deduce that there are 148?195?347?518?186 distinct associative binary operations on an 8-element set and 38?447?365?355?811?944?462 on a 9-element set.     

Asymptotic bounds for irredundant and mixed Ramsey numbers

The irredundant Ramsey number s(m, n) is the smallest N such that in every red-blue coloring of the edges of K_N, either the blue graph contains an m-element irredundant set or the red graph contains an n-element irredundant set. The definition of the mixed Ramsey number t(m, n) differs from s(m, n) in that the n-element irredundant set is replaced by an n-element independent set. We prove asymptotic lower bounds for s(n, n) and t(m, n) (with m fixed and n large) and a general upper bound for t(3, n). © 1993 John Wiley & Sons, Inc.     

The number of labeled topologies on nine points

The number of all topologies which can be introduced on a fixed set of nine points is found. It is equal to 63 260 289 423. Of them 44 511 042 511 are topologies with the axiom of separability T₀.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 75, pp. 35–42, 1978.     

The clone of operations preserving a cycle with loops

We consider all the binary relations on a k-element set which, when viewed as directed graphs, consist of a k-cycle and some loops. If k ≥ 3 and the relation has at least two loops, we show that it is only preserved by essentially unary operations. In all other cases, the relation is preserved by operations that depend on a greater number of variables. Received March 9, 2006; accepted in final form September 14, 2007.