闭正则模糊拟阵的子拟阵的正则性

研究了闭正则模糊拟阵的子拟阵的正则性等性质.得到了闭正则模糊拟阵的两种子拟阵的正则性等性质,即k-子拟阵为闭正则模糊拟阵,限制子拟阵不是闭正则模糊拟阵,给出了闭正则模糊拟阵的收缩拟阵为闭正则模糊拟阵等结论.     

关于模糊截短列拟阵的研究

本文研究了导出拟阵序列为一个拟阵通过逐次截短得到的拟阵序列所确定的模糊拟阵。首先证明了这种模糊拟阵是闭正规模糊拟阵,接着讨论了它们的一些特殊性质,最后刻画了这类模糊拟阵。     

关于模糊拟阵的模糊秩研究

本文受正规模糊拟阵启发,定义了普通模糊拟阵的正规模糊基概念;然后利用基子集套方法,证明了闭模糊拟阵存在正规模糊基,在同一模糊拟阵中的正规模糊基的模糊势相等,正规模糊基的模糊势是同一模糊拟阵中的模糊基的最大模糊势等性质。通过这些性质,给出了用正规模糊基描述的闭正规模糊拟阵的充要条件。还利用这些性质,得到计算正规模糊基模糊势的公式;最后拓展普通拟阵的秩定义了一般模糊拟阵的模糊秩。通过模糊拟阵的闭包概念,证明了模糊拟阵的模糊秩等于正规模糊基的模糊势,并得到计算模糊拟阵模糊秩的公式。同时,详细讨论了模糊拟阵模糊秩的许多性质,还对利用模糊拟阵模糊秩研究模糊拟阵做了一点尝试。模糊秩是模糊拟阵的固有特征之一,通过模糊秩来研究模糊拟阵,或者从模糊拟阵来讨论模糊秩都有大量工作可以做。     

关于G-V模糊拟阵的对偶模糊拟阵概念的推广

模糊拟阵的研究方法之一就是通过基本序列和导出拟阵序列将模糊拟阵问题转化为普通拟阵问题来进行研究。本文正是采用这个研究方法,主要完成了三项工作:一是给出并证明了闭正规模糊拟阵和正规模糊拟阵的几个充要条件;二是将对偶模糊拟阵概念从闭正规模糊拟阵推广到正规模糊拟阵并讨论了有关性质和计算;三是证明了除正规模糊拟阵外,其他模糊拟阵不存在这样的对偶模糊拟阵。     

初等模糊拟阵与基本截片模糊拟阵的若干性质

对两种初等模糊拟阵和基本截片模糊拟阵的定义进行了比较,研究了它们之间的关系.研究了初等模糊拟阵的若干性质,得到了初等模糊拟阵和基本截片模糊拟阵为闭正则模糊拟阵等结论,给出了初等模糊拟阵的等价刻画以及初等模糊拟阵与其截拟阵之间的关系.     

闭模糊拟阵模糊基的判定

通过讨论闭模糊拟阵的导出拟阵序列和模糊基的结构,找到了判定闭模糊拟阵的模糊基的一个充要条件。根据此充要条件,给出了从导出拟阵序列得到闭模糊拟阵的模糊基的一种算法。     

关于模糊拟阵的圈子集套

本文主要采用通过导出拟阵来研究模糊拟阵的方法,探讨模糊拟阵模糊圈的性质和构造。这种方法的基本原理是两条:闭模糊拟阵可以由其导出拟阵序列和基本序列唯一确定,而模糊圈可以被分解为导出拟阵的圈和独立子集套。借助这种方法,本文主要做了三方面工作:一是讨论了模糊拟阵的模糊圈集和导出拟阵圈集之间的关系。比如模糊圈、初等模糊圈和最大初等模糊圈与导出拟阵圈之间的关系等;二是基于模糊圈和导出拟阵圈之间的关系,定义了导出拟阵圈函数和导出拟阵圈子集套两个概念。然后,详细研究了利用这两个概念来构造模糊圈的方法。同时,分析了在圈子集套和数列满足什么条件时,这种方法有效;三是分别用导出拟阵圈和圈子集套给出了准模糊图拟阵和精细模糊拟阵的充要条件。     

强[0,1]-拟阵

本文研究一类特殊的[0,1]-拟阵,即强[0,1]-拟阵,它属于G-V模糊拟阵类和H模糊拟阵类之交,证明了强[0,1]-拟阵的模糊基交换性定理。     

关于一致模糊横贯拟阵的研究

"模糊横贯拟阵'的反例"~([1])一文指出不是所有模糊集族的模糊部分横贯都能构成一个模糊拟阵的模糊独立集族。本文找到一类满足"一致性"条件的模糊集族,其模糊部分横贯全体一定能组成一个模糊拟阵的模糊独立集族(称这类模糊拟阵为一致模糊横贯拟阵);然后详细讨论了一致模糊横贯拟阵的基本序列、导出拟阵序列和模糊基等许多性质;还讨论了一致模糊横贯拟阵与准模糊图拟阵的关系,与正规模糊拟阵的关系;最后证明了一致模糊横贯拟阵是一类准模糊图拟阵。     

广义拟阵的约简与近似算子

广义拟阵作为拟阵结构的拓广形式之一,在许多领域扮演着重要的角色.为了将广义拟阵理论进一步地拓广,首先基于覆盖粗糙集,提出可约广义拟阵的定义,并给出相关的算法和实例.其次,为了实现不同广义拟阵知识层面上知识的表述,将拟阵中秩强映射的定义推广到广义拟阵中,并且基于此定义,对于广义拟阵提出一种特殊的秩强映射——保基秩强映射....     

双圈拟阵

Sim■es Pereira于1992年提出双圈拟阵.本文讨论了(i)双圈拟阵及其秩函数;(ii)次模函数在双圈拟阵中的应用;(iii)双圈拟阵B(G)的横贯拟阵.主要结果:1°由圈矩阵Bf=[I,Bf12]和圈秩的概念,推出M(f0)为双圈拟阵;2°证明了双圈拟阵B(G)等于由子集族{Av∶v∈V(G)},e与v在G中相关联}所确定的横贯拟阵;3°用不同于Matthews(1977)的方法证明了(iii).     

An Adjacency Criterion for Coxeter Matroids

A Coxeter matroid is a generalization of matroid, ordinary matroid being the case corresponding to the family of Coxeter groups A _n , which are isomorphic to the symmetric groups. A basic result in the subject is a geometric characterization of Coxeter matroid in terms of the matroid polytope, a result first stated by Gelfand and Serganova. This paper concerns properties of the matroid polytope. In particular, a criterion is given for adjacency of vertices in the matroid polytope.     

Two algorithms for matroids

A matroid may be characterized by the collection of its bases or by the collection of its circuits. Along with any matroid is a uniquely determined dual matroid. Given the bases of a matroid, it is possible to show that base complements are precisely the bases of the dual. So it is easy to construct bases of the dual given the bases of the original matroid.This paper provides two results. The first enables construction of all circuits of the dual matroid from circuits of the original matroid. The second constructs all bases of a matroid from its circuits.     

拟阵的可去圈

本首先用拟阵语言将图论的新概念定义成了拟阵的新概念，然后用拟阵语言将Goddyn和Heuevl所得的图论上的新结果平移成了拟阵的新结果，最后用拟阵的方法对它们给出了新的证明。     

On the (co)girth of a connected matroid

This article studies the girth and cogirth problems for a connected matroid. The problem of finding the cogirth of a graphic matroid has been intensively studied, but studies on the equivalent problem for a vector matroid or a general matroid have been rarely reported. Based on the duality and connectivity of a matroid, we prove properties associated with the girth and cogirth of a matroid whose contraction or restriction is disconnected. Then, we devise algorithms that find the cogirth of a matroid M from the matroids associated with the direct sum components of the restriction of M. As a result, the problem of finding the (co)girth of a matroid can be decomposed into a set of smaller sub-problems, which helps alleviate the computation. Finally, we implement and demonstrate the application of our algorithms to vector matroids.     

Facial structures of lattice path matroid polytopes

A lattice path matroid is a transversal matroid corresponding to a pair of lattice paths on the plane. A matroid base polytope is the polytope whose vertices are the incidence vectors of the bases of the given matroid. In this paper, we study the facial structures of matroid base polytopes corresponding to lattice path matroids. In the case of a border strip, we show that all faces of a lattice path matroid polytope can be described by certain subsets of deletions, contractions, and direct sums. In particular, we express them in terms of the lattice path obtained from the border strip. Subsequently, the facial structures of a lattice path matroid polytope for a general case are explained in terms of certain tilings of skew shapes inside the given region.     

Flag enumerations of matroid base polytopes

In this paper, we study flag structures of matroid base polytopes. We describe faces of matroid base polytopes in terms of matroid data, and give conditions for hyperplane splits of matroid base polytopes. Also, we show how the cd-index of a polytope can be expressed when a polytope is split by a hyperplane, and apply these to the cd-index of a matroid base polytope of a rank 2 matroid.     

准模糊图拟阵基图的最大权基与字典序最大的基

模糊拟阵的基图是模糊拟阵的基本概念.在准模糊图拟阵的基础上,给出了准模糊图拟阵基图的最大权基与字典序最大的基的性质,这将有利于模糊拟阵从基础研究逐渐转向应用研究.     

Truncation Formulas for Invariant Polynomials of Matroids and Geometric Lattices

This paper considers the truncation of matroids and geometric lattices. It is shown that the truncated matroid of a representable matroid is again representable. Truncation formulas are given for the coboundary and M?bius polynomial of a geometric lattice and the spectrum polynomial of a matroid, generalizing the truncation formula of the rank generating polynomial of a matroid by Britz.     

Mod 2 cohomology of combinatorial Grassmannians

Matroid bundles, introduced by MacPherson, are combinatorial analogues of real vector bundles. This paper sets up the foundations of matroid bundles. It defines a natural transformation from isomorphism classes of real vector bundles to isomorphism classes of matroid bundles. It then gives a transformation from matroid bundles to spherical quasifibrations, by showing that the geometric realization of a matroid bundle is a spherical quasifibration. The poset of oriented matroids of a fixed rank classifies matroid bundles, and the above transformations give a splitting from topology to combinatorics back to topology. A consequence is that the mod 2 cohomology of the poset of rank k oriented matroids (this poset classifies matroid bundles) contains the free polynomial ring on the first k Stiefel-Whitney classes.