单调概念格性质研究

概念格是知识表示和数据分析的重要工具,单调概念格是概念格的推广。本文就Deogun等提出的单调概念格进行了两方面的研究:一,指出Deogun等提出的单调概念格性质的错误并加以修正;二,证明单调概念格就是闭格,从而找到用拓扑闭包算子和拓扑交结构来表示单调概念格的两种格表示方法,并建立起单调概念格与有上界的拓扑交结构的范畴等价。本文所建立的单调概念格的拓扑表示方法将方便我们进一步研究单调概念格的构造算法、约简算法和实际应用,具有理论和实际的双重意义。     

基于格值逻辑的模糊概念格

从逻辑的角度,将非经典逻辑之一的格值逻辑引入概念格,建立了格值模糊形式背景,通过格结构来刻画对象与属性之间的模糊关系,证明了由蕴涵算子诱导的算子对是伽罗瓦连接,并讨论了相关的一些性质,进而给出了格值模糊概念格的构造算法.格值模糊概念格的建立为模糊性与不可比较性信息的处理提供了可靠的数学工具.     

一种新的概念格增量维护算法

形式概念分析在数据分析以及机器学习领域得到了广泛的应用,作为核心数据结构的概念格的构造算法一直是形式概念分析领域的研究热点.根据概念外延的补集性质,给出并证明了概念的生成定理和超概念的生成定理,并以此为基础提出了一种新的概念格的增量维护算法,包括概念的生成和序关系建立算法,并给出了一个应用示例.     

基于粗糙集方法的概念格理论研究综述

概念格与粗糙集理论是软计算领域的两种不同方法,它们都在数据挖掘、知识工程、信息检索、人工智能、系统分析与管理决策等领域有重要应用。在介绍概念格基本概念的基础上,对近年来借助粗糙集方法研究概念格的粗糙集近似扩充、概念格的约简理论与方法、变精度概念格及基于概念格的模糊推理、概念粒计算系统的数学模型及迭代算法等方面进行了综述,并提出了进一步研究的问题和方向。     

概念粒计算系统外延的判别定理

概念粒计算系统是基于两个完备格之间的外延内涵算子和内涵外延算子构成的模型系统,它包括经典概念格,L模糊概念格及变精度概念格等.本文以三种概念粒计算系统为模型研究了概念外延的特征及其相互关系,给出了外延为经典集、内涵为模糊集和外延为模糊集、内涵为经典集这两种概念粒计算系统的概念外延判别定理,并且讨论了几种模型概念之间的关系与性质.     

模糊概念格

概念格是研究和处理概念内涵与外延确定性关系的数学方法 ,已成为一种有效的数据分析方法。本文进一步探讨概念内涵与外延的不确定关系的模糊映射 ,给出相应的隶属函数的一些基本数学性质 ,证明全体模糊概念构成一个完全格。     

关于模糊横贯拟阵的最大表示

本文利用横贯拟阵的最大表示及其性质来定义和研究模糊横贯拟阵的最大表示问题。首先,推广横贯拟阵的最大表示概念定义横贯拟阵的p-最大表示。同时解决了p-最大表示的存在性、唯一性和算法等问题;然后,再推广横贯拟阵的最大概念定义模糊横贯拟阵的最大表示。证明了模糊横贯拟阵的最大表示也是简洁表示,最大表示的截短子集族是导出横贯拟阵的p-最大表示以及其它性质和结论;接下来,利用这些研究结果,通过简洁表示和p-最大表示概念提出并证明了模糊横贯拟阵的表示是最大表示的充要条件;最后,根据这个充要条件证明了模糊横贯拟阵的最大表示总是存在并且唯一。给出了从模糊横贯拟阵的一个表示计算最大表示的算法,而且证明了这个算法的有效性。     

基于粗集与概念格的属性简约讨论

概念格的属性简约是在形式背景下解决复杂问题的重要途径,通过对概念格、粗糙集的讨论,将两者有效结合,并借助粗糙集上(下)近似的方法,得出了一个对概念格属性简约的方法,方法将二维的概念格属性简约转化为一维的一种对象格的简约,避免了形式背景下的概念的计算和进一步的可辨识矩阵的计算,方法简便,算法简单易实现,是概念格属性简约有效的算法.     

超拟阵的独立集公理、基公理和圈公理

Dunstan等在1972年首先提出了超拟阵的概念,用以将定义拟阵的承载集合从有限集推广到偏序集.Barnabei等在1998年研究了另一种偏序集上的拟阵结构,即偏序集拟阵.由有限分配格和有限偏序集之间的对应关系可知,偏序集拟阵就是分配格上的超拟阵.本文研究超拟阵的公理系统,建立模格上的超拟阵的独立元公理,证明模格上超拟阵的中间基性质和基的交换性质并用这两个性质分别刻画了模超拟阵.最后指出了Barnabei等给出的分配超拟阵圈公理中的一个错误,重新提出并证明分配超拟阵的圈消去性质并建立了分配超拟阵的圈公理.作为圈消去性质的一个应用,本文证明了分配超拟阵中覆盖基的元素包含唯一的圈.     

利用矩阵行秩生成概念格的一种算法

概念格是根据二元关系提出的一种概念层次结构,它描述了对象和属性的关系,利用矩阵行秩的层次思想提出了一种基于矩阵行秩的概念格生成算法,并用实例描述了对象和属性之间的概念关系.     

Whitney numbers of matroid extensions and co-extensions

Crapo found that single-element extensions of matroid are equivalent to modular cuts. This paper will study the single-element extension and co-extension of a matroid and establish the upper semi-continuity for the signless coefficients of Whitney polynomials and Whitney numbers on both extensions via its extension lattice, a lattice of all non-empty modular cuts.     

Consistent lattices and Steinitz spaces

It is well-known that a finite lattice L is isomorphic to the lattice of flats of a matroid if and only if L is geometric. A result due to Edelman (see [1], Theorem 3.3) states that a lattice is meet-distributive if and only if it is isomorphic to the lattice of all closed sets of a convex geometry. In this note we prove that a finite lattice is the lattice of closed sets of a closure space with the Steinitz exchange property if and only if it is a consistent lattice. Received February 28, 1997; accepted in final form February 2, 1998.     

模糊幂格

本文研究了格向其模糊幂集上提升的问题.利用模糊集理论,引入了模糊幂格的概念,获得了模糊幂格及其模糊理想的若干基本性质,推广了格的结果.     

A partition-based approach towards constructing Galois (concept) lattices

Galois lattices and formal concept analysis of binary relations have proved useful in the resolution of many problems of theoretical or practical interest. Recent studies of practical applications in data mining and software engineering have put the emphasis on the need for both efficient and flexible algorithms to construct the lattice. Our paper presents a novel approach for lattice construction based on the apposition of binary relation fragments. We extend the existing theory to a complete characterization of the global Galois (concept) lattice as a substructure of the direct product of the lattices related to fragments. The structural properties underlie a procedure for extracting the global lattice from the direct product, which is the basis for a full-scale lattice construction algorithm implementing a divide-and-conquer strategy. The paper provides a complexity analysis of the algorithm together with some results about its practical performance and describes a class of binary relations for which the algorithm outperforms the most efficient lattice-constructing methods.     

Concerning the shape of a geometric lattice

A well-known conjecture states that the Whitney numbers of the second kind of a geometric lattice (simple matroid) are logarithmically concave. We show this conjecture to be equivalent to proving an upper bound on the number of new copoints in the free erection of the associated simple matroid M. A bound on the number of these new copoints is given in terms of the copoints and colines of M. Also, the points-lines-planes conjecture is shown to be equivalent to a problem concerning the number of subgraphs of a certain bipartite graph whose vertices are the points and lines of a geometric lattice.     

关于强映射下几何格的一个公开问题

In this paper, some properties of the image of the geometric lattice of a graphic matroid under a strong map are discussed, and a negative answer to the related open question of Welsh‘s book is given.     

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.