概念格的粗糙近似比较研究

形式背景产生了概念格,每个节点由外延和内涵组成.对形式背景论域中的任何一个子集,可用外延来近似,在这方面已有了4种方法.对这些方法进行了比较研究,利用粗糙集理论证明了用这些方法所求出的概念的上近似外延是相同的,并利用粗糙集理论研究了概念格属性约简后,原来方法对结果的一致性.     

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。     

基于Vague粗糙集信息熵的属性约简算法

针对复杂系统分析中的数据信息冗余问题,提出一种基于Vague粗糙集信息熵的属性约简算法。首先,对Vague粗糙集相关概念进行拓展,提出Vague粗糙集的扩展信息熵和广义信息熵的模型;其次,对基于信息熵的属性重要性度量和属性约简原理进行研究,进而提出了一种基于Vague粗糙集信息熵的监督式属性约简算法;最后,选取UCI数据库对算法性能进行验证,计算结果表明该算法实用有效。     

基于截形式背景的属性约简分析

在模糊概念格中讨论了基于截形式背景的属性约简,其中着重分析了在精度的偏序关系下属性约简的包含关系,并证明了此说法的正确性,进而还举例说明了其正确性;在此基础之上,本文还给出了在用不同精度把模糊概念格转换了经典概念格时造成的误差,并给出其算法,最后举例说明其有效性.     

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.     

基于矩阵的可变粒度变精度邻域粗糙集近似集更新方法

邻域粗糙集可以同时处理名义与数值属性,多粒度粗糙集提供多个粒度视角下的目标概念近似,变精度粗糙集使得近似集计算不再局限于完全包含。本文首先提出了一种同时具有以上三种粗糙集模型长处并且粒度可变的变精度多粒度邻域粗糙集模型,并设计基于矩阵的近似集计算与更新方法：首先提出静态计算近似集的矩阵算法,继而考虑在邻域粒变小时,基于静态计算算法对近似集进行更新,提出一种邻域粒变小时近似集更新的矩阵算法,最后通过UCI公开数据集实验验证了计算与更新算法的有效性。     

一种基于Galois联络的逻辑及其等价形式

将形式化方法引入到Galois联络的研究当中,提出了一种基于Galois联络的逻辑系统LGC,给出了其等价形式并证明了完备性定理.由于Galois联络与粗糙集及概念格有着紧密的联系,故本文的结果对概念格及粗糙集的形式化研究有一定的启示作用.     

基于直觉模糊相似关系下的粗糙集属性约简

描述了直觉模糊相似关系下的粗糙集模型,并在此基础上了定义了正域,依赖度与非依赖度的概念,提出了运用直觉模糊集合理论的粗糙集属性约简算法.最后,用实例证明了该算法的可行性.     

基于完备信息表的IS-概念格构建

本文借鉴在形式背景上构造概念格的方法,利用对象子集的极大描述公式,直接构造完备信息表上的概念格,称为IS-概念格。首先在完备信息表中通过公式和对象子集构造出信息表上的概念,再通过这些概念之间的泛化和特化关系,得到完备信息表上的IS-概念格。为了避免属性冗余,给出了在完备信息表上保持IS-概念格格结构不变的属性约简方法。     

模糊信息系统属性重要性度量

利用包含度工具将粗糙集方法应用在模糊信息系统中,给出了模糊信息系统中属性重要性度量计算方法,通过举例说明了[3]中关于属性重要性度量概念的局限性。     

Study of a universal formal context

Studying a universal formal context, we obtain a number of properties of the context itself, its concepts, and the lattice formed by the set of these concepts. The most significant of these properties is represented by a theorem showing that there exists an embedding of the concept lattice of an arbitrary at most countable universal context into the concept lattice of a universal context under which the image of the embedding is an initial segment of the concept set of a universal formal context with infinite volumes, and the validity of the dual result. It is shown that the theorem also holds in the computable case. This theorem demonstrates the complexity of the structure of a universal formal context.     

Block relations in formal fuzzy concept analysis

One of the main problems in formal concept analysis (especially in fuzzy setting) is to reduce a concept lattice of a formal context to appropriate size to make it graspable and understandable. A natural way to do it is to substitute the formal context by its block relation which is equivalent to factorization of the concept lattice by a complete tolerance. We generalize known results on the correspondence of block relations of formal contexts and complete tolerances on concept lattices to fuzzy setting and we provide an illustrative example of using block relations to reduce the size of a concept lattice.     

基于概念格的决策形式背景属性约简及规则提取

给出了决策形式背景下的属性约简与规则提取方法.为此,针对属性约简中起不同作用的属性,区分了必要属性与不必要属性,给出了各类属性的特征和判别方法;在此基础上得到了决策形式背景下的规则提取与属性约简方法,并通过实例表明了该约简方法的可行性与有效性.     

Incomplete decision contexts: Approximate concept construction,rule acquisition and knowledge reduction

Incomplete decision contexts are a kind of decision formal contexts in which information about the relationship between some objects and attributes is not available or is lost. Knowledge discovery in incomplete decision contexts is of interest because such databases are frequently encountered in the real world. This paper mainly focuses on the issues of approximate concept construction, rule acquisition and knowledge reduction in incomplete decision contexts. We propose a novel method for building the approximate concept lattice of an incomplete context. Then, we present the notion of an approximate decision rule and an approach for extracting non-redundant approximate decision rules from an incomplete decision context. Furthermore, in order to make the rule acquisition easier and the extracted approximate decision rules more compact, a knowledge reduction framework with a reduction procedure for incomplete decision contexts is formulated by constructing a discernibility matrix and its associated Boolean function. Finally, some numerical experiments are conducted to assess the efficiency of the proposed method.     

On computable formal concepts in computable formal contexts

We introduce and study the notions of computable formal context and computable formal concept. We give some examples of computable formal contexts in which the computable formal concepts fail to form a lattice and study the complexity aspects of formal concepts in computable contexts. In particular, we give some sufficient conditions under which the computability or noncomputability of a formal concept could be recognized from its lattice-theoretic properties. We prove the density theorem showing that in a Cantor-like topology every formal concept can be approximated by computable ones. We also show that not all formal concepts have lattice-theoretic approximations as suprema or infima of families of computable formal concepts.     

Axiomatic characterizations of dual concept lattices

Formal concept analysis is an algebraic model based on a Galois connection. It is used for symbolic knowledge exploration from an elementary form of a formal context. This paper mainly presents a general framework for concept lattice in which axiomatic approaches are used. The relationship between concept lattice and dual concept lattice is first studied. Based on set-theoretic operators, generalized concept systems are established. And properties of them are examined. By using axiomatic approaches, a pair of dual concept lattices is characterized by different sets of axioms. The connections between 0-1 binary relations and generalized concept systems are examined. And generalized dual concept systems can be constructed by a pair of dual set-theoretic operators. Axiomatic characterizations of the generalized concept systems guarantee the existence of a binary relation producing a formal context.     

基于对象导出三支概念格的决策背景规则获取

规则获取是当前形式概念分析领域的研究热点.首先给出了基于对象导出三支概念格间的细于关系,定义了基于对象导出三支概念格的三支弱协调性,并研究了其与经典概念格下的二支弱协调性之间的关系.然后,研究了基于对象导出三支概念格的规则获取,并与经典概念格的规则获取进行了比较.最后,定义了对象导出三支概念的弱闭标记,研究了基于弱闭标记的三支弱协调决策形式背景的规则获取,剔除了冗余规则,并且得到一些新的更为精简的三支规则.