共查询到19条相似文献,搜索用时 234 毫秒
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知识约简是粗糙集理论的核心问题之一.通过基于泛系方法论对异同关系和偏序关系的讨论,给出它们之间的联系.然后讨论在粗糙集理论中基于异同关系的数据约简,在此基础上提出约简的本质.将约简应用到了泛序系统中. 相似文献
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分析了变精度粗糙集模型约简异常出现的原因,结合变精度粗糙集模型特征,将特定β值上的约简扩展为区间约简,并从分类质量、β相对正域和决策类三个层次分别对约简进行描述,研究了它们与约简异常之间的关系。区间约简评价因子的提出,对评价及选择区间约简有重要指导意义。 相似文献
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基于概念格的形式背景的知识约简 总被引:1,自引:0,他引:1
概念格作为一种数学方法在数据挖掘和知识处理中有重要意义.本文基于概念格提出了关于形式背景的知识约简理论,并借助于粗糙集理论中关于信息系统知识约简的思想,给出了概念格中形式背景约简的判定定理和相应的可辨识属性矩阵,从而为概念格中形式背景知识约简提供了一种有效方法. 相似文献
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随着计算机网络的发展,多个形式背景分布存储在不同的网络节点,研究合成背景的属性约简就显得十分重要。提出了一种多背景纵向合成的面向对象概念格的属性约简方法,给出了面向对象概念格的属性近似算子真子集的定义,并给出了各子形式背景和合成形式背景的属性特征间的关系,在此基础上,给出了合成形式背景的属性近似算子真子集、子形式背景的属性近似算子真子集和属性等价类间的关系,并利用它们间的关系给出了合成背景的各种属性判别的充要条件,进而给出了合成背景属性约简的构造算法。 相似文献
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形式背景的属性约简是形式概念分析的重要研究方向。研究者针对形式背景提出了多种属性约简标准并建立了属性约简方法。文中研究了形式背景基于对象导出三支概念格的约简问题,通过刻画对象之间的区分属性提出了一种新的粒约简计算方法,该方法无需构造基于对象导出的三支概念格;同时,证明了基于三支概念格的形式背景粒约简与基于粗糙集理论的分类约简等价。 相似文献
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基于粗糙概念格的属性约简及规则获取 总被引:2,自引:0,他引:2
基于粗糙集和概念格理论进行结合,给出了决策背景下的多属性约简与规则提取方法。为此,针对决策背景的辨识矩阵和辨识函数给出了决策背景属性约简的具体属性约简方法;在此基础上得到了决策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. 相似文献
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不完备有序信息系统粗糙集模型是经典粗糙集的扩展,利用优势关系代替等价关系能很好地处理含未知属性值和带有偏好关系的数据。研究了不完备序信息系统的证据特征,给出了不完备序上、下近似算子,并证明了二者分别与证据理论中的似然函数、信任函数相对应。进而提出了不完备序信息系统的[R]约简、信任约简以及似然约简的概念,探讨了它们之间的一致性,证明了[R]约简与信任约简是等价的,均是保持信任函数和的最小属性集合,得出了似然约简协调集必为[R]约简协调集的结论。 相似文献
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In formal concept analysis ,concept lattice as the fundamental data structure can be construct-ed front a formal context. Howevt, r,it is required that the relation between object and feature in the for-real context should be certain, For uncertain relation,this paper uses the thoughts of upper and lowerapproximation in rough set theory to deal with it ,and gives out the corresponding definitions of missing-value context and rough formal concept, Based on them, this paper employs rough concept lattice,formed by rough formal concepts and partial order relation on them,as the basic data structure for con-cept analysis and knowledge acquisition. Then a theroem is presented to describe the method of extract-ing rules from constructed rough formal concept lattice,and the semantic interpretation of discoveredrules is explained. 相似文献
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形式概念分析与粗糙集理论是两种有效的知识发现工具,已在各个领域获得成功应用。本文给出了一种将形式背景转化为集值信息系统的方法,证明了形式背景分析中的对象粒协调集与由该形式背景导出的集值信息系统的协调集是等价的,并且分析了形式背景中三种不同类型的对象粒属性特征。最后给出了形式背景中属性粒的概念及相关结论。 相似文献
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This paper investigates approaches to attribute reduction in concept lattices induced by axialities. Based on an axiality, a type of covariant Galois connection between power sets, or equivalently a binary relation between the ground sets, the lattice of all concepts associated with a formal context is studied. Some judgment theorems for attribute reduction in such a lattice are proposed and proved. Extended from the idea of knowledge reduction in rough set theory, a Boolean approach to calculating all reducts of a context is formulated via the use of discernibility function. Finally, all attributes are classified into three types by their significance in constructing the concept lattice. The characteristics of these types of attributes are also analyzed. 相似文献
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《Computers & Mathematics with Applications》2007,53(9):1390-1410
Rough set theory and formal concept analysis are two complementary mathematical tools for data analysis. In this paper, we study the reduction of the concept lattices based on rough set theory and propose two kinds of reduction methods for the above concept lattices. First, we present the sufficient and necessary conditions for justifying whether an attribute and an object are dispensable or indispensable in the above concept lattices. Based on the above justifying conditions, we propose a kind of multi-step attribute reduction method and object reduction method for the concept lattices, respectively. Then, on the basis of the defined discernibility functions of the concept lattices, we propose a kind of single-step reduction method for the concept lattices. Additionally, the relations between the attribute reduction of the concept lattices in FCA and the attribute reduction of the information system in rough set theory are discussed in detail. At last, we apply the above multi-step attribute reduction method for the concept lattices based on rough set theory to the reduction of the redundant premises of the multiple rules used in the job shop scheduling problem. The numerical computational results show that the reduction method for the concept lattices is effective in the reduction of the multiple rules. 相似文献