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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. 相似文献
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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. 相似文献
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《数学的实践与认识》2017,(24)
粗糙集的拓扑研究具有意义,其中的近似拓扑具有对经典拓扑的双向逼近性.研究基于近似拓扑的近似闭包.定义近似开集确立近似拓扑,建立近似闭集.基于近似闭集,定义近似闭包获得基本性质,分析近似闭包与闭包、闭包近似集、近似集闭包的包含序关系.近似闭包深化了近似拓扑,实现了对经典闭包的逼近与扩张. 相似文献
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杨晓平 《数学的实践与认识》2009,39(20)
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. 相似文献
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Covering-based rough sets,as a technique of granular computing,can be a useful tool for dealing with inexact,uncertain or vague knowledge in information systems.Matroids generalize linear independence in vector spaces,graph theory and provide well established platforms for greedy algorithm design.In this paper,we construct three types of matroidal structures of covering-based rough sets.Moreover,through these three types of matroids,we study the relationships among these matroids induced by six types of covering-based upper approximation operators.First,we construct three families of sets by indiscernible neighborhoods,neighborhoods and close friends,respectively.Moreover,we prove that they satisfy independent set axioms of matroids.In this way,three types of matroidal structures of covering-based rough sets are constructed.Secondly,we study some characteristics of the three types of matroid,such as dependent sets,circuits,rank function and closure.Finally,by comparing independent sets,we study relationships among these matroids induced by six types of covering-based upper approximation operators. 相似文献
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In this paper, we consider the electromagnetic scattering from periodic chiral structures. The structure is periodic in one direction and invariant in another direction. The electromagnetic fields in the chiral medium are governed by the Maxwell equations together with the Drude-Born-Fedorov equations. We simplify the problem to a two-dimensional scattering problem and we show that for all but possibly a discrete set of wave numbers, there is a unique quasi-periodic weak solution to the diffraction problem. The diffraction problem can be solved by finite element method. We also establish uniform error estimates for the finite element method and the error estimates when the truncation of the nonlocal transparent boundary operators takes place. 相似文献
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拟阵是图论与代数的结合,而拓扑学是一门重要的数学基础学科.利用拟阵理论研究拓扑空间,从而将两者进行融合,通过拟阵的闭包算子定义拟阵拓扑空间,进一步利用拟阵闭包算子与拓扑闭包算子之间的关系,讨论拟阵拓扑空间的分离性. 相似文献
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In this note, the author discusses the problem of best simultaneous approximation by function pairs. The existence and characterization theorems of the best simultaneous approximation in L1 and L∞ norms are obtained respectively, and some rezults of [ 1 ] are the special case of the theorems of the paper. 相似文献
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设 p是一个素数 ,n是任意正整数 ,函数α(n ,p)表示 p在n !标准分解式中的指数 ,本文给出了函数α(n ,p)的均值 ∑n相似文献
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引入了一个广义凸函数一高阶强Pre-invex函数,它是Guneer-Bhatia介绍的高阶强凸函数的一种推广.在此基础上,讨论并证明了高阶强Pre-invex函数的一些等价刻画,这些结论是Guneer-Bhatia给出结论的推广,扩大了凸函数的应用范围. 相似文献
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Mathematical Notes - We consider a characteristic simultaneously reflecting certain properties of Riemann integrable functions f on the closed interval [0, 1] and properties of some sequence X =... 相似文献