共查询到15条相似文献,搜索用时 390 毫秒
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顾艳红 《纯粹数学与应用数学》2011,27(2):236-239
利用Lagrange定理和正多边形对称群的性质,首先对正多边形对称群的子群的性质进行了研究,其次讨论了正多边形对称群的子群的结构,由此完全确定了正多边形对称群的子群,最后应用所得结论求出了正六边形对称群的所有子群. 相似文献
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对粗糙集上代数结构进行了研究,引入了粗糙除环、粗糙域和粗糙整环等概念.利用粗糙集理论方法和经典代数中的处理手段,讨论了粗糙除环和它们的结构特征,得到了它们的一些良好的性质. 相似文献
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覆盖粗糙模糊集的不确定性度量 总被引:2,自引:0,他引:2
在覆盖粗糙模糊集模型下,将粗糙集理论中的粗糙度和粗糙熵的概念引入到此模型中,用来度量模糊集的不确定的程度,并讨论了这些度量的一些性质. 相似文献
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子群陪集与群同态基本定理的一种几何模型 总被引:1,自引:0,他引:1
本文研究了子群、群同态基本定理的几何意义.利用二、三维几何空间图形,得到了子群陪集、不变子群对群的分类、商群、同态满射和群同态基本定理的几何模型,为认识上述抽象的代数内容提供了直观的几何解释,同时也给出了其几何表示. 相似文献
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Zhang Qinhai 《东北数学》1998,(1)
The concept of an abnormal subgroup of a group G is, in a sense, opposite of thatof a normal subgroup of G. In [J. Algebra, 28(1974), 15-19) Fattahi studied those finitegroups in which each subgroup is either normal or abnormal and characterized all suchgroups. In this paper, as a generalization of Fattahi's result, we study more general groups,i. e., groups with only s-quasinormal and abnormal subgroups and characterize all suchgroups. Morever, some interesting conclusions are also obtained. 相似文献
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Monotonic Variable Consistency Rough Set Approaches 总被引:2,自引:0,他引:2
Jerzy Baszczyski Salvatore Greco Roman Sowiski Marcin Szel
g 《International Journal of Approximate Reasoning》2009,50(7):979
We consider probabilistic rough set approaches based on different versions of the definition of rough approximation of a set. In these versions, consistency measures are used to control assignment of objects to lower and upper approximations. Inspired by some basic properties of rough sets, we find it reasonable to require from these measures several properties of monotonicity. We consider three types of monotonicity properties: monotonicity with respect to the set of attributes, monotonicity with respect to the set of objects, and monotonicity with respect to the dominance relation. We show that consistency measures used so far in the definition of rough approximation lack some of these monotonicity properties. This observation led us to propose new measures within two kinds of rough set approaches: Variable Consistency Indiscernibility-based Rough Set Approaches (VC-IRSA) and Variable Consistency Dominance-based Rough Set Approaches (VC-DRSA). We investigate properties of these approaches and compare them to previously proposed Variable Precision Rough Set (VPRS) model, Rough Bayesian (RB) model, and previous versions of VC-DRSA. 相似文献
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研究粗糙模糊集、模糊粗糙集、广义粗糙模糊集和广义模糊粗糙集的截集性质,并且还研究了基于逻辑算子的广义模糊粗糙集的基本性质。 相似文献