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模糊聚类动态图的性质 被引量:2
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作者 许伯济 《现代地质》 CAS CSCD 1991年第2期215-221,共7页
模糊聚类分析在地学中有广泛应用。其核心问题之一是确定相似系数。目前有14种以上的定义,且多含有参数。为免除应用者选择之苦,本文证明对某几种相似系数定义中的不同参数值都代表相同的分类结构,只要适当选择一个参数值就够了。核心... 模糊聚类分析在地学中有广泛应用。其核心问题之一是确定相似系数。目前有14种以上的定义,且多含有参数。为免除应用者选择之苦,本文证明对某几种相似系数定义中的不同参数值都代表相同的分类结构,只要适当选择一个参数值就够了。核心问题之二是作出聚类动态图。本文引入等价模糊矩阵的脊形变换得到脊形矩阵,已证明n阶脊形矩阵至多含有n个互异元素(包括主对角线元素1),它们分布在1级对角线上。取这些数值作为人阀值就能作出聚类动态图。对于众多的分类集合U,脊形变换能使U的元素重新排列,使任一等价类的元素都相邻排列,便于计算机自动输出聚类动态图。 展开更多
关键词 聚类分析 脊形矩阵 动态图
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Practical Secret Sharing Scheme Realizing Generalized Adversary Structure 被引量:2
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作者 Yuan-BoGuo Jian-FengMa 《Journal of Computer Science & Technology》 SCIE EI CSCD 2004年第4期564-569,共6页
Most existing secret sharing schemes are constructed to realize generalaccess structure, which is defined in terms of authorized groups of participants, and is unable tobe applied directly to the design of intrusion t... Most existing secret sharing schemes are constructed to realize generalaccess structure, which is defined in terms of authorized groups of participants, and is unable tobe applied directly to the design of intrusion tolerant system, which often concerns corruptiblegroups of participants instead of authorized ones. Instead, the generalized adversary structure,which specifies the corruptible subsets of participants, can be determined directly by exploit ofthe system setting and the attributes of all participants. In this paper an efficient secret sharingscheme realizing generalized adversary structure is proposed, and it is proved that the schemesatisfies both properties of the secret sharing scheme, i.e., the reconstruction property and theperfect property. The main features of this scheme are that it performs modular additions andsubtractions only, and each share appears in multiple share sets and is thus replicated. The formeris an advantage in terms of computational complexity, and the latter is an advantage when recoveryof some corrupted participants is necessary. So our scheme can achieve lower computation cost andhigher availability. Some reduction on the scheme is also done finally, based on an equivalencerelation defined over adversary structure. Analysis shows that reduced scheme still preserves theproperties of the original one. 展开更多
关键词 secret sharing generalized adversary structure write structure equivalenceclass REDUCTION
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