多粒度空间中的层次结构
Hierarchical Structures on Multigranulation Spaces
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摘要: 近年来,很多学者提出了若干种不同形式的层次结构用以描述不同单粒度粒空间之间的粗细关系.但值得注意的是,多粒度在粒计算理论中是一个非常重要的概念,因而对不同多粒度空间之间的粗细关系进行分析就显得尤为重要.为了解决这个问题,考虑了两种不同形式的多粒度空间,即划分和覆盖多粒度空间,在这两种多粒度空间中,分别提出了三种不同形式的层次结构,不仅对这些层次结构的性质进行了讨论,而且对这三种层次结构与多粒度粗糙集之间的关系进行了深入讨论,得出的结论是,第一种层次结构与乐观多粒度粗糙集的单调变化存在着对应关系,第二种层次结构与悲观多粒度粗糙集的单调变化存在着对应关系,而第三种层次结构则同时与乐观和悲观多粒度粗糙集的单调变化存在着对应关系.Abstract: Though many hierarchical structures have been proposed to analyze the finer or coarser relationships between two granulation spaces, these structures can only be used to compare the single granulation spaces. However, it should be noticed that the concept of multigranulation plays a fundamental role in the development of granular computing. Therefore, the comparison between two multigranulation spaces has become a necessity. To solve such problem, two types of the multigranulation spaces are considered: one is the partition-based multigranulation space, the other is the covering-based multigranulation space. Three different hierarchical structures are then proposed on such two multigranulation spaces, respectively. Not only the properties about these hierarchical structures are discussed, but also the relationships between these hierarchical structures and the multigranulation rough sets are deeply investigated. It is shown that the first hierarchical structure is consistent with the monotonic varieties of optimistic multigranulation rough set, and the second hierarchical structure is consistent to the monotonic varieties of pessimistic multigranulation rough set, the third hierarchical structure is consistent to the monotonic varieties of both optimistic and pessimistic multigranulation rough sets.
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