【摘要】 信息系统和形式背景是数据库中对象与属性之间关系的两种不同表现形式,是数据挖掘与知识发现的重要内容.本文基于粗糙集理论对两者进行了研究,指出了每个信息系统均存在一个与之对应的形式背景,通过这个形式背景可以确定信息系统的分类知识及由此划分形成的集代数.最后,文中给出了形式背景中所有概念外延组成的集合与信息系统中由划分形成的集代数相等的充分必要条件。由此,利用形式背景中的外延即可获得相应的粗近似。更多还原

【Abstract】 Information systems and formal contexts are two kinds of representations describing the relationship between objects and attributes in databases. They are the important contents of data mining and knowledge discovery. Based on the rough set theory, this paper investigates the relation of information systems and formal contexts, and then points out that each information system exists a corresponding formal context. By means of the formal context, we may determine the classified knowledge of information system and the set algebra generated by the classification. Finally, the paper presents a necessary and sufficient condition for the set of all extents of the formal context being equal to the set algebra of the information system. The rough approximation is thus obtained by using the extents of the formal context.更多还原