传统的粗糙集理论只能对数据库中的离散属性进行处理，所以对存在连续属性的数据库必须进行离散化处理。
The traditional rough set theory can only deal with the discrete attribute in a database, so it is necessary to deal with the consistent attribute when the consistent attributes exist in a database.
粗糙关系数据库模型从本质上来说就是多值信息系统，它继承和扩展了经典的粗糙集理论，但与经典粗糙集理论又有着很大的不同。
Rough relational database model is Multi-valued information system essentially, inheriting and extending classical rough sets theory. But there is much difference between them.
文章提出了一种基于粗糙集理论的文本分类方法。
This paper presents a rough set theory based on the text classification.
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