Rough set as a classify theory of data mining is a strong mathematic tool dealing with uncertainty and incompleteness, and it can overcome the difficulty in getting knowledge existed before.

粗糙集作为数据挖掘方法的一种，是一种处理不精确或不完整信息的强有力数学工具，并且可以克服以往存在的知识获取瓶颈。

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Yet for all the incompleteness, each book adds considerably to our knowledge of what the Soviets accomplished.

ECONOMIST: History of espionage: Dark secrets | The