第四章作者讨论了将变精度方法引入到模糊粗糙集，给出了一个变精度模糊粗糙集模型。

The forth chapter is to try to introduce the variable precision methods into the fuzzy information processing.

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另一方面提出了在一定错分率存在的条件下的模糊集合间的相对错分率，之后结合这两个理论给出了基于模糊邻域算子的模糊变精度粗糙集模型。

Then, the mistake classification rate between two fuzzy sets is defined. Later, fuzzy variable precision rough set model is proposed based on the two definitions.

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