Abstract: By integrating variable precision rough fuzzy set and graded rough fuzzy set based on dominance relation, this paper proposes a rough fuzzy set model based on logical and operator of variable precision and grade in ordered information system, and gives the exact definitions of approximations operators and boundary. This model overcomes the shortcoming that the traditional logical and operator rough model cannot solve the problem of fuzzy concept, so the rough set of variable precision and degree has a wider application field. More, some important properties are discussed carefully. Finally, the solving method and significance of the model are shown by the employee case. The new model has extended variable precision rough set model, graded rough set model and classical rough set model, which provides some new theories about knowledge discovery in ordered information system.

Key words: graded rough fuzzy set, logical and operation, ordered information system, rough set theory, variable precision rough fuzzy set

摘要： 在优势关系下将变精度粗糙模糊集与程度粗糙模糊集融合起来，建立了一种基于“逻辑且”的粗糙模糊集模型，并给出了近似区域及边界区域的精确刻画。此模型克服了传统“逻辑且”粗糙模型不能解决模糊对象的问题，使得变精度与程度粗糙集具有更广的应用领域。同时，深入研究了该模型的重要性质。最后，通过员工考核的案例给出了模型具体求解方法和研究意义。序信息系统下变精度与程度的“逻辑且”粗糙模糊集是经典粗糙集理论的延伸和推广，为序信息系统的知识发现提供了新的理论基础。

关键词: 程度粗糙模糊集, 逻辑且, 序信息系统, 粗糙集理论, 变精度粗糙模糊集