Abstract: Variable precision rough set model and grade rough set model are two important expanding rough set models. Precision and grade relate to the relative and absolute quantitative information in approximate space respectively. To integrate relative quantitative information and absolute quantitative information and make rough set possess the stronger data processing ability and wider application fields, this paper proposes the model of rough set based on logical disjunct operation of variable precision and grade in ordered information system. This paper also discusses the basic structure and accurate description of a rough set respectively, and investigates some important properties of the model carefully. Furthermore, this paper analyzes a specific case study about the student achievement, discusses the significance of study on logical disjunct operation of variable precision and grade rough set models, and provides more abundant theoretical basis for knowledge discovery in ordered information systems.

Key words: variable precision rough set, grade rough set, ordered information system, logical disjunct operation

摘要： 变精度粗糙集模型和程度粗糙集模型是两类重要的粗糙集扩张模型，其中精度反映了近似空间的相对量化信息，而程度则刻画了近似空间的绝对量化信息。为了融合相对量化信息和绝对量化信息，使粗糙集具有更强的数据处理能力与更广的适用领域，提出了序信息系统下的变精度与程度“逻辑或”粗糙集的概念，得到其粗糙集区域的基本结构和精确描述，深入讨论了其重要性质。结合学生成绩这一具体案例的求解分析，进一步阐述了对变精度与程度的“逻辑或”粗糙集进行研究的意义，为序信息系统的知识发现提供了更丰富的理论基础。

关键词: 变精度粗糙集, 程度粗糙集, 序信息系统, 逻辑或