关键词: 粗糙集, 上下近似, 矩阵刻画, 关系矩阵方程

Abstract: The matrix description and application of upper and lower approximation of rough set have studied in this paper. The new matrix descriptions of upper and lower approximation under equivalence relations, general binary and covering rough set based on the neighborhood are given. As an application, the inverse problems of upper and lower approximation have solved by using relationship matrix equation, that is, the method to solve[X]is given if the relationship matrix[MR]and the upper approximation[R(X)]（or lower approximation[R(X)]） have known.

Key words: rough set, upper and lower approximation, matrix description, relationship matrix equation