关键词: 粗糙集, 正区域, 不可分辨关系

Abstract: The computing of position region is very important in the application of rough set.Based on an in-depth study of rough set theory，mainly focusing on indiscernibility relation，a equivalent method for computing positive region is proposed.Then，the detailed descriptions of the algorithm for computing of positive region is analyzed based on universe decrement.The algorithm classifies samples in universe step by step and determines whether those samples belong to position region and deletes the samples from universe to reduce computational complexity.Finally，in order to test the efficiency of the algorithm，some experiments are made.And the theoretical analysis and experimental results show that this new method is much more efficient and useful in computing.

Key words: rough set, positive region, indiscernibility relation