“…Many researchers [2][3][4]7,8,15,16,18,[20][21][22][23][24][25][26][27][28][33][34][35]41,42,51,52,[54][55][56] have focused on knowledge reduction of dynamic information systems by using incremental learning methods [1,[11][12][13]29,45], which handles the problem of learning new knowledge while maintaining existing knowledge. For instance, Chen et al [2][3][4] constructed approximations of sets under dynamic maintenance environments such as coarsening and refining attribute values and varying attribute sets, which provides an effective approach to attribute reduction of dynamic information systems.…”