where i denotes the ith dimension; ubi and lbi denote the upper and lower boundaries of values in the ith dimension, respectively; nopi denotes the total number of possible separation boundaries in the ith dimension, which if not specifically stated otherwise, is assigned to the total number of different values in the ith dimension where corresponding values in the decision attribute are changed across; and M denotes the user specified minimum number of separation boundaries in every dimension, which has a default value of 10.