In (Hastie 98), the authors proposed to minimize the Kullback-Leibler (KL) distance between the r ij and u ij where r ij and u ij are the probabilities of a pairwise a i and a j in the estimated model and in our model, respectively, and n ij is the number of training data in which their classes are a i or a j .
to find the minimizer of equation 6, they first calculate letting ∆l(p) = 0, they proposed to find a point satisfying where i = 1, 2, ...k and p i > 0.