can only take one of the three values: +1, -1, or 0.
the training examples can be divided into three subsets with respect to k: The new loss after adding the update parameter δ to the parameter α k is shown below: The best feature/update pair (k * , δ * ) that minimizes Loss(ᾱ, k, δ) is determined using the following formulas: The update formula in Equation 6 is problematic when either W + k * or W − k * is zero.