18. [C19] On the basis of the discussion of local minima in the error function, carry out an experimental analysis to plot the error surface of the error function of a single neuron for classification by assuming that the inputs are in a two-dimensional space.

#!# 19. [45] Suppose you are given a classification problem in which some of the features of the patterns are missing. Then assume that there is no pattern in the training set for which all features are missing. Analyze a solution based on the idea of expressing the inputs as the data generated by a linear machine which fits the available coordinates.

#!# 1. [18] Consider the definition of f 2 given in Eq. (4.4.85) and the case in which f (x) = 
κ=1 ακ k(x, xκ ) + b with b = 0. How can we redefine f 2?