3 DNF expressions were specifically chosen because of their simplicity as well as their similarity to text data whose classification accuracy we are ultimately interested in improving.
like in the case of text-classification, DNF concepts of interest are, generally, represented by much fewer examples than there are counter-examples of these concepts, especially when 1) the concept at hand is fairly specific; 2) the number of disjuncts and literals per disjunct grows larger; and 3) the values assumed by the literals are drawn from a large alphabet.