Xu and Araki [76] used SVM to build a TV program RS. They used informa-
tion from the Electronic Program Guide (EPG) as features. But in order to reduce
features they removed words with lowest frequencies. Furthermore, and in order to
evaluate different approaches, they used both the Boolean and the Term frequency -
inverse document frequency (TFIDF) weighting schemes for features. In the former,
0 and 1 are used to represent absence or presence of a term on the content. In the
latter, this is turned into the TFIDF numerical value.