Predicting relative preferences. An alternative way to define the multi-criteria
recommendation problem could be formulated as predicting the relative preferences
of users, as opposed to the absolute rating values. There has been some work on
constructing the correct relative order of items using ordering-based techniques. For
example, Freund et al. [25] developed the RankBoost algorithm based on the wellknown AdaBoost method and, in multi-criteria settings, such algorithms could be
adopted to aggregate different relative orders obtained from different rating criteria
for a particular user. In particular, this is an approach taken by the DIVA system
[59, 60].