The issue of multiple criteria is discussed in details in Chapter 24. Here we show how to address this issue in group recommender systems.
Table 21.5 resembles the one we had for group recommendation above (Table 21.1), except that now instead of multiple users we have multiple criteria to satisfy. It is possible to apply our group recommendation techniques to this problem. However, there is an important difference between adapting to a group of people and adapting to a group of criteria. When adapting to a group of people, it seems sensible and morally correct to treat everybody equally. Of course, there may be some exceptions, for instance when the group contains adults as well as children, or when it is somebody’s birthday. But in general, equality seems a good choice, and this was used in the group adaptation strategies discussed above. In contrast, when adapting to a group of criteria, there is no particular reason for assuming all criteria are as important. It is even quite likely that not all criteria are equally important to a