• PROFILE LEARNER – This module collects data representative of the user preferences and tries to generalize this data, in order to construct the user profile. Usu-
ally, the generalization strategy is realized through machine learning techniques
[61], which are able to infer a model of user interests starting from items liked or
disliked in the past. For instance, the PROFILE LEARNER of a Web page recommender can implement a relevance feedback method [75] in which the learning
technique combines vectors of positive and negative examples into a prototype
vector representing the user profile. Training examples are Web pages on which
a positive or negative feedback has been provided by the user;