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  • Boz Handy-Bosma thinks this is interesting:

To solve this recommendation problem, a recommender system generally uses three types of data—data about the users (U_data), data about the items such as goods, services or information (I_data), and data about the relevance (such as rating, evaluation, purchase, or interest) relation between the users and the items (R_data):

  • U_data contains a set of all users and some optional additional information about all users.
  • I_data contains a set of all items and some optional additional information about all items.