the system will generate low predicted ratings for that item. This attack was designed to reduce the knowledge required by selecting only a handful of known disliked items. For example, in the movie domain, these may be box office flops that
had been highly promoted prior to their openings.
In Section 25.4, we show that although this attack is not as effective as the more
knowledge-intensive average attack for nuking items in the user-based system, it is
a very effective nuke attack against item-based recommender systems.