Machine Learning Algorithms - Second Edition

Model-based collaborative filtering

This is currently one of the most advanced approaches and is an extension of what was already seen in the previous section. The starting point is always a rating-based user-item matrix:

However, in this case, we assume the presence of latent factors for both the users and the items. In other words, we define a generic user as follows:

A generic item is defined as follows:

We don't know the value of each vector ...