There are several criteria in active learning for item selection
and entropy minimization is one of them. In the context of
aspect model, this leads to the following equation for a user
u, where θuz denotes the current user parameters (P(z|u)),
and θuz|m,r denotes user parameters after retraining the usermodel
based on a newly obtained rating r for movie m from
the user i.e. P(z|u, m, r):