“…According to the literature, 53 it can be known that over time, users are able to notice event or people that has a far‐reaching influence on them, so as to form their unique preferences. To extract more comprehensive users' preference information, we increase the vertical depth in the r‐GRU network
54 by exploiting its scalability. In the middle part of Figure 4,
and
represent the vertical depth in the r‐GRU network and the number of time slices
55 (i.e., the horizontal depth in the r‐GRU network), respectively.…”