For recommendation, there are extensive efforts on post-level recommendation (Chen et al., 2012; Yan et al., 2012) and conversation-level (Chen et al., 2011; Zeng et al., 2018, 2019b).
with them which assume static user interests, we capture how user interests change over time and take advantage of the recent advancement of dynamic product recommendation (Wu et al., 2017;Beutel et al., 2018).