  Current approaches for points-of-interest (POI) recommendation learn the
preferences of a user via the standard spatial features such as the POI
coordinates, the social network, etc. These models ignore a crucial aspect of
spatial mobility -- every user carries their smartphones wherever they go. In
addition, with growing privacy concerns, users refrain from sharing their exact
geographical coordinates and their social media activity. In this paper, we
present REVAMP, a sequential POI recommendation approach that utilizes the user
activity on smartphone applications (or apps) to identify their mobility
preferences. This work aligns with the recent psychological studies of online
urban users, which show that their spatial mobility behavior is largely
influenced by the activity of their smartphone apps. In addition, our proposal
of coarse-grained smartphone data refers to data logs collected in a
privacy-conscious manner, i.e., consisting only of (a) category of the
smartphone app and (b) category of check-in location. Thus, REVAMP is not privy
to precise geo-coordinates, social networks, or the specific application being
accessed. Buoyed by the efficacy of self-attention models, we learn the POI
preferences of a user using two forms of positional encodings -- absolute and
relative -- with each extracted from the inter-check-in dynamics in the
check-in sequence of a user. Extensive experiments across two large-scale
datasets from China show the predictive prowess of REVAMP and its ability to
predict app- and POI categories.
