“…In Zhao, King, and Lyu (2016) three main challenges are identified for these type of systems: physical constraints ( Liu & Xiong, 2013 ), complex relations between data ( Baral and Li, 2017 , Hosseini and Li, 2016 ), and heterogeneous information ( Wang, Li, Liu, & Shao, 2021 ). Others focus on the context integration to improve the quality of recommendations as in Habayeb, Soltanifar, Caglayan, and Bener (2016) and Mourchid, Othman, Kobbane, Sabir, and Koutbi (2016) . While others address specific problems, for instance, in Xia, Li, Li, and Li (2017) neural networks are applied to generate a sequence of recommendations, or in Han and Yamana (2020) the authors seek to diversify the POI recommendations to include new places and those that are not often visited.…”