“…Over the years, scholars have highlighted the importance of exploiting contextual information to provide focused recommendations with the nature of contexts being quite heterogeneous (a summarized description in provided in Table 1), for instance space and time [27], query logs [18,19], statistics on results [23,24] or databases [21], user interests [16], and social data [20]. Given such heterogeneity, other contributions (e.g., [30,31,20]) address the integration of contextual data to provide a common ground (e.g., a global schema [31] or an application programming interface [20]) enabling recommendation from…”