“…In order to address the semantic issues, research works have incorporated knowledge bases such as Wikipedia [29,[55][56][57][58][59][60][61], DBPedia [57,[62][63][64], WordNet [65][66][67], Freebase [68], Linked Open Data (LOD) cloud [49,69,70], and YAGO [71] to semantically represent user models. Semantic enrichment in the user modeling process is motivated by the need to enhance the accuracy of user models [22], increase the breadth of the keyphrases used to represent the users' interests [22,49], gather additional contextual knowledge about the entities and the relationships between them [30,49], infer more transparent and serendipitous user models [56], and bypass the problems of acronyms, synonyms, lexical variants [29], and polysemy, i.e., when a word may have multiple meanings which cannot be distinguished using keyword-based representation [30].…”