Dr Costas Christidis holds a Diploma (2007) from the School of Electrical and Computer Engineering of the National Technical University of Athens (Greece). His Diploma Thesis was in the area of Web Services and Mobile Communications and his PhD thesis on “Probabilistic Topic Models in Recommender Systems” (2013). He has also worked as an Administrator in the Computer Center of the School of Electrical and Computer Engineering. He was a senior researcher at the Information Management Unit.