Experimental IR meets multilinguality, multimodality, and interaction 9th International Conference of the CLEF Association, CLEF 2018, Avignon, France, September 10-14, 2018 : proceedings - Bellot, Patrice 1972-; Trabelsi, Chiraz; Mothe, Josiane; Murtagh, Fionn 1954-; Nie, Jian-Yun; Soulier, Laure; SanJuan, Eric; Cappellato, Linda; Ferro, Nicola (Lecture notes in computer science, 2018)