MultiMedia modeling 27th International Conference, MMM 2021, Prague, Czech Republic, June 22-24, 2021 : proceedings, part II - Lokoč, Jakub; Skopal, Tomáš; Schoeffmann, Klaus; Mezaris, Vasileios ca. 20./21. Jahrhundert; Li, Xirong; Vrochidis, Stefanos; Patras, Ioannis (Information systems and applications, incl. internet/web, and HCI, 2021)