1. Institute of Computer Science (ICS), Foundation for Research and Technology - Hellas (FORTH) Heraklion, Greece and Department of Computer Science, Univ. of Crete, Greece
2. Institute of Computer Science (ICS), Foundation for Research and Technology - Hellas (FORTH) Heraklion, Greece and Department of Computer Science, Univ. of Crete, Greece and Institute of Computer Science (ICS), Foundation for Research and Technology - Hellas (FORTH) Heraklion, Greece and Facebook, UK