1. Department of Computer Science, University of Huddersfield, Huddersfield, U.K.
2. Department of Computer Science, Norwegian University of Science and Technology, Trondheim, Norway
3. School of Informatics, University of Edinburgh, Edinburgh, U.K.
4. Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
5. School of Computer Science and Electronic Engineering, University of Essex, Colchester, U.K.