1. Department of Computer Science, University of Helsinki, Finland
2. Department of Mathematics and Computer Science, University of Palermo, Palermo, Italy
3. Finnish Centre for Artificial Intelligence FCAI, Department of Computer Science, University of Helsinki, Helsinki, Finland
4. Department of Computer Science, Aalto University, Helsinki, Finland
5. Department of Computer Science, University of Helsinki, Helsinki, Finland
6. IT Center for Science, Espoo, Finland
7. Department of Computer Science, University of Helsinki, Helsinki, Finland and University of Copenhagen, Denmark
8. Finnish Centre for Artificial Intelligence FCAI, Department of Computer Science, Aalto University, Helsinki, Finland and University of Manchester, Manchester, UK