1. Institute for Interdisciplinary Studies on Artificial Intelligence (IRIDIA), Université Libre de Bruxelles, B1050 Brussels, Belgium; Centre for the Advanced Study of Collective Behaviour, Universität Konstanz, 78464 Konstanz, Germany; and Department of Collective Behavior, Max Planck Institute of Animal Behavior, 78464 Konstanz, Germany
2. Faculty of Computer Science and Namur Institute for Complex Systems, naXys Université de Namur, Rue Grandgagnage 21, B5000 Namur, Belgium
3. Department of Mathematics and Namur Institute for Complex Systems, naXys Université de Namur, Rue Grafé 2, B5000 Namur, Belgium