1. Laboratoire d’Informatique de Paris Nord UMR CNRS 7030 Université Paris 13, 99, Avenue J.-B. Clement, 93430 Villetaneuse, France
2. International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), University of Abomey-Calavi, 072 B.P. 50, Cotonou, Republic of Benin
3. Institute for Mathematics, Astrophysics, and Particle Physics, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands