1. Department of Mathematics and Computer Science, Avram Iancu University, 1A Ilie Măcelaru, 400380 Cluj-Napoca, Romania
2. Center for Cognitive and Neural Studies (Coneural), 29 Cireşilor, 400487 Cluj-Napoca, Romania
3. Instituto de Física Aplicada, CSIC, Consejo Superior de Investigaciones Científicas, Serrano 144, 28006 Madrid, Spain