1. E.T.S.I. Informática, Dpto. Matemática Aplicada I , Universidad de Sevilla Avda . Reina Mercedes s/n , Sevilla , Spain
2. CMCC , Universidade Federal do ABC , Santo André , Brazil Av. dos Estados, 5001 – Bangú, Santo André – SP, 09210-580
3. Laboratory of Modern Algebra and Applications , St. Petersburg State University and St. Petersburg Department of Steklov Mathematical Institute , St. Petersburg , Russia
4. Deptartment of Mathematical Sciences , United Arab Emirates University , , Al Ain , United Arab Emirates