Raafat Talhouk
Professor at the
École Supérieure d'Ingénieurs Léonard de Vinci-ESILV, Paris-La Défense.
and
Lebanese University,
Faculty of Science I,
department of mathematics,
Hadat-Lebanon.
Email: raafat.talhouk AT devinci.fr ; rtalhouk AT ul.edu.lb or talhoukr AT gmail.com