1. COPRIN Team, Sophia Antipolis Research Unit, French National Institute for Computer Science and Control, BP 93, 06902 Sophia Antipolis Cedex, France
2. COPRIN Team, Sophia Antipolis Research Unit, French National Institute for Computer Science and Control, BP 93, 06902 Sophia Antipolis Cedex, France,
3. IMERIR Engineering School of Robotic and Computer Science, BP 2013, 66011 Perpignan Cedex, France