Institution: | 1. Department of Mathematics, University of Craiova, Craiova, 200585, Romania;2. Institute of Mathematical Statistics and Applied Mathematics of the Romanian Academy (ISMMA), Bucharest, 050711, Romania;3. Inria, SPHINX, Villers-lès-Nancy, F-54600, France;4. Institut Élie Cartan de Lorraine, UMR 7502, Université de Lorraine, CNRS, 54506 Vand?uvre-lès-Nancy Cedex, France |