Abstract
Byline: Jean Bourgain (1), HaIm Brezis (2,3), Petru Mironescu (4) Author Affiliation: (1) grid.78989.37, 0000 0001 2160 7918, School of Mathematics, Institute for Advanced Study, 08540, Princeton, NJ, USA (2) grid.5805.8, 0000 0001 1955 3500, Analyse Numerique, Universite P. et M. Curie, B.C. 187 4 pl. Jussieu, 75252, Paris Cedex 05, France (3) grid.430387.b, 0000 0004 1936 8796, Department of Mathematics, Rutgers University Hill Center, Busch Campus 110 Frelinghuysen Rd, 08854, Piscataway, NJ, USA (4) grid.5842.b, 0000 0001 2171 2558, Departement de Mathematiques, Universite Paris-Sud, 91405, Orsay, France Article History: Registration Date: 25/03/2008 Received Date: 02/06/2001 Online Date: 01/12/2002