Best remainder norms in Sobolev-Hardy inequalities Andrea CianchiAdele Ferone 46E3546E30Hardy inequalitySobolev spacesLorentz spacesremainder termssymmetrizationrearrangement invariant spaces We exhibit the optimal norm for a remainder term in the sharp Sobolev inequality involving a Lorentz norm, and in the equivalent classical Hardy inequality. Limiting cases of the relevant inequalities are also considered. Indiana University Mathematics Journal 2009 text pdf 10.1512/iumj.2009.58.3561 10.1512/iumj.2009.58.3561 en Indiana Univ. Math. J. 58 (2009) 1051 - 1096 state-of-the-art mathematics http://iumj.org/access/