Isoperimetry and Symmetrization for Sobolev spaces on metric spaces
  Using isoperimetry we obtain new symmetrization inequalities that allow us to provide a unified framework to study Sobolev inequalities in metric spaces. The applications include concentration inequalities, as well as metric versions of the P\'{o}% lya-Szeg\"{o} and Faber-Krahn principles. 
Joaquim Martin, Mario Milman