A note on symplectic rational blow--downs
  Due to a significant error in the main result (pointed out by J. Wahl), the paper has been withdrawn by the authors. A corrected and expanded version is 'Rational blow-downs and smoothings of surface singularities' by A. Stipsicz, Z. Szabo and J. Wahl. 
Andras I. Stipsicz and Zoltan Szabo