Topological obstructions for rational cuspidal curves in Hirzebruch   surfaces
  We study rational cuspidal curves in Hirzebruch surfaces. We provide two obstructions for the existence of rational cuspidal curves in Hirzebruch surfaces with prescribed types of singular points. The first result comes from Heegaard--Floer theory and is a generalization of a result by Livingston and the first author. The second criterion is obtained by comparing the spectrum of a suitably defined link at infinity of a curve with spectra of its singular points. 
Maciej Borodzik, Torgunn Karoline Moe
math.AG math.GT