Welschinger invariants of Blow-ups of symplectic 4-manifolds
  Using the degeneration technique, one studies the behavior of Welschinger invariants under the blow-up, and obtains some blow-up formulae of Welschinger invariants. One also analyses the variation of Welschinger invariants when replacing a pair of real points in the real configuration by a pair of conjugated points, and reproves Welschinger's wall crossing formula. 
Yanqiao Ding and Jianxun Hu
math.SG