TOPOLOGY SEMINAR

10/8/2009

Andras Stipsicz
Renyi Institute

Rational homology disks and symplectic topology

Surface singularities admitting a smoothing with the homology of the 4--disk (a so-called rational homology disk, QHD) play central role in the construction of exotic 4-manifolds through the 'rational blow down process'. Applying various forms of gauge theory we derive obstructions for a singularity to admit such smoothings. Using symplectic topology we classify all starshaped resolution graphs with QHD smoothings.