Lefschetz–Bott Fibrations on Line Bundles Over Symplectic Manifolds

We describe Lefschetz–Bott fibrations on complex line bundles over symplectic manifolds explicitly. As an application, we show that the link of the $A_{k}$-type singularity has more than one strong symplectic filling up to homotopy and blow-up at points when the dimension of the link is greater than or equal to $5$. In the appendix, we show that the total space of a Lefschetz–Bott fibration over the unit disk serves as a strong symplectic filling of a contact manifold compatible with an open book induced by the fibration.

On the Mean Euler Characteristic of Gorenstein Toric Contact Manifolds

We prove that the mean Euler characteristic of a Gorenstein toric contact manifold, that is, a good toric contact manifold with zero 1st Chern class, is equal to half the normalized volume of the corresponding toric diagram and give some applications. A particularly interesting one, obtained using a result of Batyrev and Dais, is the following: twice the mean Euler characteristic of a Gorenstein toric contact manifold is equal to the Euler characteristic of any crepant toric symplectic filling, that is, any toric symplectic filling with zero 1st Chern class.

On symplectic fillings of links of rational surface singularities with reduced fundamental cycle

We prove that every symplectic filling of the link of a rational surface singularity with reduced fundamental cycle admits a rational compactification, possibly after a modification of the filling in a collar neighbourhood of the link.