I have studied Mathematics at Leiden University. My subject was: Singularities of Plane Algebraic Complex Curves and Knot Theory. Since then my interests has grown from analytic combinatorics, set theory to 4-dimensional topology. Right now I am studying 4-dimensional topology (Gompf, Stipsicz, Scopan), but I am also interested in exotic spheres and higher dimensional topology. I am a regular visitor and poster of math.stackexchange