My main research interest is convex geometry, which includes classical results like Helly's theorem, or Radon's theorem, then lattice points and random points related to convex bodies. I'm also working in geometry of numbers and its applications in integer programming. A further example is how well a convex body in d-dimensional space can be approximated by polytopes having n vertices. As an application in computer science I showed that every effective or fast algorithm that estimates the volume of convex bodies necessarily makes a huge error. This is the content of my paper, Computing the volume is difficult, a joint work with Z Furedi, that appeared in Discrete and Computational Geometry, 1988.