We consider the problem of finding a conformal metric on a compact surface with constant Gaussian curvature and a prescribed conical structure at a given number of points. The problem has a variational structure, and differently from the "regular" case, the Euler-Lagrange functional might be unbounded from below. We will look for critical points of saddle type using a combination of improved geometric inequalities and topological methods.

This is joint work with D. Bartolucci, A. Carlotto, F. De Marchis and D. Ruiz.